forked from bartvdbraak/blender
1161 lines
35 KiB
C++
1161 lines
35 KiB
C++
/*
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* Copyright 2011-2013 Blender Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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CCL_NAMESPACE_BEGIN
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/* Light Sample result */
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typedef struct LightSample {
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float3 P; /* position on light, or direction for distant light */
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float3 Ng; /* normal on light */
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float3 D; /* direction from shading point to light */
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float t; /* distance to light (FLT_MAX for distant light) */
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float u, v; /* parametric coordinate on primitive */
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float pdf; /* light sampling probability density function */
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float eval_fac; /* intensity multiplier */
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int object; /* object id for triangle/curve lights */
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int prim; /* primitive id for triangle/curve lights */
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int shader; /* shader id */
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int lamp; /* lamp id */
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LightType type; /* type of light */
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} LightSample;
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/* Area light sampling */
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/* Uses the following paper:
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*
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* Carlos Urena et al.
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* An Area-Preserving Parametrization for Spherical Rectangles.
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*
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* https://www.solidangle.com/research/egsr2013_spherical_rectangle.pdf
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*
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* Note: light_p is modified when sample_coord is true.
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*/
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ccl_device_inline float rect_light_sample(float3 P,
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float3 *light_p,
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float3 axisu, float3 axisv,
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float randu, float randv,
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bool sample_coord)
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{
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/* In our name system we're using P for the center,
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* which is o in the paper.
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*/
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float3 corner = *light_p - axisu * 0.5f - axisv * 0.5f;
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float axisu_len, axisv_len;
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/* Compute local reference system R. */
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float3 x = normalize_len(axisu, &axisu_len);
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float3 y = normalize_len(axisv, &axisv_len);
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float3 z = cross(x, y);
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/* Compute rectangle coords in local reference system. */
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float3 dir = corner - P;
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float z0 = dot(dir, z);
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/* Flip 'z' to make it point against Q. */
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if(z0 > 0.0f) {
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z *= -1.0f;
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z0 *= -1.0f;
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}
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float x0 = dot(dir, x);
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float y0 = dot(dir, y);
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float x1 = x0 + axisu_len;
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float y1 = y0 + axisv_len;
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/* Compute internal angles (gamma_i). */
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float4 diff = make_float4(x0, y1, x1, y0) - make_float4(x1, y0, x0, y1);
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float4 nz = make_float4(y0, x1, y1, x0) * diff;
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nz = nz / sqrt(z0 * z0 * diff * diff + nz * nz);
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float g0 = safe_acosf(-nz.x * nz.y);
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float g1 = safe_acosf(-nz.y * nz.z);
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float g2 = safe_acosf(-nz.z * nz.w);
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float g3 = safe_acosf(-nz.w * nz.x);
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/* Compute predefined constants. */
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float b0 = nz.x;
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float b1 = nz.z;
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float b0sq = b0 * b0;
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float k = M_2PI_F - g2 - g3;
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/* Compute solid angle from internal angles. */
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float S = g0 + g1 - k;
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if(sample_coord) {
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/* Compute cu. */
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float au = randu * S + k;
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float fu = (cosf(au) * b0 - b1) / sinf(au);
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float cu = 1.0f / sqrtf(fu * fu + b0sq) * (fu > 0.0f ? 1.0f : -1.0f);
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cu = clamp(cu, -1.0f, 1.0f);
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/* Compute xu. */
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float xu = -(cu * z0) / max(sqrtf(1.0f - cu * cu), 1e-7f);
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xu = clamp(xu, x0, x1);
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/* Compute yv. */
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float z0sq = z0 * z0;
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float y0sq = y0 * y0;
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float y1sq = y1 * y1;
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float d = sqrtf(xu * xu + z0sq);
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float h0 = y0 / sqrtf(d * d + y0sq);
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float h1 = y1 / sqrtf(d * d + y1sq);
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float hv = h0 + randv * (h1 - h0), hv2 = hv * hv;
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float yv = (hv2 < 1.0f - 1e-6f) ? (hv * d) / sqrtf(1.0f - hv2) : y1;
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/* Transform (xu, yv, z0) to world coords. */
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*light_p = P + xu * x + yv * y + z0 * z;
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}
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/* return pdf */
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if(S != 0.0f)
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return 1.0f / S;
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else
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return 0.0f;
