object_constraint.c

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/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): Joshua Leung, Blender Foundation
 *
 * ***** END GPL LICENSE BLOCK *****
 */

#include <stdio.h>
#include <string.h>

#include "MEM_guardedalloc.h"

#include "BLI_blenlib.h"
#include "BLI_math.h"
#include "BLI_dynstr.h"
#include "BLI_utildefines.h"

#include "DNA_constraint_types.h"
#include "DNA_curve_types.h"
#include "DNA_scene_types.h"
#include "DNA_text_types.h"
#include "DNA_object_types.h"

#include "BKE_action.h"
#include "BKE_armature.h"
#include "BKE_constraint.h"
#include "BKE_context.h"
#include "BKE_depsgraph.h"
#include "BKE_global.h"
#include "BKE_main.h"
#include "BKE_object.h"
#include "BKE_report.h"
#include "BKE_tracking.h"
#include "BIK_api.h"

#ifdef WITH_PYTHON
#include "BPY_extern.h"
#endif

#include "WM_api.h"
#include "WM_types.h"

#include "RNA_access.h"
#include "RNA_define.h"
#include "RNA_enum_types.h"

#include "ED_object.h"
#include "ED_armature.h"
#include "ED_screen.h"

#include "UI_interface.h"
#include "UI_resources.h"

#include "object_intern.h"

/* -------------- Get Active Constraint Data ---------------------- */

/* if object in posemode, active bone constraints, else object constraints */
ListBase *get_active_constraints (Object *ob)
{
    if (ob == NULL)
        return NULL;
    
    if (ob->mode & OB_MODE_POSE) {
        bPoseChannel *pchan;
        
        pchan = get_active_posechannel(ob);
        if (pchan)
            return &pchan->constraints;
    }
    else 
        return &ob->constraints;
    
    return NULL;
}

/* Find the list that a given constraint belongs to, and/or also get the posechannel this is from (if applicable) */
ListBase *get_constraint_lb (Object *ob, bConstraint *con, bPoseChannel **pchan_r)
{
    if (pchan_r)
        *pchan_r= NULL;
    
    if (ELEM(NULL, ob, con))
        return NULL;
    
    /* try object constraints first */
    if ((BLI_findindex(&ob->constraints, con) != -1)) {
        return &ob->constraints;
    }
    
    /* if armature, try pose bones too */
    if (ob->pose) {
        bPoseChannel *pchan;
        
        /* try each bone in order 
         * NOTE: it's not possible to directly look up the active bone yet, so this will have to do
         */
        for (pchan= ob->pose->chanbase.first; pchan; pchan= pchan->next) {
            if ((BLI_findindex(&pchan->constraints, con) != -1)) {
                
                if (pchan_r)
                    *pchan_r= pchan;
                
                return &pchan->constraints;
            }
        }
    }
    
    /* done */
    return NULL;
}

/* single constraint */
bConstraint *get_active_constraint (Object *ob)
{
    return constraints_get_active(get_active_constraints(ob));
}

/* -------------- Constraint Management (Add New, Remove, Rename) -------------------- */
/* ------------- PyConstraints ------------------ */

/* this callback sets the text-file to be used for selected menu item */
static void validate_pyconstraint_cb (void *arg1, void *arg2)
{
    bPythonConstraint *data = arg1;
    Text *text= NULL;
    int index = *((int *)arg2);
    int i;
    
    /* exception for no script */
    if (index) {
        /* innovative use of a for...loop to search */
        for (text=G.main->text.first, i=1; text && index!=i; i++, text=text->id.next);
    }
    data->text = text;
}

#ifdef WITH_PYTHON
/* this returns a string for the list of usable pyconstraint script names */
static char *buildmenu_pyconstraints (Text *con_text, int *pyconindex)
{
    DynStr *pupds= BLI_dynstr_new();
    Text *text;
    char *str;
    char buf[64];
    int i;
    
    /* add title first */
    sprintf(buf, "Scripts: %%t|[None]%%x0|");
    BLI_dynstr_append(pupds, buf);
    
    /* init active-index first */
    if (con_text == NULL)
        *pyconindex= 0;
    
    /* loop through markers, adding them */
    for (text=G.main->text.first, i=1; text; i++, text=text->id.next) {
        /* this is important to ensure that right script is shown as active */
        if (text == con_text) *pyconindex = i;
        
        /* only include valid pyconstraint scripts */
        if (BPY_is_pyconstraint(text)) {
            BLI_dynstr_append(pupds, text->id.name+2);
            
            sprintf(buf, "%%x%d", i);
            BLI_dynstr_append(pupds, buf);
            
            if (text->id.next)
                BLI_dynstr_append(pupds, "|");
        }
    }
    
    /* convert to normal MEM_malloc'd string */
    str= BLI_dynstr_get_cstring(pupds);
    BLI_dynstr_free(pupds);
    
    return str;
}
#endif /* WITH_PYTHON */

#if 0 // UNUSED, until pyconstraints are added back.
/* this callback gets called when the 'refresh' button of a pyconstraint gets pressed */
static void update_pyconstraint_cb (void *arg1, void *arg2)
{
#ifndef WITH_PYTHON
    (void)arg1; /* unused */
    (void)arg2; /* unused */
#else
    Object *owner= (Object *)arg1;
    bConstraint *con= (bConstraint *)arg2;
    if (owner && con)
        BPY_pyconstraint_update(owner, con);
#endif
}
#endif // UNUSED

/* helper function for add_constriant - sets the last target for the active constraint */
static void set_constraint_nth_target (bConstraint *con, Object *target, const char subtarget[], int index)
{
    bConstraintTypeInfo *cti= constraint_get_typeinfo(con);
    ListBase targets = {NULL, NULL};
    bConstraintTarget *ct;
    int num_targets, i;
    
    if (cti && cti->get_constraint_targets) {
        cti->get_constraint_targets(con, &targets);
        num_targets= BLI_countlist(&targets);
        
        if (index < 0) {
            if (abs(index) < num_targets)
                index= num_targets - abs(index);
            else
                index= num_targets - 1;
        }
        else if (index >= num_targets) {
            index= num_targets - 1;
        }
        
        for (ct=targets.first, i=0; ct; ct= ct->next, i++) {
            if (i == index) {
                ct->tar= target;
                BLI_strncpy(ct->subtarget, subtarget, sizeof(ct->subtarget));
                break;
            }
        }
        
        if (cti->flush_constraint_targets)
            cti->flush_constraint_targets(con, &targets, 0);
    }
}

/* ------------- Constraint Sanity Testing ------------------- */

/* checks validity of object pointers, and NULLs,
 * if Bone doesnt exist it sets the CONSTRAINT_DISABLE flag.
 */
static void test_constraints (Object *owner, bPoseChannel *pchan)
{
    bConstraint *curcon;
    ListBase *conlist= NULL;
    int type;
    
    if (owner==NULL) return;
    
    /* Check parents */
    if (pchan) {
        switch (owner->type) {
            case OB_ARMATURE:
                type = CONSTRAINT_OBTYPE_BONE;
                break;
            default:
                type = CONSTRAINT_OBTYPE_OBJECT;
                break;
        }
    }
    else
        type = CONSTRAINT_OBTYPE_OBJECT;
    
    /* Get the constraint list for this object */
    switch (type) {
        case CONSTRAINT_OBTYPE_OBJECT:
            conlist = &owner->constraints;
            break;
        case CONSTRAINT_OBTYPE_BONE:
            conlist = &pchan->constraints;
            break;
    }
    
