Blender V2.61 - r43446

kernel_light.h

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00001 /*
00002  * Copyright 2011, Blender Foundation.
00003  *
00004  * This program is free software; you can redistribute it and/or
00005  * modify it under the terms of the GNU General Public License
00006  * as published by the Free Software Foundation; either version 2
00007  * of the License, or (at your option) any later version.
00008  *
00009  * This program is distributed in the hope that it will be useful,
00010  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00011  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00012  * GNU General Public License for more details.
00013  *
00014  * You should have received a copy of the GNU General Public License
00015  * along with this program; if not, write to the Free Software Foundation,
00016  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
00017  */
00018 
00019 CCL_NAMESPACE_BEGIN
00020 
00021 typedef struct LightSample {
00022     float3 P;
00023     float3 D;
00024     float3 Ng;
00025     float t;
00026     int object;
00027     int prim;
00028     int shader;
00029 } LightSample;
00030 
00031 /* Regular Light */
00032 
00033 __device float3 disk_light_sample(float3 v, float randu, float randv)
00034 {
00035     float3 ru, rv;
00036 
00037     make_orthonormals(v, &ru, &rv);
00038     to_unit_disk(&randu, &randv);
00039 
00040     return ru*randu + rv*randv;
00041 }
00042 
00043 __device float3 distant_light_sample(float3 D, float size, float randu, float randv)
00044 {
00045     return normalize(D + disk_light_sample(D, randu, randv)*size);
00046 }
00047 
00048 __device float3 sphere_light_sample(float3 P, float3 center, float size, float randu, float randv)
00049 {
00050     return disk_light_sample(normalize(P - center), randu, randv)*size;
00051 }
00052 
00053 __device float3 area_light_sample(float3 axisu, float3 axisv, float randu, float randv)
00054 {
00055     randu = randu - 0.5f;
00056     randv = randv - 0.5f;
00057 
00058     return axisu*randu + axisv*randv;
00059 }
00060 
00061 __device void regular_light_sample(KernelGlobals *kg, int point,
00062     float randu, float randv, float3 P, LightSample *ls)
00063 {
00064     float4 data0 = kernel_tex_fetch(__light_data, point*LIGHT_SIZE + 0);
00065     float4 data1 = kernel_tex_fetch(__light_data, point*LIGHT_SIZE + 1);
00066 
00067     LightType type = (LightType)__float_as_int(data0.x);
00068 
00069     if(type == LIGHT_DISTANT) {
00070         /* distant light */
00071         float3 D = make_float3(data0.y, data0.z, data0.w);
00072         float size = data1.y;
00073 
00074         if(size > 0.0f)
00075             D = distant_light_sample(D, size, randu, randv);
00076 
00077         ls->P = D;
00078         ls->Ng = D;
00079         ls->D = -D;
00080         ls->t = FLT_MAX;
00081     }
00082     else {
00083         ls->P = make_float3(data0.y, data0.z, data0.w);
00084 
00085         if(type == LIGHT_POINT) {
00086             float size = data1.y;
00087 
00088             /* sphere light */
00089             if(size > 0.0f)
00090                 ls->P += sphere_light_sample(P, ls->P, size, randu, randv);
00091 
00092             ls->Ng = normalize(P - ls->P);
00093         }
00094         else {
00095             /* area light */
00096             float4 data2 = kernel_tex_fetch(__light_data, point*LIGHT_SIZE + 2);
00097             float4 data3 = kernel_tex_fetch(__light_data, point*LIGHT_SIZE + 3);
00098 
00099             float3 axisu = make_float3(data1.y, data1.z, data2.w);
00100             float3 axisv = make_float3(data2.y, data2.z, data2.w);
00101             float3 D = make_float3(data3.y, data3.z, data3.w);
00102 
00103             ls->P += area_light_sample(axisu, axisv, randu, randv);
00104             ls->Ng = D;
00105         }
00106 
00107         ls->t = 0.0f;
00108     }
00109 
00110     ls->shader = __float_as_int(data1.x);
00111     ls->object = ~0;
00112     ls->prim = ~0;
00113 }
00114 
00115 __device float regular_light_pdf(KernelGlobals *kg,
