blender/intern/cycles/kernel/kernel_montecarlo.h
Ton Roosendaal da376e0237 Cycles render engine, initial commit. This is the engine itself, blender modifications and build instructions will follow later.
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
2011-04-27 11:58:34 +00:00

197 lines
5.2 KiB
C

/*
* Parts adapted from Open Shading Language with this license:
*
* Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
* All Rights Reserved.
*
* Modifications Copyright 2011, Blender Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Sony Pictures Imageworks nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef __KERNEL_MONTECARLO_CL__
#define __KERNEL_MONTECARLO_CL__
CCL_NAMESPACE_BEGIN
/// Given values x and y on [0,1], convert them in place to values on
/// [-1,1] uniformly distributed over a unit sphere. This code is
/// derived from Peter Shirley, "Realistic Ray Tracing", p. 103.
__device void to_unit_disk(float *x, float *y)
{
float r, phi;
float a = 2.0f * (*x) - 1.0f;
float b = 2.0f * (*y) - 1.0f;
if(a > -b) {
if(a > b) {
r = a;
phi = M_PI_4_F *(b/a);
} else {
r = b;
phi = M_PI_4_F *(2.0f - a/b);
}
} else {
if(a < b) {
r = -a;
phi = M_PI_4_F *(4.0f + b/a);
} else {
r = -b;
if(b != 0.0f)
phi = M_PI_4_F *(6.0f - a/b);
else
phi = 0.0f;
}
}
*x = r * cosf(phi);
*y = r * sinf(phi);
}
__device_inline void make_orthonormals(const float3 N, float3 *a, float3 *b)
{
if(N.x != N.y || N.x != N.z)
*a = make_float3(N.z-N.y, N.x-N.z, N.y-N.x); //(1,1,1)x N
else
*a = make_float3(N.z-N.y, N.x+N.z, -N.y-N.x); //(-1,1,1)x N
*a = normalize(*a);
*b = cross(N, *a);
}
__device void make_orthonormals_tangent(const float3 N, const float3 T, float3 *a, float3 *b)
{
*b = cross(N, T);
*a = cross(*b, N);
}
__device_inline void sample_cos_hemisphere(const float3 N,
float randu, float randv, float3 *omega_in, float *pdf)
{
// Default closure BSDF implementation: uniformly sample
// cosine-weighted hemisphere above the point.
to_unit_disk(&randu, &randv);
float costheta = sqrtf(max(1.0f - randu * randu - randv * randv, 0.0f));
float3 T, B;
make_orthonormals(N, &T, &B);
*omega_in = randu * T + randv * B + costheta * N;
*pdf = costheta *M_1_PI_F;
}
__device_inline void sample_uniform_hemisphere(const float3 N,
float randu, float randv,
float3 *omega_in, float *pdf)
{
float z = randu;
float r = sqrtf(max(0.f, 1.f - z*z));
float phi = 2.f * M_PI_F * randv;
float x = r * cosf(phi);
float y = r * sinf(phi);
float3 T, B;
make_orthonormals (N, &T, &B);
*omega_in = x * T + y * B + z * N;
*pdf = 0.5f * M_1_PI_F;
}
__device float3 sample_uniform_sphere(float u1, float u2)
{
float z = 1.0f - 2.0f*u1;
float r = sqrtf(fmaxf(0.0f, 1.0f - z*z));
float phi = 2.0f*M_PI_F*u2;
float x = r*cosf(phi);
float y = r*sinf(phi);
return make_float3(x, y, z);
}
__device float power_heuristic(float a, float b)
{
return (a*a)/(a*a + b*b);
}
__device float2 concentric_sample_disk(float u1, float u2)
{
float r, theta;
// Map uniform random numbers to $[-1,1]^2$
float sx = 2 * u1 - 1;
float sy = 2 * u2 - 1;
// Map square to $(r,\theta)$
// Handle degeneracy at the origin
if(sx == 0.0f && sy == 0.0f) {
return make_float2(0.0f, 0.0f);
}
if(sx >= -sy) {
if(sx > sy) {
// Handle first region of disk
r = sx;
if(sy > 0.0f) theta = sy/r;
else theta = 8.0f + sy/r;
}
else {
// Handle second region of disk
r = sy;
theta = 2.0f - sx/r;
}
}
else {
if(sx <= sy) {
// Handle third region of disk
r = -sx;
theta = 4.0f - sy/r;
}
else {
// Handle fourth region of disk
r = -sy;
theta = 6.0f + sx/r;
}
}
theta *= M_PI_4_F;
return make_float2(r * cosf(theta), r * sinf(theta));
}
/* Spherical coordinates <-> Cartesion direction */
__device float2 direction_to_spherical(float3 dir)
{
float theta = acosf(dir.z);
float phi = atan2f(dir.x, dir.y);
return make_float2(theta, phi);
}
__device float3 spherical_to_direction(float theta, float phi)
{
return make_float3(
sinf(theta)*cosf(phi),
sinf(theta)*sinf(phi),
cosf(theta));
}
CCL_NAMESPACE_END
#endif /* __KERNEL_MONTECARLO_CL__ */