    /* Check all constraints - is constraint valid? */
    if (conlist) {
        for (curcon = conlist->first; curcon; curcon=curcon->next) {
            bConstraintTypeInfo *cti= constraint_get_typeinfo(curcon);
            ListBase targets = {NULL, NULL};
            bConstraintTarget *ct;
            
            /* clear disabled-flag first */
            curcon->flag &= ~CONSTRAINT_DISABLE;
            
            if (curcon->type == CONSTRAINT_TYPE_KINEMATIC) {
                bKinematicConstraint *data = curcon->data;
                
                /* bad: we need a separate set of checks here as poletarget is 
                 *      optional... otherwise poletarget must exist too or else
                 *      the constraint is deemed invalid
                 */
                /* default IK check ... */
                if (exist_object(data->tar) == 0) {
                    data->tar = NULL;
                    curcon->flag |= CONSTRAINT_DISABLE;
                }
                else if (data->tar == owner) {
                    if (!get_named_bone(get_armature(owner), data->subtarget)) {
                        curcon->flag |= CONSTRAINT_DISABLE;
                    }
                }
                
                if (data->poletar) {
                    if (exist_object(data->poletar) == 0) {
                        data->poletar = NULL;
                        curcon->flag |= CONSTRAINT_DISABLE;
                    }
                    else if (data->poletar == owner) {
                        if (!get_named_bone(get_armature(owner), data->polesubtarget)) {
                            curcon->flag |= CONSTRAINT_DISABLE;
                        }
                    }
                }
                /* ... can be overwritten here */
                BIK_test_constraint(owner, curcon);
                /* targets have already been checked for this */
                continue;
            }
            else if (curcon->type == CONSTRAINT_TYPE_PIVOT) {
                bPivotConstraint *data = curcon->data;
                
                /* target doesn't have to exist, but if it is non-null, it must exist! */
                if (data->tar && exist_object(data->tar)==0) {
                    data->tar = NULL;
                    curcon->flag |= CONSTRAINT_DISABLE;
                }
                else if (data->tar == owner) {
                    if (!get_named_bone(get_armature(owner), data->subtarget)) {
                        curcon->flag |= CONSTRAINT_DISABLE;
                    }
                }
                
                /* targets have already been checked for this */
                continue;
            }
            else if (curcon->type == CONSTRAINT_TYPE_ACTION) {
                bActionConstraint *data = curcon->data;
                
                /* validate action */
                if (data->act == NULL) 
                    curcon->flag |= CONSTRAINT_DISABLE;
            }
            else if (curcon->type == CONSTRAINT_TYPE_FOLLOWPATH) {
                bFollowPathConstraint *data = curcon->data;
                
                /* don't allow track/up axes to be the same */
                if (data->upflag==data->trackflag)
                    curcon->flag |= CONSTRAINT_DISABLE;
                if (data->upflag+3==data->trackflag)
                    curcon->flag |= CONSTRAINT_DISABLE;
            }
            else if (curcon->type == CONSTRAINT_TYPE_TRACKTO) {
                bTrackToConstraint *data = curcon->data;
                
                /* don't allow track/up axes to be the same */
                if (data->reserved2==data->reserved1)
                    curcon->flag |= CONSTRAINT_DISABLE;
                if (data->reserved2+3==data->reserved1)
                    curcon->flag |= CONSTRAINT_DISABLE;
            }
            else if (curcon->type == CONSTRAINT_TYPE_LOCKTRACK) {
                bLockTrackConstraint *data = curcon->data;
                
                if (data->lockflag==data->trackflag)
                    curcon->flag |= CONSTRAINT_DISABLE;
                if (data->lockflag+3==data->trackflag)
                    curcon->flag |= CONSTRAINT_DISABLE;
            }
            else if (curcon->type == CONSTRAINT_TYPE_SPLINEIK) {
                bSplineIKConstraint *data = curcon->data;
                
                /* if the number of points does not match the amount required by the chain length,
                 * free the points array and request a rebind...
                 */
                if ((data->points == NULL) || (data->numpoints != data->chainlen+1))
                {
                    /* free the points array */
                    if (data->points) {
                        MEM_freeN(data->points);
                        data->points = NULL;
                    }
                    
                    /* clear the bound flag, forcing a rebind next time this is evaluated */
                    data->flag &= ~CONSTRAINT_SPLINEIK_BOUND;
                }
            }
            else if (curcon->type == CONSTRAINT_TYPE_FOLLOWTRACK) {
                bFollowTrackConstraint *data = curcon->data;

                if((data->flag&CAMERASOLVER_ACTIVECLIP)==0) {
                    if(data->clip != NULL && data->track[0]) {
                        MovieTracking *tracking= &data->clip->tracking;
                        MovieTrackingObject *tracking_object;

                        if(data->object[0])
                            tracking_object= BKE_tracking_named_object(tracking, data->object);
                        else
                            tracking_object= BKE_tracking_get_camera_object(tracking);

                        if(!tracking_object) {
                            curcon->flag |= CONSTRAINT_DISABLE;
                        }
                        else {
                            if (!BKE_tracking_named_track(tracking, tracking_object, data->track))
                                curcon->flag |= CONSTRAINT_DISABLE;
                        }
                    }
                    else curcon->flag |= CONSTRAINT_DISABLE;
                }
            }
            else if (curcon->type == CONSTRAINT_TYPE_CAMERASOLVER) {
                bCameraSolverConstraint *data = curcon->data;

                if((data->flag&CAMERASOLVER_ACTIVECLIP)==0 && data->clip == NULL)
                    curcon->flag |= CONSTRAINT_DISABLE;
            }
            else if (curcon->type == CONSTRAINT_TYPE_OBJECTSOLVER) {
                bObjectSolverConstraint *data = curcon->data;

                if((data->flag&CAMERASOLVER_ACTIVECLIP)==0 && data->clip == NULL)
                    curcon->flag |= CONSTRAINT_DISABLE;
            }
            
            /* Check targets for constraints */
            if (cti && cti->get_constraint_targets) {
                cti->get_constraint_targets(curcon, &targets);
                
                /* disable and clear constraints targets that are incorrect */
                for (ct= targets.first; ct; ct= ct->next) {
                    /* general validity checks (for those constraints that need this) */
                    if (exist_object(ct->tar) == 0) {
                        /* object doesn't exist, but constraint requires target */
                        ct->tar = NULL;
                        curcon->flag |= CONSTRAINT_DISABLE;
                    }
                    else if (ct->tar == owner) {
                        if (type == CONSTRAINT_OBTYPE_BONE) {
                            if (!get_named_bone(get_armature(owner), ct->subtarget)) {
                                /* bone must exist in armature... */
                                // TODO: clear subtarget?
                                curcon->flag |= CONSTRAINT_DISABLE;
                            }
                            else if (strcmp(pchan->name, ct->subtarget) == 0) {
                                /* cannot target self */
                                ct->subtarget[0] = '\0';
                                curcon->flag |= CONSTRAINT_DISABLE;
                            }
                        }
                        else {
                            /* cannot use self as target */
                            ct->tar = NULL;
                            curcon->flag |= CONSTRAINT_DISABLE;
                        }
                    }
                    
                    /* target checks for specific constraints */
                    if (ELEM3(curcon->type, CONSTRAINT_TYPE_FOLLOWPATH, CONSTRAINT_TYPE_CLAMPTO, CONSTRAINT_TYPE_SPLINEIK)) {
                        if (ct->tar) {
                            if (ct->tar->type != OB_CURVE) {
                                ct->tar= NULL;
                                curcon->flag |= CONSTRAINT_DISABLE;
                            }
                            else {
                                Curve *cu= ct->tar->data;
                                
                                /* auto-set 'Path' setting on curve so this works  */
                                cu->flag |= CU_PATH;
                            }
                        }                       
                    }
                }   
                
