blender/intern/cycles/kernel/kernel_light.h
Brecht Van Lommel c8cbe63947 Cycles: fix issues with texture coordinates and object scale. Auto texture
space size and location were outdated often, and already computed on demand
by blender internal, now do that through RNA as well.
2012-05-08 23:39:31 +00:00

366 lines
9.7 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
typedef struct LightSample {
float3 P;
float3 D;
float3 Ng;
float t;
int object;
int prim;
int shader;
LightType type;
} LightSample;
/* Regular Light */
__device float3 disk_light_sample(float3 v, float randu, float randv)
{
float3 ru, rv;
make_orthonormals(v, &ru, &rv);
to_unit_disk(&randu, &randv);
return ru*randu + rv*randv;
}
__device float3 distant_light_sample(float3 D, float size, float randu, float randv)
{
return normalize(D + disk_light_sample(D, randu, randv)*size);
}
__device float3 sphere_light_sample(float3 P, float3 center, float size, float randu, float randv)
{
return disk_light_sample(normalize(P - center), randu, randv)*size;
}
__device float3 area_light_sample(float3 axisu, float3 axisv, float randu, float randv)
{
randu = randu - 0.5f;
randv = randv - 0.5f;
return axisu*randu + axisv*randv;
}
__device float3 background_light_sample(KernelGlobals *kg, float randu, float randv, float *pdf)
{
/* for the following, the CDF values are actually a pair of floats, with the
function value as X and the actual CDF as Y. The last entry's function
value is the CDF total. */
int res = kernel_data.integrator.pdf_background_res;
int cdf_count = res + 1;
/* this is basically std::lower_bound as used by pbrt */
int first = 0;
int count = res;
while(count > 0) {
int step = count >> 1;
int middle = first + step;
if(kernel_tex_fetch(__light_background_marginal_cdf, middle).y < randv) {
first = middle + 1;
count -= step + 1;
}
else
count = step;
}
int index_v = max(0, first - 1);
kernel_assert(index_v >= 0 && index_v < res);
float2 cdf_v = kernel_tex_fetch(__light_background_marginal_cdf, index_v);
float2 cdf_next_v = kernel_tex_fetch(__light_background_marginal_cdf, index_v + 1);
float2 cdf_last_v = kernel_tex_fetch(__light_background_marginal_cdf, res);
/* importance-sampled V direction */
float dv = (randv - cdf_v.y) / (cdf_next_v.y - cdf_v.y);
float v = (index_v + dv) / res;
/* this is basically std::lower_bound as used by pbrt */
first = 0;
count = res;
while(count > 0) {
int step = count >> 1;
int middle = first + step;
if(kernel_tex_fetch(__light_background_conditional_cdf, index_v * cdf_count + middle).y < randu) {
first = middle + 1;
count -= step + 1;
}
else
count = step;
}
int index_u = max(0, first - 1);
kernel_assert(index_u >= 0 && index_u < res);
float2 cdf_u = kernel_tex_fetch(__light_background_conditional_cdf, index_v * cdf_count + index_u);
float2 cdf_next_u = kernel_tex_fetch(__light_background_conditional_cdf, index_v * cdf_count + index_u + 1);
float2 cdf_last_u = kernel_tex_fetch(__light_background_conditional_cdf, index_v * cdf_count + res);
/* importance-sampled U direction */
float du = (randu - cdf_u.y) / (cdf_next_u.y - cdf_u.y);
float u = (index_u + du) / res;
/* compute pdf */
float denom = cdf_last_u.x * cdf_last_v.x;
float sin_theta = sinf(M_PI_F * v);
if(sin_theta == 0.0f || denom == 0.0f)
*pdf = 0.0f;
else
*pdf = (cdf_u.x * cdf_v.x)/(2.0f * M_PI_F * M_PI_F * sin_theta * denom);
*pdf *= kernel_data.integrator.pdf_lights;
/* compute direction */
return -equirectangular_to_direction(u, v);
}
__device float background_light_pdf(KernelGlobals *kg, float3 direction)
{
float2 uv = direction_to_equirectangular(direction);
int res = kernel_data.integrator.pdf_background_res;
float sin_theta = sinf(uv.y * M_PI_F);
if(sin_theta == 0.0f)
return 0.0f;
int index_u = clamp((int)(uv.x * res), 0, res - 1);
int index_v = clamp((int)(uv.y * res), 0, res - 1);
/* pdfs in V direction */