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}
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ccl_device_inline float3 ellipse_sample(float3 ru, float3 rv, float randu, float randv)
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{
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to_unit_disk(&randu, &randv);
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return ru*randu + rv*randv;
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}
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ccl_device float3 disk_light_sample(float3 v, float randu, float randv)
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{
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float3 ru, rv;
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make_orthonormals(v, &ru, &rv);
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return ellipse_sample(ru, rv, randu, randv);
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}
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ccl_device float3 distant_light_sample(float3 D, float radius, float randu, float randv)
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{
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return normalize(D + disk_light_sample(D, randu, randv)*radius);
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}
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ccl_device float3 sphere_light_sample(float3 P, float3 center, float radius, float randu, float randv)
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{
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return disk_light_sample(normalize(P - center), randu, randv)*radius;
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}
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ccl_device float spot_light_attenuation(float3 dir, float spot_angle, float spot_smooth, LightSample *ls)
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{
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float3 I = ls->Ng;
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float attenuation = dot(dir, I);
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if(attenuation <= spot_angle) {
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attenuation = 0.0f;
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}
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else {
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float t = attenuation - spot_angle;
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if(t < spot_smooth && spot_smooth != 0.0f)
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attenuation *= smoothstepf(t/spot_smooth);
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}
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return attenuation;
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}
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ccl_device float lamp_light_pdf(KernelGlobals *kg, const float3 Ng, const float3 I, float t)
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{
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float cos_pi = dot(Ng, I);
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if(cos_pi <= 0.0f)
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return 0.0f;
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return t*t/cos_pi;
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}
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/* Background Light */
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#ifdef __BACKGROUND_MIS__
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/* TODO(sergey): In theory it should be all fine to use noinline for all
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* devices, but we're so close to the release so better not screw things
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* up for CPU at least.
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*/
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#ifdef __KERNEL_GPU__
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ccl_device_noinline
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#else
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ccl_device
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#endif
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float3 background_map_sample(KernelGlobals *kg, float randu, float randv, float *pdf)
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{
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/* for the following, the CDF values are actually a pair of floats, with the
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* function value as X and the actual CDF as Y. The last entry's function
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* value is the CDF total. */
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int res_x = kernel_data.integrator.pdf_background_res_x;
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int res_y = kernel_data.integrator.pdf_background_res_y;
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int cdf_width = res_x + 1;
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/* this is basically std::lower_bound as used by pbrt */
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int first = 0;
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int count = res_y;
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while(count > 0) {
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int step = count >> 1;
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int middle = first + step;
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if(kernel_tex_fetch(__light_background_marginal_cdf, middle).y < randv) {
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first = middle + 1;
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count -= step + 1;
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}
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else
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count = step;
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}
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int index_v = max(0, first - 1);
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kernel_assert(index_v >= 0 && index_v < res_y);
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float2 cdf_v = kernel_tex_fetch(__light_background_marginal_cdf, index_v);
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float2 cdf_next_v = kernel_tex_fetch(__light_background_marginal_cdf, index_v + 1);
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float2 cdf_last_v = kernel_tex_fetch(__light_background_marginal_cdf, res_y);
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/* importance-sampled V direction */
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float dv = inverse_lerp(cdf_v.y, cdf_next_v.y, randv);
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float v = (index_v + dv) / res_y;
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/* this is basically std::lower_bound as used by pbrt */
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first = 0;
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count = res_x;
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while(count > 0) {
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int step = count >> 1;
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int middle = first + step;
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if(kernel_tex_fetch(__light_background_conditional_cdf, index_v * cdf_width + middle).y < randu) {
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first = middle + 1;
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count -= step + 1;
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}
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else
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count = step;
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}
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int index_u = max(0, first - 1);
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kernel_assert(index_u >= 0 && index_u < res_x);
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float2 cdf_u = kernel_tex_fetch(__light_background_conditional_cdf, index_v * cdf_width + index_u);