                /* free any temporary targets */
                if (cti->flush_constraint_targets)
                    cti->flush_constraint_targets(curcon, &targets, 0);
            }
        }
    }
}

void object_test_constraints (Object *owner)
{
    if (owner->constraints.first)
        test_constraints(owner, NULL);
    
    if (owner->type==OB_ARMATURE && owner->pose) {
        bPoseChannel *pchan;
        
        for (pchan= owner->pose->chanbase.first; pchan; pchan= pchan->next) {
            if (pchan->constraints.first)
                test_constraints(owner, pchan);
        }
    }
}


/************************ generic functions for operators using constraint names and data context *********************/

#define EDIT_CONSTRAINT_OWNER_OBJECT    0
#define EDIT_CONSTRAINT_OWNER_BONE      1

static EnumPropertyItem constraint_owner_items[] = {
    {EDIT_CONSTRAINT_OWNER_OBJECT, "OBJECT", 0, "Object", "Edit a constraint on the active object"},
    {EDIT_CONSTRAINT_OWNER_BONE, "BONE", 0, "Bone", "Edit a constraint on the active bone"},
    {0, NULL, 0, NULL, NULL}};


static int edit_constraint_poll_generic(bContext *C, StructRNA *rna_type)
{
    PointerRNA ptr= CTX_data_pointer_get_type(C, "constraint", rna_type);
    Object *ob= (ptr.id.data) ? ptr.id.data : ED_object_active_context(C);

    if (!ob || ob->id.lib) return 0;
    if (ptr.id.data && ((ID*)ptr.id.data)->lib) return 0;

    return 1;
}

static int edit_constraint_poll(bContext *C)
{
    return edit_constraint_poll_generic(C, &RNA_Constraint);
}

static void edit_constraint_properties(wmOperatorType *ot)
{
    RNA_def_string(ot->srna, "constraint", "", MAX_NAME, "Constraint", "Name of the constraint to edit");
    RNA_def_enum(ot->srna, "owner", constraint_owner_items, 0, "Owner", "The owner of this constraint");
}

static int edit_constraint_invoke_properties(bContext *C, wmOperator *op)
{
    PointerRNA ptr= CTX_data_pointer_get_type(C, "constraint", &RNA_Constraint);
    Object *ob= (ptr.id.data)?ptr.id.data:ED_object_active_context(C);
    bConstraint *con;
    ListBase *list;
    
    if (RNA_struct_property_is_set(op->ptr, "constraint") && RNA_struct_property_is_set(op->ptr, "owner"))
        return 1;
    
    if (ptr.data) {
        con = ptr.data;
        RNA_string_set(op->ptr, "constraint", con->name);
        
        list = get_constraint_lb(ob, con, NULL);
        
        if (&ob->constraints == list)
            RNA_enum_set(op->ptr, "owner", EDIT_CONSTRAINT_OWNER_OBJECT);
        else
            RNA_enum_set(op->ptr, "owner", EDIT_CONSTRAINT_OWNER_BONE);
        
        return 1;
    }
    
    return 0;
}

static bConstraint *edit_constraint_property_get(wmOperator *op, Object *ob, int type)
{
    char constraint_name[MAX_NAME];
    int owner = RNA_enum_get(op->ptr, "owner");
    bConstraint *con;
    ListBase *list=NULL;
    
    RNA_string_get(op->ptr, "constraint", constraint_name);
    
    if (owner == EDIT_CONSTRAINT_OWNER_OBJECT) {
        list = &ob->constraints;
    } 
    else if (owner == EDIT_CONSTRAINT_OWNER_BONE) {
        bPoseChannel *pchan= get_active_posechannel(ob);
        if (pchan)
            list = &pchan->constraints;
        else {
            //if (G.f & G_DEBUG)
            //printf("edit_constraint_property_get: No active bone for object '%s'\n", (ob)? ob->id.name+2 : "<None>");
            return NULL;
        }
    }
    else {
        //if (G.f & G_DEBUG)
        //printf("edit_constraint_property_get: defaulting to getting list in the standard way\n");
        list = get_active_constraints(ob);
    }
    
    con = constraints_findByName(list, constraint_name);
    //if (G.f & G_DEBUG)
    //printf("constraint found = %p, %s\n", (void *)con, (con)?con->name:"<Not found>");

    if (con && (type != 0) && (con->type != type))
        con = NULL;
    
    return con;
}

/* ********************** CONSTRAINT-SPECIFIC STUFF ********************* */

/* ---------- Distance-Dependent Constraints ---------- */
/* StretchTo, Limit Distance */

static int stretchto_reset_exec (bContext *C, wmOperator *op)
{
    Object *ob = ED_object_active_context(C);
    bConstraint *con = edit_constraint_property_get(op, ob, CONSTRAINT_TYPE_STRETCHTO);
    bStretchToConstraint *data= (con) ? (bStretchToConstraint *)con->data : NULL;
    
    /* despite 3 layers of checks, we may still not be able to find a constraint */
    if (data == NULL)
        return OPERATOR_CANCELLED;
    
    /* just set original length to 0.0, which will cause a reset on next recalc */
    data->orglength = 0.0f;
    ED_object_constraint_update(ob);
    
    WM_event_add_notifier(C, NC_OBJECT|ND_CONSTRAINT, NULL);
    return OPERATOR_FINISHED;
}

static int stretchto_reset_invoke(bContext *C, wmOperator *op, wmEvent *UNUSED(event))
{
    if (edit_constraint_invoke_properties(C, op))
        return stretchto_reset_exec(C, op);
    else
        return OPERATOR_CANCELLED;
}

void CONSTRAINT_OT_stretchto_reset (wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Reset Original Length";
    ot->idname= "CONSTRAINT_OT_stretchto_reset";
    ot->description= "Reset original length of bone for Stretch To Constraint";
    
    ot->exec= stretchto_reset_exec;
    ot->invoke= stretchto_reset_invoke;
    ot->poll= edit_constraint_poll;
    
    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO;
    edit_constraint_properties(ot);
}


static int limitdistance_reset_exec (bContext *C, wmOperator *op)
{
    Object *ob = ED_object_active_context(C);
    bConstraint *con = edit_constraint_property_get(op, ob, CONSTRAINT_TYPE_DISTLIMIT);
    bDistLimitConstraint *data= (con) ? (bDistLimitConstraint *)con->data : NULL;
    
    /* despite 3 layers of checks, we may still not be able to find a constraint */
    if (data == NULL)
        return OPERATOR_CANCELLED;
    
    /* just set original length to 0.0, which will cause a reset on next recalc */
    data->dist = 0.0f;
    ED_object_constraint_update(ob);
    
    WM_event_add_notifier(C, NC_OBJECT|ND_CONSTRAINT, NULL);
    return OPERATOR_FINISHED;
}

static int limitdistance_reset_invoke(bContext *C, wmOperator *op, wmEvent *UNUSED(event))
{
    if (edit_constraint_invoke_properties(C, op))
        return limitdistance_reset_exec(C, op);
    else
        return OPERATOR_CANCELLED;
}

void CONSTRAINT_OT_limitdistance_reset (wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Reset Distance";
    ot->idname= "CONSTRAINT_OT_limitdistance_reset";
    ot->description= "Reset limiting distance for Limit Distance Constraint";
    
    ot->exec= limitdistance_reset_exec;
    ot->invoke= limitdistance_reset_invoke;
    ot->poll= edit_constraint_poll;
    
    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO;
    edit_constraint_properties(ot);
}