float2 cdf_last_u = kernel_tex_fetch(__light_background_conditional_cdf, index_v * (res + 1) + res);
float2 cdf_last_v = kernel_tex_fetch(__light_background_marginal_cdf, res);
float denom = cdf_last_u.x * cdf_last_v.x;
if(denom == 0.0f)
return 0.0f;
/* pdfs in U direction */
float2 cdf_u = kernel_tex_fetch(__light_background_conditional_cdf, index_v * (res + 1) + index_u);
float2 cdf_v = kernel_tex_fetch(__light_background_marginal_cdf, index_v);
float pdf = (cdf_u.x * cdf_v.x)/(2.0f * M_PI_F * M_PI_F * sin_theta * denom);
return pdf * kernel_data.integrator.pdf_lights;
}
__device void regular_light_sample(KernelGlobals *kg, int point,
float randu, float randv, float3 P, LightSample *ls, float *pdf)
{
float4 data0 = kernel_tex_fetch(__light_data, point*LIGHT_SIZE + 0);
float4 data1 = kernel_tex_fetch(__light_data, point*LIGHT_SIZE + 1);
LightType type = (LightType)__float_as_int(data0.x);
ls->type = type;
if(type == LIGHT_DISTANT) {
/* distant light */
float3 D = make_float3(data0.y, data0.z, data0.w);
float size = data1.y;
if(size > 0.0f)
D = distant_light_sample(D, size, randu, randv);
ls->P = D;
ls->Ng = D;
ls->D = -D;
ls->t = FLT_MAX;
}
#ifdef __BACKGROUND_MIS__
else if(type == LIGHT_BACKGROUND) {
/* infinite area light (e.g. light dome or env light) */
float3 D = background_light_sample(kg, randu, randv, pdf);
ls->P = D;
ls->Ng = D;
ls->D = -D;
ls->t = FLT_MAX;
}
#endif
else {
ls->P = make_float3(data0.y, data0.z, data0.w);
if(type == LIGHT_POINT) {
float size = data1.y;
/* sphere light */
if(size > 0.0f)
ls->P += sphere_light_sample(P, ls->P, size, randu, randv);
ls->Ng = normalize(P - ls->P);
}
else {
/* area light */
float4 data2 = kernel_tex_fetch(__light_data, point*LIGHT_SIZE + 2);
float4 data3 = kernel_tex_fetch(__light_data, point*LIGHT_SIZE + 3);
float3 axisu = make_float3(data1.y, data1.z, data2.w);
float3 axisv = make_float3(data2.y, data2.z, data2.w);
float3 D = make_float3(data3.y, data3.z, data3.w);
ls->P += area_light_sample(axisu, axisv, randu, randv);
ls->Ng = D;
}
ls->t = 0.0f;
}
ls->shader = __float_as_int(data1.x);
ls->object = ~0;
ls->prim = ~0;
}
__device float regular_light_pdf(KernelGlobals *kg,
const float3 Ng, const float3 I, float t)
{
float pdf = kernel_data.integrator.pdf_lights;
if(t == FLT_MAX)
return pdf;
float cos_pi = dot(Ng, I);
if(cos_pi <= 0.0f)
return 0.0f;
return t*t*pdf/cos_pi;
}
/* Triangle Light */
__device void triangle_light_sample(KernelGlobals *kg, int prim, int object,
float randu, float randv, float time, 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;
ls->t = 0.0f;
ls->type = LIGHT_AREA;
#ifdef __INSTANCING__
/* instance transform */
if(ls->object >= 0) {
Transform tfm = object_fetch_transform(kg, ls->object, time, OBJECT_TRANSFORM);
Transform itfm = object_fetch_transform(kg, ls->object, time, OBJECT_INVERSE_TRANSFORM);
ls->P = transform_point(&tfm, ls->P);
ls->Ng = normalize(transform_direction_transposed(&itfm, 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, float time, float3 P, LightSample *ls, float *pdf)
{
/* 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);
if(prim >= 0) {
int object = __float_as_int(l.w);
triangle_light_sample(kg, prim, object, randu, randv, time, ls);
}
else {
int point = -prim-1;
regular_light_sample(kg, point, randu, randv, P, ls, pdf);
}
/* compute incoming direction and distance */
if(ls->t != FLT_MAX)
ls->D = normalize_len(ls->P - P, &ls->t);
}
__device float light_sample_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 = regular_light_pdf(kg, ls->Ng, I, t);
return pdf;
}
__device void light_select(KernelGlobals *kg, int index, float randu, float randv, float3 P, LightSample *ls, float *pdf)
{
regular_light_sample(kg, index, randu, randv, P, ls, pdf);
}
__device float light_select_pdf(KernelGlobals *kg, LightSample *ls, float3 I, float t)
{
return regular_light_pdf(kg, ls->Ng, I, t);
}
CCL_NAMESPACE_END