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float2 cdf_next_u = kernel_tex_fetch(__light_background_conditional_cdf, index_v * cdf_width + index_u + 1);
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float2 cdf_last_u = kernel_tex_fetch(__light_background_conditional_cdf, index_v * cdf_width + res_x);
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/* importance-sampled U direction */
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float du = inverse_lerp(cdf_u.y, cdf_next_u.y, randu);
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float u = (index_u + du) / res_x;
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/* compute pdf */
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float denom = cdf_last_u.x * cdf_last_v.x;
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float sin_theta = sinf(M_PI_F * v);
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if(sin_theta == 0.0f || denom == 0.0f)
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*pdf = 0.0f;
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else
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*pdf = (cdf_u.x * cdf_v.x)/(M_2PI_F * M_PI_F * sin_theta * denom);
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/* compute direction */
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return equirectangular_to_direction(u, v);
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}
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/* TODO(sergey): Same as above, after the release we should consider using
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* 'noinline' for all devices.
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*/
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#ifdef __KERNEL_GPU__
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ccl_device_noinline
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#else
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ccl_device
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#endif
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float background_map_pdf(KernelGlobals *kg, float3 direction)
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{
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float2 uv = direction_to_equirectangular(direction);
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int res_x = kernel_data.integrator.pdf_background_res_x;
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int res_y = kernel_data.integrator.pdf_background_res_y;
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int cdf_width = res_x + 1;
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float sin_theta = sinf(uv.y * M_PI_F);
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if(sin_theta == 0.0f)
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return 0.0f;
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int index_u = clamp(float_to_int(uv.x * res_x), 0, res_x - 1);
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int index_v = clamp(float_to_int(uv.y * res_y), 0, res_y - 1);
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/* pdfs in V direction */
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float2 cdf_last_u = kernel_tex_fetch(__light_background_conditional_cdf, index_v * cdf_width + res_x);
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float2 cdf_last_v = kernel_tex_fetch(__light_background_marginal_cdf, res_y);
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float denom = cdf_last_u.x * cdf_last_v.x;
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if(denom == 0.0f)
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return 0.0f;
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/* pdfs in U direction */
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float2 cdf_u = kernel_tex_fetch(__light_background_conditional_cdf, index_v * cdf_width + index_u);
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float2 cdf_v = kernel_tex_fetch(__light_background_marginal_cdf, index_v);
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return (cdf_u.x * cdf_v.x)/(M_2PI_F * M_PI_F * sin_theta * denom);
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}
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ccl_device_inline bool background_portal_data_fetch_and_check_side(KernelGlobals *kg,
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float3 P,
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int index,
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float3 *lightpos,
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float3 *dir)
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{
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int portal = kernel_data.integrator.portal_offset + index;
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const ccl_global KernelLight *klight = &kernel_tex_fetch(__lights, portal);
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*lightpos = make_float3(klight->co[0], klight->co[1], klight->co[2]);
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*dir = make_float3(klight->area.dir[0], klight->area.dir[1], klight->area.dir[2]);
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/* Check whether portal is on the right side. */
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if(dot(*dir, P - *lightpos) > 1e-4f)
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return true;
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return false;
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}
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ccl_device_inline float background_portal_pdf(KernelGlobals *kg,
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float3 P,
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float3 direction,
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int ignore_portal,
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bool *is_possible)
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{
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float portal_pdf = 0.0f;
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int num_possible = 0;
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for(int p = 0; p < kernel_data.integrator.num_portals; p++) {
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if(p == ignore_portal)
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continue;
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float3 lightpos, dir;
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if(!background_portal_data_fetch_and_check_side(kg, P, p, &lightpos, &dir))
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continue;
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/* There's a portal that could be sampled from this position. */
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if(is_possible) {
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*is_possible = true;
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}
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num_possible++;
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int portal = kernel_data.integrator.portal_offset + p;
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const ccl_global KernelLight *klight = &kernel_tex_fetch(__lights, portal);
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float3 axisu = make_float3(klight->area.axisu[0], klight->area.axisu[1], klight->area.axisu[2]);
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float3 axisv = make_float3(klight->area.axisv[0], klight->area.axisv[1], klight->area.axisv[2]);
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bool is_round = (klight->area.invarea < 0.0f);
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if(!ray_quad_intersect(P, direction, 1e-4f, FLT_MAX, lightpos, axisu, axisv, dir, NULL, NULL, NULL, NULL, is_round))
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continue;
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if(is_round) {
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float t;
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float3 D = normalize_len(lightpos - P, &t);
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portal_pdf += fabsf(klight->area.invarea) * lamp_light_pdf(kg, dir, -D, t);