/* ------------- Child-Of Constraint ------------------ */

static void child_get_inverse_matrix (Scene *scene, Object *ob, bConstraint *con, float invmat[4][4])
{
    bConstraint *lastcon = NULL;
    bPoseChannel *pchan= NULL;
    
    /* nullify inverse matrix first */
    unit_m4(invmat);
    
    /* try to find a pose channel - assume that this is the constraint owner */
    // TODO: get from context instead?
    if (ob && ob->pose)
        pchan= get_active_posechannel(ob);
    
    /* calculate/set inverse matrix:
     *  We just calculate all transform-stack eval up to but not including this constraint.
     *  This is because inverse should just inverse correct for just the constraint's influence
     *  when it gets applied; that is, at the time of application, we don't know anything about
     *  what follows.
     */
    if (pchan) {
        float imat[4][4], tmat[4][4];
        float pmat[4][4];
        
        /* 1. calculate posemat where inverse doesn't exist yet (inverse was cleared above), 
         * to use as baseline ("pmat") to derive delta from. This extra calc saves users 
         * from having pressing "Clear Inverse" first
         */
        where_is_pose(scene, ob);
        copy_m4_m4(pmat, pchan->pose_mat);
        
        /* 2. knock out constraints starting from this one */
        lastcon = pchan->constraints.last;
        pchan->constraints.last = con->prev;
        
        if (con->prev) {
            /* new end must not point to this one, else this chain cutting is useless */
            con->prev->next = NULL;
        }
        else {
            /* constraint was first */
            pchan->constraints.first = NULL;
        }
        
        /* 3. solve pose without disabled constraints */
        where_is_pose(scene, ob);
        
        /* 4. determine effect of constraint by removing the newly calculated 
         * pchan->pose_mat from the original pchan->pose_mat, thus determining 
         * the effect of the constraint
         */
        invert_m4_m4(imat, pchan->pose_mat);
        mult_m4_m4m4(tmat, pmat, imat);
        invert_m4_m4(invmat, tmat);
        
        /* 5. restore constraints */
        pchan->constraints.last = lastcon;
        
        if (con->prev) {
            /* hook up prev to this one again */
            con->prev->next = con;
        }
        else {
            /* set as first again */
            pchan->constraints.first = con;
        }
        
        /* 6. recalculate pose with new inv-mat applied */
        where_is_pose(scene, ob);
    }
    else if (ob) {
        Object workob;
        
        /* use what_does_parent to find inverse - just like for normal parenting */
        what_does_parent(scene, ob, &workob);
        invert_m4_m4(invmat, workob.obmat);
    }
}

/* ChildOf Constraint - set inverse callback */
static int childof_set_inverse_exec (bContext *C, wmOperator *op)
{
    Scene *scene= CTX_data_scene(C);
    Object *ob = ED_object_active_context(C);
    bConstraint *con = edit_constraint_property_get(op, ob, CONSTRAINT_TYPE_CHILDOF);
    bChildOfConstraint *data= (con) ? (bChildOfConstraint *)con->data : NULL;

    /* despite 3 layers of checks, we may still not be able to find a constraint */
    if (data == NULL) {
        printf("DEBUG: Child-Of Set Inverse - object = '%s'\n", (ob)? ob->id.name+2 : "<None>");
        BKE_report(op->reports, RPT_ERROR, "Couldn't find constraint data for Child-Of Set Inverse");
        return OPERATOR_CANCELLED;
    }
    
    child_get_inverse_matrix(scene, ob, con, data->invmat);

    WM_event_add_notifier(C, NC_OBJECT|ND_CONSTRAINT, ob);
    
    return OPERATOR_FINISHED;
}

static int childof_set_inverse_invoke(bContext *C, wmOperator *op, wmEvent *UNUSED(event))
{
    if (edit_constraint_invoke_properties(C, op))
        return childof_set_inverse_exec(C, op);
    else
        return OPERATOR_CANCELLED;
}

void CONSTRAINT_OT_childof_set_inverse (wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Set Inverse";
    ot->idname= "CONSTRAINT_OT_childof_set_inverse";
    ot->description= "Set inverse correction for ChildOf constraint";
    
    ot->exec= childof_set_inverse_exec;
    ot->invoke= childof_set_inverse_invoke;
    ot->poll= edit_constraint_poll;
    
    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO;
    edit_constraint_properties(ot);
}

/* ChildOf Constraint - clear inverse callback */
static int childof_clear_inverse_exec (bContext *C, wmOperator *op)
{
    Object *ob = ED_object_active_context(C);
    bConstraint *con = edit_constraint_property_get(op, ob, CONSTRAINT_TYPE_CHILDOF);
    bChildOfConstraint *data= (con) ? (bChildOfConstraint *)con->data : NULL;
    
    if(data==NULL) {
        BKE_report(op->reports, RPT_ERROR, "Childof constraint not found");
        return OPERATOR_CANCELLED;
    }
    
    /* simply clear the matrix */
    unit_m4(data->invmat);
    
    WM_event_add_notifier(C, NC_OBJECT|ND_CONSTRAINT, ob);
    
    return OPERATOR_FINISHED;
}

static int childof_clear_inverse_invoke(bContext *C, wmOperator *op, wmEvent *UNUSED(event))
{
    if (edit_constraint_invoke_properties(C, op))
        return childof_clear_inverse_exec(C, op);
    else
        return OPERATOR_CANCELLED;
}

void CONSTRAINT_OT_childof_clear_inverse (wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Clear Inverse";
    ot->idname= "CONSTRAINT_OT_childof_clear_inverse";
    ot->description= "Clear inverse correction for ChildOf constraint";
    
    ot->exec= childof_clear_inverse_exec;
    ot->invoke= childof_clear_inverse_invoke;
    ot->poll= edit_constraint_poll;
    
    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO;
    edit_constraint_properties(ot);
}

/* ------------- Object Solver Constraint ------------------ */

static int objectsolver_set_inverse_exec (bContext *C, wmOperator *op)
{
    Scene *scene= CTX_data_scene(C);
    Object *ob = ED_object_active_context(C);
    bConstraint *con = edit_constraint_property_get(op, ob, CONSTRAINT_TYPE_OBJECTSOLVER);
    bObjectSolverConstraint *data= (con) ? (bObjectSolverConstraint *)con->data : NULL;

    /* despite 3 layers of checks, we may still not be able to find a constraint */
    if (data == NULL) {
        printf("DEBUG: Child-Of Set Inverse - object = '%s'\n", (ob)? ob->id.name+2 : "<None>");
        BKE_report(op->reports, RPT_ERROR, "Couldn't find constraint data for Child-Of Set Inverse");
        return OPERATOR_CANCELLED;
    }

    child_get_inverse_matrix(scene, ob, con, data->invmat);

    WM_event_add_notifier(C, NC_OBJECT|ND_CONSTRAINT, ob);

    return OPERATOR_FINISHED;
}

static int objectsolver_set_inverse_invoke(bContext *C, wmOperator *op, wmEvent *UNUSED(event))
{
    if (edit_constraint_invoke_properties(C, op))
        return objectsolver_set_inverse_exec(C, op);
    else
        return OPERATOR_CANCELLED;
}

void CONSTRAINT_OT_objectsolver_set_inverse (wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Set Inverse";
    ot->idname= "CONSTRAINT_OT_objectsolver_set_inverse";
    ot->description= "Set inverse correction for ObjectSolver constraint";

    ot->exec= objectsolver_set_inverse_exec;
    ot->invoke= objectsolver_set_inverse_invoke;
    ot->poll= edit_constraint_poll;