00116     const float3 Ng, const float3 I, float t)
00117 {
00118     float pdf = kernel_data.integrator.pdf_lights;
00119 
00120     if(t == FLT_MAX)
00121         return pdf;
00122 
00123     float cos_pi = dot(Ng, I);
00124 
00125     if(cos_pi <= 0.0f)
00126         return 0.0f;
00127 
00128     return t*t*pdf/cos_pi;
00129 }
00130 
00131 /* Triangle Light */
00132 
00133 __device void triangle_light_sample(KernelGlobals *kg, int prim, int object,
00134     float randu, float randv, LightSample *ls)
00135 {
00136     /* triangle, so get position, normal, shader */
00137     ls->P = triangle_sample_MT(kg, prim, randu, randv);
00138     ls->Ng = triangle_normal_MT(kg, prim, &ls->shader);
00139     ls->object = object;
00140     ls->prim = prim;
00141     ls->t = 0.0f;
00142 
00143 #ifdef __INSTANCING__
00144     /* instance transform */
00145     if(ls->object >= 0) {
00146         object_position_transform(kg, ls->object, &ls->P);
00147         object_normal_transform(kg, ls->object, &ls->Ng);
00148     }
00149 #endif
00150 }
00151 
00152 __device float triangle_light_pdf(KernelGlobals *kg,
00153     const float3 Ng, const float3 I, float t)
00154 {
00155     float cos_pi = fabsf(dot(Ng, I));
00156 
00157     if(cos_pi == 0.0f)
00158         return 0.0f;
00159     
00160     return (t*t*kernel_data.integrator.pdf_triangles)/cos_pi;
00161 }
00162 
00163 /* Light Distribution */
00164 
00165 __device int light_distribution_sample(KernelGlobals *kg, float randt)
00166 {
00167     /* this is basically std::upper_bound as used by pbrt, to find a point light or
00168        triangle to emit from, proportional to area. a good improvement would be to
00169        also sample proportional to power, though it's not so well defined with
00170        OSL shaders. */
00171     int first = 0;
00172     int len = kernel_data.integrator.num_distribution + 1;
00173 
00174     while(len > 0) {
00175         int half_len = len >> 1;
00176         int middle = first + half_len;
00177 
00178         if(randt < kernel_tex_fetch(__light_distribution, middle).x) {
00179             len = half_len;
00180         }
00181         else {
00182             first = middle + 1;
00183             len = len - half_len - 1;
00184         }
00185     }
00186 
00187     first = max(0, first-1);
00188     kernel_assert(first >= 0 && first < kernel_data.integrator.num_distribution);
00189 
00190     return first;
00191 }
00192 
00193 /* Generic Light */
00194 
00195 __device void light_sample(KernelGlobals *kg, float randt, float randu, float randv, float3 P, LightSample *ls)
00196 {
00197     /* sample index */
00198     int index = light_distribution_sample(kg, randt);
00199 
00200     /* fetch light data */
00201     float4 l = kernel_tex_fetch(__light_distribution, index);
00202     int prim = __float_as_int(l.y);
00203 
00204     if(prim >= 0) {
00205         int object = __float_as_int(l.w);
00206         triangle_light_sample(kg, prim, object, randu, randv, ls);
00207     }
00208     else {
00209         int point = -prim-1;
00210         regular_light_sample(kg, point, randu, randv, P, ls);
00211     }
00212 
00213     /* compute incoming direction and distance */
00214     if(ls->t != FLT_MAX)
00215         ls->D = normalize_len(ls->P - P, &ls->t);
00216 }
00217 
00218 __device float light_sample_pdf(KernelGlobals *kg, LightSample *ls, float3 I, float t)
00219 {
00220     float pdf;
00221 
00222     if(ls->prim != ~0)
00223         pdf = triangle_light_pdf(kg, ls->Ng, I, t);
00224     else
00225         pdf = regular_light_pdf(kg, ls->Ng, I, t);
00226     
00227     return pdf;
00228 }
00229 
00230 __device void light_select(KernelGlobals *kg, int index, float randu, float randv, float3 P, LightSample *ls)
00231 {
00232     regular_light_sample(kg, index, randu, randv, P, ls);
00233 }
00234 
00235 __device float light_select_pdf(KernelGlobals *kg, LightSample *ls, float3 I, float t)
00236 {
00237     return regular_light_pdf(kg, ls->Ng, I, t);
00238 }
00239 
00240 CCL_NAMESPACE_END
00241