forked from bartvdbraak/blender
da376e0237
Cycles uses code from some great open source projects, many thanks them: * BVH building and traversal code from NVidia's "Understanding the Efficiency of Ray Traversal on GPUs": http://code.google.com/p/understanding-the-efficiency-of-ray-traversal-on-gpus/ * Open Shading Language for a large part of the shading system: http://code.google.com/p/openshadinglanguage/ * Blender for procedural textures and a few other nodes. * Approximate Catmull Clark subdivision from NVidia Mesh tools: http://code.google.com/p/nvidia-mesh-tools/ * Sobol direction vectors from: http://web.maths.unsw.edu.au/~fkuo/sobol/ * Film response functions from: http://www.cs.columbia.edu/CAVE/software/softlib/dorf.php
146 lines
3.6 KiB
C++
146 lines
3.6 KiB
C++
/*
|
|
* Copyright 2011, Blender Foundation.
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
CCL_NAMESPACE_BEGIN
|
|
|
|
struct LightSample {
|
|
float3 P;
|
|
float3 Ng;
|
|
int object;
|
|
int prim;
|
|
int shader;
|
|
float weight;
|
|
};
|
|
|
|
/* Point Light */
|
|
|
|
__device void point_light_sample(KernelGlobals *kg, int point,
|
|
float randu, float randv, float3 P, LightSample *ls)
|
|
{
|
|
float4 f = kernel_tex_fetch(__light_point, point);
|
|
|
|
ls->P = make_float3(f.x, f.y, f.z);
|
|
ls->Ng = normalize(ls->P - P);
|
|
ls->shader = __float_as_int(f.w);
|
|
ls->object = ~0;
|
|
ls->prim = ~0;
|
|
}
|
|
|
|
__device float point_light_pdf(KernelGlobals *kg, float t)
|
|
{
|
|
return t*t*kernel_data.integrator.pdf_lights;
|
|
}
|
|
|
|
/* Triangle Light */
|
|
|
|
__device void triangle_light_sample(KernelGlobals *kg, int prim, int object,
|
|
float randu, float randv, LightSample *ls)
|
|
{
|
|
/* triangle, so get position, normal, shader */
|
|
ls->P = triangle_sample_MT(kg, prim, randu, randv);
|
|
ls->Ng = triangle_normal_MT(kg, prim, &ls->shader);
|
|
ls->object = object;
|
|
ls->prim = prim;
|
|
|
|
#ifdef __INSTANCING__
|
|
/* instance transform */
|
|
if(ls->object >= 0) {
|
|
object_position_transform(kg, ls->object, &ls->P);
|
|
object_normal_transform(kg, ls->object, &ls->Ng);
|
|
}
|
|
#endif
|
|
}
|
|
|
|
__device float triangle_light_pdf(KernelGlobals *kg,
|
|
const float3 Ng, const float3 I, float t)
|
|
{
|
|
float cos_pi = fabsf(dot(Ng, I));
|
|
|
|
if(cos_pi == 0.0f)
|
|
return 0.0f;
|
|
|
|
return (t*t*kernel_data.integrator.pdf_triangles)/cos_pi;
|
|
}
|
|
|
|
/* Light Distribution */
|
|
|
|
__device int light_distribution_sample(KernelGlobals *kg, float randt)
|
|
{
|
|
/* this is basically std::upper_bound as used by pbrt, to find a point light or
|
|
triangle to emit from, proportional to area. a good improvement would be to
|
|
also sample proportional to power, though it's not so well defined with
|
|
OSL shaders. */
|
|
int first = 0;
|
|
int len = kernel_data.integrator.num_distribution + 1;
|
|
|
|
while(len > 0) {
|
|
int half_len = len >> 1;
|
|
int middle = first + half_len;
|
|
|
|
if(randt < kernel_tex_fetch(__light_distribution, middle).x) {
|
|
len = half_len;
|
|
}
|
|
else {
|
|
first = middle + 1;
|
|
len = len - half_len - 1;
|
|
}
|
|
}
|
|
|
|
first = max(0, first-1);
|
|
kernel_assert(first >= 0 && first < kernel_data.integrator.num_distribution);
|
|
|
|
return first;
|
|
}
|
|
|
|
/* Generic Light */
|
|
|
|
__device void light_sample(KernelGlobals *kg, float randt, float randu, float randv, float3 P, LightSample *ls)
|
|
{
|
|
/* sample index */
|
|
int index = light_distribution_sample(kg, randt);
|
|
|
|
/* fetch light data */
|
|
float4 l = kernel_tex_fetch(__light_distribution, index);
|
|
int prim = __float_as_int(l.y);
|
|
ls->weight = l.z;
|
|
|
|
if(prim >= 0) {
|
|
int object = __float_as_int(l.w);
|
|
triangle_light_sample(kg, prim, object, randu, randv, ls);
|
|
}
|
|
else {
|
|
int point = -prim-1;
|
|
point_light_sample(kg, point, randu, randv, P, ls);
|
|
}
|
|
}
|
|
|
|
__device float light_pdf(KernelGlobals *kg, LightSample *ls, float3 I, float t)
|
|
{
|
|
float pdf;
|
|
|
|
if(ls->prim != ~0)
|
|
pdf = triangle_light_pdf(kg, ls->Ng, I, t);
|
|
else
|
|
pdf = point_light_pdf(kg, t);
|
|
|
|
return pdf;
|
|
}
|
|
|
|
CCL_NAMESPACE_END
|
|
|