    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO;
    edit_constraint_properties(ot);
}

static int objectsolver_clear_inverse_exec (bContext *C, wmOperator *op)
{
    Object *ob = ED_object_active_context(C);
    bConstraint *con = edit_constraint_property_get(op, ob, CONSTRAINT_TYPE_OBJECTSOLVER);
    bObjectSolverConstraint *data= (con) ? (bObjectSolverConstraint *)con->data : NULL;

    if(data==NULL) {
        BKE_report(op->reports, RPT_ERROR, "Childof constraint not found");
        return OPERATOR_CANCELLED;
    }

    /* simply clear the matrix */
    unit_m4(data->invmat);

    WM_event_add_notifier(C, NC_OBJECT|ND_CONSTRAINT, ob);

    return OPERATOR_FINISHED;
}

static int objectsolver_clear_inverse_invoke(bContext *C, wmOperator *op, wmEvent *UNUSED(event))
{
    if (edit_constraint_invoke_properties(C, op))
        return objectsolver_clear_inverse_exec(C, op);
    else
        return OPERATOR_CANCELLED;
}

void CONSTRAINT_OT_objectsolver_clear_inverse (wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Clear Inverse";
    ot->idname= "CONSTRAINT_OT_objectsolver_clear_inverse";
    ot->description= "Clear inverse correction for ObjectSolver constraint";

    ot->exec= objectsolver_clear_inverse_exec;
    ot->invoke= objectsolver_clear_inverse_invoke;
    ot->poll= edit_constraint_poll;

    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO;
    edit_constraint_properties(ot);
}

/***************************** BUTTONS ****************************/

void ED_object_constraint_set_active(Object *ob, bConstraint *con)
{   
    ListBase *lb = get_constraint_lb(ob, con, NULL);
    
    /* lets be nice and escape if its active already */
    // NOTE: this assumes that the stack doesn't have other active ones set...
    if ((lb && con) && (con->flag & CONSTRAINT_ACTIVE))
        return;
    
    constraints_set_active(lb, con);
}

void ED_object_constraint_update(Object *ob)
{

    if(ob->pose) update_pose_constraint_flags(ob->pose);

    object_test_constraints(ob);

    if(ob->type==OB_ARMATURE) DAG_id_tag_update(&ob->id, OB_RECALC_DATA|OB_RECALC_OB);
    else DAG_id_tag_update(&ob->id, OB_RECALC_OB);
}

void ED_object_constraint_dependency_update(Main *bmain, Scene *scene, Object *ob)
{
    ED_object_constraint_update(ob);

    if(ob->pose) ob->pose->flag |= POSE_RECALC; // checks & sorts pose channels
    DAG_scene_sort(bmain, scene);
}

static int constraint_poll(bContext *C)
{
    PointerRNA ptr= CTX_data_pointer_get_type(C, "constraint", &RNA_Constraint);
    return (ptr.id.data && ptr.data);
}

static int constraint_delete_exec (bContext *C, wmOperator *UNUSED(op))
{
    PointerRNA ptr= CTX_data_pointer_get_type(C, "constraint", &RNA_Constraint);
    Object *ob= ptr.id.data;
    bConstraint *con= ptr.data;
    ListBase *lb = get_constraint_lb(ob, con, NULL);
    const short is_ik= ELEM(con->type, CONSTRAINT_TYPE_KINEMATIC, CONSTRAINT_TYPE_SPLINEIK);

    /* free the constraint */
    if (remove_constraint(lb, con)) {
        /* there's no active constraint now, so make sure this is the case */
        constraints_set_active(lb, NULL);
        
        ED_object_constraint_update(ob); /* needed to set the flags on posebones correctly */

        /* ITASC needs to be rebuilt once a constraint is removed [#26920] */
        if(is_ik) {
            BIK_clear_data(ob->pose);
        }

        /* notifiers */
        WM_event_add_notifier(C, NC_OBJECT|ND_CONSTRAINT|NA_REMOVED, ob);
        
        return OPERATOR_FINISHED;
    }
    else {
        /* couldn't remove due to some invalid data */
        return OPERATOR_CANCELLED;
    }
}

void CONSTRAINT_OT_delete (wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Delete Constraint";
    ot->idname= "CONSTRAINT_OT_delete";
    ot->description= "Remove constraint from constraint stack";
    
    /* callbacks */
    ot->exec= constraint_delete_exec;
    ot->poll= constraint_poll;
    
    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO; 
}

static int constraint_move_down_exec (bContext *C, wmOperator *op)
{
    Object *ob = ED_object_active_context(C);
    bConstraint *con = edit_constraint_property_get(op, ob, 0);
    
    if (con && con->next) {
        ListBase *conlist= get_constraint_lb(ob, con, NULL);
        bConstraint *nextCon= con->next;
        
        /* insert the nominated constraint after the one that used to be after it */
        BLI_remlink(conlist, con);
        BLI_insertlinkafter(conlist, nextCon, con);
        
        WM_event_add_notifier(C, NC_OBJECT|ND_CONSTRAINT, ob);
        
        return OPERATOR_FINISHED;
    }
    
    return OPERATOR_CANCELLED;
}

static int constraint_move_down_invoke(bContext *C, wmOperator *op, wmEvent *UNUSED(event))
{
    if (edit_constraint_invoke_properties(C, op))
        return constraint_move_down_exec(C, op);
    else
        return OPERATOR_CANCELLED;
}


void CONSTRAINT_OT_move_down (wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Move Constraint Down";
    ot->idname= "CONSTRAINT_OT_move_down";
    ot->description= "Move constraint down in constraint stack";
    
    /* callbacks */
    ot->exec= constraint_move_down_exec;
    ot->invoke= constraint_move_down_invoke;
    ot->poll= edit_constraint_poll;
    
    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO; 
    edit_constraint_properties(ot);
}


static int constraint_move_up_exec (bContext *C, wmOperator *op)
{
    Object *ob = ED_object_active_context(C);
    bConstraint *con = edit_constraint_property_get(op, ob, 0);
    
    if (con && con->prev) {
        ListBase *conlist= get_constraint_lb(ob, con, NULL);
        bConstraint *prevCon= con->prev;
        
        /* insert the nominated constraint before the one that used to be before it */
        BLI_remlink(conlist, con);
        BLI_insertlinkbefore(conlist, prevCon, con);
        
        WM_event_add_notifier(C, NC_OBJECT|ND_CONSTRAINT, ob);
        
        return OPERATOR_FINISHED;
    }
    
    return OPERATOR_CANCELLED;
}

static int constraint_move_up_invoke(bContext *C, wmOperator *op, wmEvent *UNUSED(event))
{
    if (edit_constraint_invoke_properties(C, op))
        return constraint_move_up_exec(C, op);
    else
        return OPERATOR_CANCELLED;
}

void CONSTRAINT_OT_move_up (wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Move Constraint Up";
    ot->idname= "CONSTRAINT_OT_move_up";
    ot->description= "Move constraint up in constraint stack";
    
    /* callbacks */
    ot->exec= constraint_move_up_exec;
    ot->invoke= constraint_move_up_invoke;
    ot->poll= edit_constraint_poll;
    
    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO; 
    edit_constraint_properties(ot);
}

/***************************** OPERATORS ****************************/

/************************ remove constraint operators *********************/

static int pose_constraints_clear_exec(bContext *C, wmOperator *UNUSED(op))
{
    Main *bmain= CTX_data_main(C);
    Scene *scene= CTX_data_scene(C);
    Object *ob= object_pose_armature_get(CTX_data_active_object(C));
    
    /* free constraints for all selected bones */
    CTX_DATA_BEGIN(C, bPoseChannel*, pchan, selected_pose_bones)
    {
        free_constraints(&pchan->constraints);
        pchan->constflag &= ~(PCHAN_HAS_IK|PCHAN_HAS_SPLINEIK|PCHAN_HAS_CONST);
    }
    CTX_DATA_END;
    