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}
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else {
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portal_pdf += rect_light_sample(P, &lightpos, axisu, axisv, 0.0f, 0.0f, false);
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}
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}
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if(ignore_portal >= 0) {
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/* We have skipped a portal that could be sampled as well. */
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num_possible++;
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}
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return (num_possible > 0)? portal_pdf / num_possible: 0.0f;
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}
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ccl_device int background_num_possible_portals(KernelGlobals *kg, float3 P)
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{
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int num_possible_portals = 0;
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for(int p = 0; p < kernel_data.integrator.num_portals; p++) {
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float3 lightpos, dir;
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if(background_portal_data_fetch_and_check_side(kg, P, p, &lightpos, &dir))
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num_possible_portals++;
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}
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return num_possible_portals;
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}
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ccl_device float3 background_portal_sample(KernelGlobals *kg,
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float3 P,
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float randu,
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float randv,
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int num_possible,
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int *sampled_portal,
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float *pdf)
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{
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/* Pick a portal, then re-normalize randv. */
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randv *= num_possible;
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int portal = (int)randv;
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randv -= portal;
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/* TODO(sergey): Some smarter way of finding portal to sample
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* is welcome.
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*/
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for(int p = 0; p < kernel_data.integrator.num_portals; p++) {
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/* Search for the sampled portal. */
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float3 lightpos, dir;
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if(!background_portal_data_fetch_and_check_side(kg, P, p, &lightpos, &dir))
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continue;
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if(portal == 0) {
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/* p is the portal to be sampled. */
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int portal = kernel_data.integrator.portal_offset + p;
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const ccl_global KernelLight *klight = &kernel_tex_fetch(__lights, portal);
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float3 axisu = make_float3(klight->area.axisu[0], klight->area.axisu[1], klight->area.axisu[2]);
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float3 axisv = make_float3(klight->area.axisv[0], klight->area.axisv[1], klight->area.axisv[2]);
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bool is_round = (klight->area.invarea < 0.0f);
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float3 D;
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if(is_round) {
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lightpos += ellipse_sample(axisu*0.5f, axisv*0.5f, randu, randv);
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float t;
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D = normalize_len(lightpos - P, &t);
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*pdf = fabsf(klight->area.invarea) * lamp_light_pdf(kg, dir, -D, t);
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}
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else {
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*pdf = rect_light_sample(P, &lightpos,
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axisu, axisv,
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randu, randv,
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true);
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D = normalize(lightpos - P);
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}
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*pdf /= num_possible;
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*sampled_portal = p;
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return D;
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}
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portal--;
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}
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return make_float3(0.0f, 0.0f, 0.0f);
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}
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ccl_device_inline float3 background_light_sample(KernelGlobals *kg,
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float3 P,
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float randu, float randv,
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float *pdf)
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{
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/* Probability of sampling portals instead of the map. */
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float portal_sampling_pdf = kernel_data.integrator.portal_pdf;
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/* Check if there are portals in the scene which we can sample. */
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if(portal_sampling_pdf > 0.0f) {
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int num_portals = background_num_possible_portals(kg, P);
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if(num_portals > 0) {
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if(portal_sampling_pdf == 1.0f || randu < portal_sampling_pdf) {
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if(portal_sampling_pdf < 1.0f) {
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randu /= portal_sampling_pdf;
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}
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int portal;
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float3 D = background_portal_sample(kg, P, randu, randv, num_portals, &portal, pdf);
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if(num_portals > 1) {
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/* Ignore the chosen portal, its pdf is already included. */
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*pdf += background_portal_pdf(kg, P, D, portal, NULL);
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}
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/* We could also have sampled the map, so combine with MIS. */
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if(portal_sampling_pdf < 1.0f) {
|
|
float cdf_pdf = background_map_pdf(kg, D);
|
|
*pdf = (portal_sampling_pdf * (*pdf)
|
|
+ (1.0f - portal_sampling_pdf) * cdf_pdf);
|
|
}
|
|
return D;
|
|
}
|
|
else {
|
|
/* Sample map, but with nonzero portal_sampling_pdf for MIS. */
|
|
randu = (randu - portal_sampling_pdf) / (1.0f - portal_sampling_pdf);
|
|
}
|
|
}
|
|
else {
|
|
/* We can't sample a portal.
