jitter.c

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/*
 * Jitter offset table
 *
 *
 * ***** 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): none yet.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

#include <math.h>
#include <string.h>
#include "MEM_guardedalloc.h"

#include "BLI_rand.h"
#include "BLI_jitter.h"


void BLI_jitterate1(float *jit1, float *jit2, int num, float rad1)
{
    int i , j , k;
    float vecx, vecy, dvecx, dvecy, x, y, len;

    for (i = 2*num-2; i>=0 ; i-=2) {
        dvecx = dvecy = 0.0;
        x = jit1[i];
        y = jit1[i+1];
        for (j = 2*num-2; j>=0 ; j-=2) {
            if (i != j){
                vecx = jit1[j] - x - 1.0f;
                vecy = jit1[j+1] - y - 1.0f;
                for (k = 3; k>0 ; k--){
                    if( fabsf(vecx)<rad1 && fabsf(vecy)<rad1) {
                        len=  sqrt(vecx*vecx + vecy*vecy);
                        if(len>0 && len<rad1) {
                            len= len/rad1;
                            dvecx += vecx/len;
                            dvecy += vecy/len;
                        }
                    }
                    vecx += 1.0f;

                    if( fabsf(vecx)<rad1 && fabsf(vecy)<rad1) {
                        len=  sqrt(vecx*vecx + vecy*vecy);
                        if(len>0 && len<rad1) {
                            len= len/rad1;
                            dvecx += vecx/len;
                            dvecy += vecy/len;
                        }
                    }
                    vecx += 1.0f;

                    if( fabsf(vecx)<rad1 && fabsf(vecy)<rad1) {
                        len=  sqrt(vecx*vecx + vecy*vecy);
                        if(len>0 && len<rad1) {
                            len= len/rad1;
                            dvecx += vecx/len;
                            dvecy += vecy/len;
                        }
                    }
                    vecx -= 2.0f;
                    vecy += 1.0f;
                }
            }
        }

        x -= dvecx/18.0f;
        y -= dvecy/18.0f;
        x -= floorf(x) ;
        y -= floorf(y);
        jit2[i] = x;
        jit2[i+1] = y;
    }
    memcpy(jit1,jit2,2 * num * sizeof(float));
}

void BLI_jitterate2(float *jit1, float *jit2, int num, float rad2)
{
    int i, j;
    float vecx, vecy, dvecx, dvecy, x, y;

    for (i=2*num -2; i>= 0 ; i-=2){
        dvecx = dvecy = 0.0;
        x = jit1[i];
        y = jit1[i+1];
        for (j =2*num -2; j>= 0 ; j-=2){
            if (i != j){
                vecx = jit1[j] - x - 1.0f;
                vecy = jit1[j+1] - y - 1.0f;

                if( fabsf(vecx)<rad2) dvecx+= vecx*rad2;
                vecx += 1.0f;
                if( fabsf(vecx)<rad2) dvecx+= vecx*rad2;
                vecx += 1.0f;
                if( fabsf(vecx)<rad2) dvecx+= vecx*rad2;

                if( fabsf(vecy)<rad2) dvecy+= vecy*rad2;
                vecy += 1.0f;
                if( fabsf(vecy)<rad2) dvecy+= vecy*rad2;
                vecy += 1.0f;
                if( fabsf(vecy)<rad2) dvecy+= vecy*rad2;

            }
        }

        x -= dvecx/2.0f;
        y -= dvecy/2.0f;
        x -= floorf(x) ;
        y -= floorf(y);
        jit2[i] = x;
        jit2[i+1] = y;
    }
    memcpy(jit1,jit2,2 * num * sizeof(float));
}


void BLI_initjit(float *jitarr, int num)
{
    float *jit2, x, rad1, rad2, rad3;
    int i;

    if(num==0) return;

    jit2= MEM_mallocN(12 + 2*sizeof(float)*num, "initjit");
    rad1= 1.0f/sqrtf((float)num);
    rad2= 1.0f/((float)num);
    rad3= sqrtf((float)num)/((float)num);

    BLI_srand(31415926 + num);
    x= 0;
    for(i=0; i<2*num; i+=2) {
        jitarr[i]= x+ rad1*(float)(0.5-BLI_drand());
        jitarr[i+1]= ((float)i/2)/num +rad1*(float)(0.5-BLI_drand());
        x+= rad3;
        x -= floorf(x);
    }

    for (i=0 ; i<24 ; i++) {
        BLI_jitterate1(jitarr, jit2, num, rad1);
        BLI_jitterate1(jitarr, jit2, num, rad1);
        BLI_jitterate2(jitarr, jit2, num, rad2);
    }

    MEM_freeN(jit2);
    
    /* finally, move jittertab to be centered around (0,0) */
    for(i=0; i<2*num; i+=2) {
        jitarr[i] -= 0.5f;
        jitarr[i+1] -= 0.5f;
    }
    
}


/* eof */