    /* force depsgraph to get recalculated since relationships removed */
    DAG_scene_sort(bmain, scene);       /* sort order of objects */ 
    
    /* note, calling BIK_clear_data() isnt needed here */

    /* do updates */
    DAG_id_tag_update(&ob->id, OB_RECALC_DATA);
    WM_event_add_notifier(C, NC_OBJECT|ND_CONSTRAINT, ob);
    
    return OPERATOR_FINISHED;
}

void POSE_OT_constraints_clear(wmOperatorType *ot)
{
    /* identifiers */
    ot->name = "Clear Pose Constraints";
    ot->idname= "POSE_OT_constraints_clear";
    ot->description= "Clear all the constraints for the selected bones";
    
    /* callbacks */
    ot->exec= pose_constraints_clear_exec;
    ot->poll= ED_operator_posemode; // XXX - do we want to ensure there are selected bones too?
}


static int object_constraints_clear_exec(bContext *C, wmOperator *UNUSED(op))
{
    Main *bmain= CTX_data_main(C);
    Scene *scene= CTX_data_scene(C);
    
    /* do freeing */
    CTX_DATA_BEGIN(C, Object*, ob, selected_editable_objects) 
    {
        free_constraints(&ob->constraints);
        DAG_id_tag_update(&ob->id, OB_RECALC_OB);
    }
    CTX_DATA_END;
    
    /* force depsgraph to get recalculated since relationships removed */
    DAG_scene_sort(bmain, scene);       /* sort order of objects */ 
    
    /* do updates */
    WM_event_add_notifier(C, NC_OBJECT|ND_CONSTRAINT, NULL);
    
    return OPERATOR_FINISHED;
}

void OBJECT_OT_constraints_clear(wmOperatorType *ot)
{
    /* identifiers */
    ot->name = "Clear Object Constraints";
    ot->idname= "OBJECT_OT_constraints_clear";
    ot->description= "Clear all the constraints for the active Object only";
    
    /* callbacks */
    ot->exec= object_constraints_clear_exec;
    ot->poll= ED_operator_object_active_editable;
}

/************************ copy all constraints operators *********************/

static int pose_constraint_copy_exec(bContext *C, wmOperator *op)
{
    Main *bmain= CTX_data_main(C);
    Scene *scene = CTX_data_scene(C);
    bPoseChannel *pchan = CTX_data_active_pose_bone(C);
    
    /* don't do anything if bone doesn't exist or doesn't have any constraints */
    if (ELEM(NULL, pchan, pchan->constraints.first)) {
        BKE_report(op->reports, RPT_ERROR, "No active bone with constraints for copying");
        return OPERATOR_CANCELLED;
    }
    
    /* copy all constraints from active posebone to all selected posebones */
    CTX_DATA_BEGIN(C, bPoseChannel*, chan, selected_pose_bones) 
    {
        /* if we're not handling the object we're copying from, copy all constraints over */
        if (pchan != chan) {
            copy_constraints(&chan->constraints, &pchan->constraints, TRUE);
            /* update flags (need to add here, not just copy) */
            chan->constflag |= pchan->constflag;
        }
    }
    CTX_DATA_END;
    
    /* force depsgraph to get recalculated since new relationships added */
    DAG_scene_sort(bmain, scene);       /* sort order of objects/bones */

    WM_event_add_notifier(C, NC_OBJECT|ND_CONSTRAINT, NULL);
    
    return OPERATOR_FINISHED;
}

void POSE_OT_constraints_copy(wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Copy Constraints to Selected";
    ot->idname= "POSE_OT_constraints_copy";
    ot->description = "Copy constraints to other selected bones";
    
    /* api callbacks */
    ot->exec= pose_constraint_copy_exec;
    ot->poll= ED_operator_posemode;

    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO;
}

static int object_constraint_copy_exec(bContext *C, wmOperator *UNUSED(op))
{
    Main *bmain= CTX_data_main(C);
    Scene *scene = CTX_data_scene(C);
    Object *obact = ED_object_active_context(C);
    
    /* copy all constraints from active object to all selected objects */
    CTX_DATA_BEGIN(C, Object*, ob, selected_editable_objects) 
    {
        /* if we're not handling the object we're copying from, copy all constraints over */
        if (obact != ob) {
            copy_constraints(&ob->constraints, &obact->constraints, TRUE);
            DAG_id_tag_update(&ob->id, OB_RECALC_DATA);
        }
    }
    CTX_DATA_END;
    
    /* force depsgraph to get recalculated since new relationships added */
    DAG_scene_sort(bmain, scene);       /* sort order of objects */
    
    /* notifiers for updates */
    WM_event_add_notifier(C, NC_OBJECT|ND_CONSTRAINT|NA_ADDED, NULL);
    
    return OPERATOR_FINISHED;
}

void OBJECT_OT_constraints_copy(wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Copy Constraints to Selected";
    ot->idname= "OBJECT_OT_constraints_copy";
    ot->description = "Copy constraints to other selected objects";
    
    /* api callbacks */
    ot->exec= object_constraint_copy_exec;
    ot->poll= ED_operator_object_active_editable;

    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO;
}

/************************ add constraint operators *********************/

/* get the Object and/or PoseChannel to use as target */
static short get_new_constraint_target(bContext *C, int con_type, Object **tar_ob, bPoseChannel **tar_pchan, short add)
{
    Object *obact= ED_object_active_context(C);
    bPoseChannel *pchanact= get_active_posechannel(obact);
    short only_curve= 0, only_mesh= 0, only_ob= 0;
    short found= 0;
    
    /* clear tar_ob and tar_pchan fields before use 
     *  - assume for now that both always exist...
     */
    *tar_ob= NULL;
    *tar_pchan= NULL;
    
    /* check if constraint type doesn't requires a target
     *  - if so, no need to get any targets 
     */
    switch (con_type) {
        /* no-target constraints --------------------------- */
            /* null constraint - shouldn't even be added! */
        case CONSTRAINT_TYPE_NULL:
            /* limit constraints - no targets needed */
        case CONSTRAINT_TYPE_LOCLIMIT:
        case CONSTRAINT_TYPE_ROTLIMIT:
        case CONSTRAINT_TYPE_SIZELIMIT:
        case CONSTRAINT_TYPE_SAMEVOL:
            return 0;
            
        /* restricted target-type constraints -------------- */
        /* NOTE: for these, we cannot try to add a target object if no valid ones are found, since that doesn't work */
            /* curve-based constraints - set the only_curve and only_ob flags */
        case CONSTRAINT_TYPE_CLAMPTO:
        case CONSTRAINT_TYPE_FOLLOWPATH:
        case CONSTRAINT_TYPE_SPLINEIK:
            only_curve= 1;
            only_ob= 1;
            add= 0;
            break;
            
            /* mesh only? */
        case CONSTRAINT_TYPE_SHRINKWRAP:
            only_mesh= 1;
            only_ob= 1;
            add= 0;
            break;
            
            /* object only - add here is ok? */
        case CONSTRAINT_TYPE_RIGIDBODYJOINT:
            only_ob= 1;
            break;
    }
    