|
|
* Check if we can sample the map instead.
|
|
*/
|
|
if(portal_sampling_pdf == 1.0f) {
|
|
/* Use uniform as a fallback if we can't sample the map. */
|
|
*pdf = 1.0f / M_4PI_F;
|
|
return sample_uniform_sphere(randu, randv);
|
|
}
|
|
else {
|
|
portal_sampling_pdf = 0.0f;
|
|
}
|
|
}
|
|
}
|
|
|
|
float3 D = background_map_sample(kg, randu, randv, pdf);
|
|
/* Use MIS if portals could be sampled as well. */
|
|
if(portal_sampling_pdf > 0.0f) {
|
|
float portal_pdf = background_portal_pdf(kg, P, D, -1, NULL);
|
|
*pdf = (portal_sampling_pdf * portal_pdf
|
|
+ (1.0f - portal_sampling_pdf) * (*pdf));
|
|
}
|
|
return D;
|
|
}
|
|
|
|
ccl_device float background_light_pdf(KernelGlobals *kg, float3 P, float3 direction)
|
|
{
|
|
/* Probability of sampling portals instead of the map. */
|
|
float portal_sampling_pdf = kernel_data.integrator.portal_pdf;
|
|
|
|
float portal_pdf = 0.0f, map_pdf = 0.0f;
|
|
if(portal_sampling_pdf > 0.0f) {
|
|
/* Evaluate PDF of sampling this direction by portal sampling. */
|
|
bool is_possible = false;
|
|
portal_pdf = background_portal_pdf(kg, P, direction, -1, &is_possible) * portal_sampling_pdf;
|
|
if(!is_possible) {
|
|
/* Portal sampling is not possible here because all portals point to the wrong side.
|
|
* If map sampling is possible, it would be used instead, otherwise fallback sampling is used. */
|
|
if(portal_sampling_pdf == 1.0f) {
|
|
return kernel_data.integrator.pdf_lights / M_4PI_F;
|
|
}
|
|
else {
|
|
/* Force map sampling. */
|
|
portal_sampling_pdf = 0.0f;
|
|
}
|
|
}
|
|
}
|
|
if(portal_sampling_pdf < 1.0f) {
|
|
/* Evaluate PDF of sampling this direction by map sampling. */
|
|
map_pdf = background_map_pdf(kg, direction) * (1.0f - portal_sampling_pdf);
|
|
}
|
|
return (portal_pdf + map_pdf) * kernel_data.integrator.pdf_lights;
|
|
}
|
|
#endif
|
|
|
|
/* Regular Light */
|
|
|
|
ccl_device_inline bool lamp_light_sample(KernelGlobals *kg,
|
|
int lamp,
|
|
float randu, float randv,
|
|
float3 P,
|
|
LightSample *ls)
|
|
{
|
|
const ccl_global KernelLight *klight = &kernel_tex_fetch(__lights, lamp);
|
|
LightType type = (LightType)klight->type;
|
|
ls->type = type;
|
|
ls->shader = klight->shader_id;
|
|
ls->object = PRIM_NONE;
|
|
ls->prim = PRIM_NONE;
|
|
ls->lamp = lamp;
|
|
ls->u = randu;
|
|
ls->v = randv;
|
|
|
|
if(type == LIGHT_DISTANT) {
|
|
/* distant light */
|
|
float3 lightD = make_float3(klight->co[0], klight->co[1], klight->co[2]);
|
|
float3 D = lightD;
|
|
float radius = klight->distant.radius;
|
|
float invarea = klight->distant.invarea;
|
|
|
|
if(radius > 0.0f)
|
|
D = distant_light_sample(D, radius, randu, randv);
|
|
|
|
ls->P = D;
|
|
ls->Ng = D;
|
|
ls->D = -D;
|
|
ls->t = FLT_MAX;
|
|
|
|
float costheta = dot(lightD, D);
|
|
ls->pdf = invarea/(costheta*costheta*costheta);
|
|
ls->eval_fac = ls->pdf;
|
|
}
|
|
#ifdef __BACKGROUND_MIS__
|
|
else if(type == LIGHT_BACKGROUND) {
|
|
/* infinite area light (e.g. light dome or env light) */
|
|
float3 D = -background_light_sample(kg, P, randu, randv, &ls->pdf);
|
|
|
|
ls->P = D;
|
|
ls->Ng = D;
|
|
ls->D = -D;
|
|
ls->t = FLT_MAX;
|
|
ls->eval_fac = 1.0f;
|
|
}
|
|
#endif
|
|
else {
|
|
ls->P = make_float3(klight->co[0], klight->co[1], klight->co[2]);
|
|
|
|
if(type == LIGHT_POINT || type == LIGHT_SPOT) {
|
|
float radius = klight->spot.radius;
|
|
|
|
if(radius > 0.0f)
|
|
/* sphere light */
|
|
ls->P += sphere_light_sample(P, ls->P, radius, randu, randv);
|
|
|
|
ls->D = normalize_len(ls->P - P, &ls->t);
|
|
ls->Ng = -ls->D;
|
|
|
|
float invarea = klight->spot.invarea;
|
|
ls->eval_fac = (0.25f*M_1_PI_F)*invarea;
|
|
ls->pdf = invarea;
|
|
|
|
if(type == LIGHT_SPOT) {
|
|
/* spot light attenuation */
|
|
float3 dir = make_float3(klight->spot.dir[0],
|
|
klight->spot.dir[1],
|
|
klight->spot.dir[2]);
|
|
ls->eval_fac *= spot_light_attenuation(dir,
|
|
klight->spot.spot_angle,
|
|
klight->spot.spot_smooth,
|
|
ls);
|
|
if(ls->eval_fac == 0.0f) {
|
|
return false;
|
|
}
|
|
}
|
|
float2 uv = map_to_sphere(ls->Ng);
|
|
ls->u = uv.x;
|
|
ls->v = uv.y;
|
|
|
|
ls->pdf *= lamp_light_pdf(kg, ls->Ng, -ls->D, ls->t);
|
|
}
|
|
else {
|
|
/* area light */
|
|
float3 axisu = make_float3(klight->area.axisu[0],
|
|
klight->area.axisu[1],
|
|