    /* if the active Object is Armature, and we can search for bones, do so... */
    if ((obact->type == OB_ARMATURE) && (only_ob == 0)) {
        /* search in list of selected Pose-Channels for target */
        CTX_DATA_BEGIN(C, bPoseChannel*, pchan, selected_pose_bones) 
        {
            /* just use the first one that we encounter, as long as it is not the active one */
            if (pchan != pchanact) {
                *tar_ob= obact;
                *tar_pchan= pchan;
                found= 1;
                
                break;
            }
        }
        CTX_DATA_END;
    }
    
    /* if not yet found, try selected Objects... */
    if (found == 0) {
        /* search in selected objects context */
        CTX_DATA_BEGIN(C, Object*, ob, selected_objects) 
        {
            /* just use the first object we encounter (that isn't the active object) 
             * and which fulfills the criteria for the object-target that we've got 
             */
            if ( (ob != obact) &&
                 ((!only_curve) || (ob->type == OB_CURVE)) && 
                 ((!only_mesh) || (ob->type == OB_MESH)) )
            {
                /* set target */
                *tar_ob= ob;
                found= 1;
                
                /* perform some special operations on the target */
                if (only_curve) {
                    /* Curve-Path option must be enabled for follow-path constraints to be able to work */
                    Curve *cu= (Curve *)ob->data;
                    cu->flag |= CU_PATH;
                }
                
                break;
            }
        }
        CTX_DATA_END;
    }
    
    /* if still not found, add a new empty to act as a target (if allowed) */
    if ((found == 0) && (add)) {
        Scene *scene= CTX_data_scene(C);
        Base *base= BASACT, *newbase=NULL;
        Object *obt;
        
        /* add new target object */
        obt= add_object(scene, OB_EMPTY);
        
        /* set layers OK */
        newbase= BASACT;
        newbase->lay= base->lay;
        obt->lay= newbase->lay;
        
        /* transform cent to global coords for loc */
        if (pchanact) {
            /* since by default, IK targets the tip of the last bone, use the tip of the active PoseChannel 
             * if adding a target for an IK Constraint
             */
            if (con_type == CONSTRAINT_TYPE_KINEMATIC)
                mul_v3_m4v3(obt->loc, obact->obmat, pchanact->pose_tail);
            else
                mul_v3_m4v3(obt->loc, obact->obmat, pchanact->pose_head);
        }
        else {
            copy_v3_v3(obt->loc, obact->obmat[3]);
        }

        /* restore, add_object sets active */
        BASACT= base;
        base->flag |= SELECT;
        
        /* make our new target the new object */
        *tar_ob= obt;
        found= 1;
    }
    
    /* return whether there's any target */
    return found;
}

/* used by add constraint operators to add the constraint required */
static int constraint_add_exec(bContext *C, wmOperator *op, Object *ob, ListBase *list, int type, short setTarget)
{
    Main *bmain= CTX_data_main(C);
    Scene *scene= CTX_data_scene(C);
    bPoseChannel *pchan;
    bConstraint *con;
    
    if (list == &ob->constraints) {
        pchan= NULL;
    }
    else {
        pchan= get_active_posechannel(ob);
        
        /* ensure not to confuse object/pose adding */
        if (pchan == NULL) {
            BKE_report(op->reports, RPT_ERROR, "No active pose bone to add a constraint to");
            return OPERATOR_CANCELLED;
        }
    }
    /* check if constraint to be added is valid for the given constraints stack */
    if (type == CONSTRAINT_TYPE_NULL) {
        return OPERATOR_CANCELLED;
    }
    if ( (type == CONSTRAINT_TYPE_RIGIDBODYJOINT) && (list != &ob->constraints) ) {
        BKE_report(op->reports, RPT_ERROR, "Rigid Body Joint Constraint can only be added to Objects");
        return OPERATOR_CANCELLED;
    }
    if ( (type == CONSTRAINT_TYPE_KINEMATIC) && ((!pchan) || (list != &pchan->constraints)) ) {
        BKE_report(op->reports, RPT_ERROR, "IK Constraint can only be added to Bones");
        return OPERATOR_CANCELLED;
    }
    if ( (type == CONSTRAINT_TYPE_SPLINEIK) && ((!pchan) || (list != &pchan->constraints)) ) {
        BKE_report(op->reports, RPT_ERROR, "Spline IK Constraint can only be added to Bones");
        return OPERATOR_CANCELLED;
    }
    
    /* create a new constraint of the type requried, and add it to the active/given constraints list */
    if (pchan)
        con = add_pose_constraint(ob, pchan, NULL, type);
    else
        con = add_ob_constraint(ob, NULL, type);
    
    /* get the first selected object/bone, and make that the target
     *  - apart from the buttons-window add buttons, we shouldn't add in this way
     */
    if (setTarget) {
        Object *tar_ob= NULL;
        bPoseChannel *tar_pchan= NULL;
        
        /* get the target objects, adding them as need be */
        if (get_new_constraint_target(C, type, &tar_ob, &tar_pchan, 1)) {
            /* method of setting target depends on the type of target we've got 
             *  - by default, just set the first target (distinction here is only for multiple-targetted constraints)
             */
            if (tar_pchan)
                set_constraint_nth_target(con, tar_ob, tar_pchan->name, 0);
            else
                set_constraint_nth_target(con, tar_ob, "", 0);
        }
    }
    
    /* do type-specific tweaking to the constraint settings  */
    switch (type) {
        case CONSTRAINT_TYPE_PYTHON: // FIXME: this code is not really valid anymore
        {
#ifdef WITH_PYTHON
            char *menustr;
            int scriptint= 0;
            /* popup a list of usable scripts */
            menustr = buildmenu_pyconstraints(NULL, &scriptint);
            // XXX scriptint = pupmenu(menustr);
            MEM_freeN(menustr);
            
            /* only add constraint if a script was chosen */
            if (scriptint) {
                /* add constraint */
                validate_pyconstraint_cb(con->data, &scriptint);
                
                /* make sure target allowance is set correctly */
                BPY_pyconstraint_update(ob, con);
            }
#endif
            break;
        }

        default:
            break;
    }
    
    /* make sure all settings are valid - similar to above checks, but sometimes can be wrong */
    object_test_constraints(ob);

    if (pchan)
        update_pose_constraint_flags(ob->pose);


    /* force depsgraph to get recalculated since new relationships added */
    DAG_scene_sort(bmain, scene);       /* sort order of objects */
    
    if ((ob->type==OB_ARMATURE) && (pchan)) {
        ob->pose->flag |= POSE_RECALC;  /* sort pose channels */
        DAG_id_tag_update(&ob->id, OB_RECALC_DATA|OB_RECALC_OB);
    }
    else
        DAG_id_tag_update(&ob->id, OB_RECALC_DATA);
    
    /* notifiers for updates */
    WM_event_add_notifier(C, NC_OBJECT|ND_CONSTRAINT|NA_ADDED, ob);
    
    return OPERATOR_FINISHED;
}

/* ------------------ */

/* dummy operator callback */
static int object_constraint_add_exec(bContext *C, wmOperator *op)
{
    Object *ob=ED_object_active_context(C);
    int type= RNA_enum_get(op->ptr, "type");
    short with_targets= 0;
    
    if (!ob) {
        BKE_report(op->reports, RPT_ERROR, "No active object to add constraint to");
        return OPERATOR_CANCELLED;
    }
        
    /* hack: set constraint targets from selected objects in context is allowed when
     *      operator name included 'with_targets', since the menu doesn't allow multiple properties
     */
    if (strstr(op->idname, "with_targets"))
        with_targets= 1;

    return constraint_add_exec(C, op, ob, &ob->constraints, type, with_targets);
}

/* dummy operator callback */
static int pose_constraint_add_exec(bContext *C, wmOperator *op)
{
    Object *ob= object_pose_armature_get(ED_object_active_context(C));
    int type= RNA_enum_get(op->ptr, "type");
    short with_targets= 0;
    
    if (!ob) {
        BKE_report(op->reports, RPT_ERROR, "No active object to add constraint to");
        return OPERATOR_CANCELLED;
    }
        
    /* hack: set constraint targets from selected objects in context is allowed when
     *      operator name included 'with_targets', since the menu doesn't allow multiple properties
     */
    if (strstr(op->idname, "with_targets"))
        with_targets= 1;
    
    return constraint_add_exec(C, op, ob, get_active_constraints(ob), type, with_targets);
}

/* ------------------ */

void OBJECT_OT_constraint_add(wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Add Constraint";
    ot->description = "Add a constraint to the active object";
    ot->idname= "OBJECT_OT_constraint_add";
    
    /* api callbacks */
    ot->invoke= WM_menu_invoke;
    ot->exec= object_constraint_add_exec;
    ot->poll= ED_operator_object_active_editable;
    
    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO;
    
    /* properties */
    ot->prop= RNA_def_enum(ot->srna, "type", constraint_type_items, 0, "Type", "");
}

void OBJECT_OT_constraint_add_with_targets(wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Add Constraint (with Targets)";
    ot->description = "Add a constraint to the active object, with target (where applicable) set to the selected Objects/Bones";
    ot->idname= "OBJECT_OT_constraint_add_with_targets";
    
    /* api callbacks */
    ot->invoke= WM_menu_invoke;
    ot->exec= object_constraint_add_exec;
    ot->poll= ED_operator_object_active_editable;
    
    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO;
    
    /* properties */
    ot->prop= RNA_def_enum(ot->srna, "type", constraint_type_items, 0, "Type", "");
}

void POSE_OT_constraint_add(wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Add Constraint";
    ot->description = "Add a constraint to the active bone";
    ot->idname= "POSE_OT_constraint_add";
    
    /* api callbacks */
    ot->invoke= WM_menu_invoke;
    ot->exec= pose_constraint_add_exec;
    ot->poll= ED_operator_posemode;
    
    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO;
    
    /* properties */
    ot->prop= RNA_def_enum(ot->srna, "type", constraint_type_items, 0, "Type", "");
}

void POSE_OT_constraint_add_with_targets(wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Add Constraint (with Targets)";
    ot->description = "Add a constraint to the active bone, with target (where applicable) set to the selected Objects/Bones";
    ot->idname= "POSE_OT_constraint_add_with_targets";
    
    /* api callbacks */
    ot->invoke= WM_menu_invoke;
    ot->exec= pose_constraint_add_exec;
    ot->poll= ED_operator_posemode;
    
    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO;
    
    /* properties */
    ot->prop= RNA_def_enum(ot->srna, "type", constraint_type_items, 0, "Type", "");
}

/************************ IK Constraint operators *********************/
/* NOTE: only for Pose-Channels */
// TODO: should these be here, or back in editors/armature/poseobject.c again?

/* present menu with options + validation for targets to use */
static int pose_ik_add_invoke(bContext *C, wmOperator *op, wmEvent *UNUSED(evt))
{
    Object *ob= object_pose_armature_get(CTX_data_active_object(C));
    bPoseChannel *pchan= get_active_posechannel(ob);
    bConstraint *con= NULL;
    
    uiPopupMenu *pup;
    uiLayout *layout;
    Object *tar_ob= NULL;
    bPoseChannel *tar_pchan= NULL;
    
    /* must have active bone */
    if (ELEM(NULL, ob, pchan)) {
        BKE_report(op->reports, RPT_ERROR, "Must have active bone to add IK Constraint to");
        return OPERATOR_CANCELLED;
    }
    
    /* bone must not have any constraints already */
    for (con= pchan->constraints.first; con; con= con->next) {
        if (con->type==CONSTRAINT_TYPE_KINEMATIC) break;
    }
    if (con) {
        BKE_report(op->reports, RPT_ERROR, "Bone already has IK Constraint");
        return OPERATOR_CANCELLED;
    }
    
    /* prepare popup menu to choose targetting options */
    pup= uiPupMenuBegin(C, "Add IK", ICON_NONE);
    layout= uiPupMenuLayout(pup);
    
    /* the type of targets we'll set determines the menu entries to show... */
    if (get_new_constraint_target(C, CONSTRAINT_TYPE_KINEMATIC, &tar_ob, &tar_pchan, 0)) {
        /* bone target, or object target? 
         *  - the only thing that matters is that we want a target...
         */
        if (tar_pchan)
            uiItemBooleanO(layout, "To Active Bone", ICON_NONE, "POSE_OT_ik_add", "with_targets", 1);
        else
            uiItemBooleanO(layout, "To Active Object", ICON_NONE, "POSE_OT_ik_add", "with_targets", 1);
    }
    else {
        /* we have a choice of adding to a new empty, or not setting any target (targetless IK) */
        uiItemBooleanO(layout, "To New Empty Object", ICON_NONE, "POSE_OT_ik_add", "with_targets", 1);
        uiItemBooleanO(layout, "Without Targets", ICON_NONE, "POSE_OT_ik_add", "with_targets", 0);
    }
    
    /* finish building the menu, and process it (should result in calling self again) */
    uiPupMenuEnd(C, pup);
    
    return OPERATOR_CANCELLED;
}

/* call constraint_add_exec() to add the IK constraint */
static int pose_ik_add_exec(bContext *C, wmOperator *op)
{
    Object *ob= CTX_data_active_object(C);
    int with_targets= RNA_boolean_get(op->ptr, "with_targets");
    
    /* add the constraint - all necessary checks should have been done by the invoke() callback already... */
    return constraint_add_exec(C, op, ob, get_active_constraints(ob), CONSTRAINT_TYPE_KINEMATIC, with_targets);
}

void POSE_OT_ik_add(wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Add IK to Bone";
    ot->description= "Add IK Constraint to the active Bone";
    ot->idname= "POSE_OT_ik_add";
    
    /* api callbacks */
    ot->invoke= pose_ik_add_invoke;
    ot->exec= pose_ik_add_exec;
    ot->poll= ED_operator_posemode;
    
    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO;
    
    /* properties */
    RNA_def_boolean(ot->srna, "with_targets", 1, "With Targets", "Assign IK Constraint with targets derived from the select bones/objects");
}

/* ------------------ */

/* remove IK constraints from selected bones */
static int pose_ik_clear_exec(bContext *C, wmOperator *UNUSED(op))
{
    Object *ob= object_pose_armature_get(CTX_data_active_object(C));
    
    /* only remove IK Constraints */
    CTX_DATA_BEGIN(C, bPoseChannel*, pchan, selected_pose_bones) 
    {
        bConstraint *con, *next;
        
        // TODO: should we be checking if these contraints were local before we try and remove them?
        for (con= pchan->constraints.first; con; con= next) {
            next= con->next;
            if (con->type==CONSTRAINT_TYPE_KINEMATIC) {
                remove_constraint(&pchan->constraints, con);
            }
        }
        pchan->constflag &= ~(PCHAN_HAS_IK|PCHAN_HAS_TARGET);
    }
    CTX_DATA_END;
    
    /* refresh depsgraph */
    DAG_id_tag_update(&ob->id, OB_RECALC_DATA);

    /* note, notifier might evolve */
    WM_event_add_notifier(C, NC_OBJECT|ND_CONSTRAINT|NA_REMOVED, ob);
    
    return OPERATOR_FINISHED;
}

void POSE_OT_ik_clear(wmOperatorType *ot)
{
    /* identifiers */
    ot->name= "Remove IK";
    ot->description= "Remove all IK Constraints from selected bones";
    ot->idname= "POSE_OT_ik_clear";
    
    /* api callbacks */
    ot->exec= pose_ik_clear_exec;
    ot->poll= ED_operator_posemode;
    
    /* flags */
    ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO;
}