klight->area.axisu[2]);
|
|
float3 axisv = make_float3(klight->area.axisv[0],
|
|
klight->area.axisv[1],
|
|
klight->area.axisv[2]);
|
|
float3 D = make_float3(klight->area.dir[0],
|
|
klight->area.dir[1],
|
|
klight->area.dir[2]);
|
|
float invarea = fabsf(klight->area.invarea);
|
|
bool is_round = (klight->area.invarea < 0.0f);
|
|
|
|
if(dot(ls->P - P, D) > 0.0f) {
|
|
return false;
|
|
}
|
|
|
|
float3 inplane;
|
|
|
|
if(is_round) {
|
|
inplane = ellipse_sample(axisu*0.5f, axisv*0.5f, randu, randv);
|
|
ls->P += inplane;
|
|
ls->pdf = invarea;
|
|
}
|
|
else {
|
|
inplane = ls->P;
|
|
ls->pdf = rect_light_sample(P, &ls->P,
|
|
axisu, axisv,
|
|
randu, randv,
|
|
true);
|
|
inplane = ls->P - inplane;
|
|
}
|
|
|
|
ls->u = dot(inplane, axisu) * (1.0f / dot(axisu, axisu)) + 0.5f;
|
|
ls->v = dot(inplane, axisv) * (1.0f / dot(axisv, axisv)) + 0.5f;
|
|
|
|
ls->Ng = D;
|
|
ls->D = normalize_len(ls->P - P, &ls->t);
|
|
|
|
ls->eval_fac = 0.25f*invarea;
|
|
if(is_round) {
|
|
ls->pdf *= lamp_light_pdf(kg, D, -ls->D, ls->t);
|
|
}
|
|
}
|
|
}
|
|
|
|
ls->pdf *= kernel_data.integrator.pdf_lights;
|
|
|
|
return (ls->pdf > 0.0f);
|
|
}
|
|
|
|
ccl_device bool lamp_light_eval(KernelGlobals *kg, int lamp, float3 P, float3 D, float t, LightSample *ls)
|
|
{
|
|
const ccl_global KernelLight *klight = &kernel_tex_fetch(__lights, lamp);
|
|
LightType type = (LightType)klight->type;
|
|
ls->type = type;
|
|
ls->shader = klight->shader_id;
|
|
ls->object = PRIM_NONE;
|
|
ls->prim = PRIM_NONE;
|
|
ls->lamp = lamp;
|
|
/* todo: missing texture coordinates */
|
|
ls->u = 0.0f;
|
|
ls->v = 0.0f;
|
|
|
|
if(!(ls->shader & SHADER_USE_MIS))
|
|
return false;
|
|
|
|
if(type == LIGHT_DISTANT) {
|
|
/* distant light */
|
|
float radius = klight->distant.radius;
|
|
|
|
if(radius == 0.0f)
|
|
return false;
|
|
if(t != FLT_MAX)
|
|
return false;
|
|
|
|
/* a distant light is infinitely far away, but equivalent to a disk
|
|
* shaped light exactly 1 unit away from the current shading point.
|
|
*
|
|
* radius t^2/cos(theta)
|
|
* <----------> t = sqrt(1^2 + tan(theta)^2)
|
|
* tan(th) area = radius*radius*pi
|
|
* <----->
|
|
* \ | (1 + tan(theta)^2)/cos(theta)
|
|
* \ | (1 + tan(acos(cos(theta)))^2)/cos(theta)
|
|
* t \th| 1 simplifies to
|
|
* \-| 1/(cos(theta)^3)
|
|
* \| magic!
|
|
* P
|
|
*/
|
|
|
|
float3 lightD = make_float3(klight->co[0], klight->co[1], klight->co[2]);
|
|
float costheta = dot(-lightD, D);
|
|
float cosangle = klight->distant.cosangle;
|
|
|
|
if(costheta < cosangle)
|
|
return false;
|
|
|
|
ls->P = -D;
|
|
ls->Ng = -D;
|
|
ls->D = D;
|
|
ls->t = FLT_MAX;
|
|
|
|
/* compute pdf */
|
|
float invarea = klight->distant.invarea;
|
|
ls->pdf = invarea/(costheta*costheta*costheta);
|
|
ls->eval_fac = ls->pdf;
|
|
}
|
|
else if(type == LIGHT_POINT || type == LIGHT_SPOT) {
|
|
float3 lightP = make_float3(klight->co[0], klight->co[1], klight->co[2]);
|
|
|
|
float radius = klight->spot.radius;
|
|
|
|
/* sphere light */
|
|
if(radius == 0.0f)
|
|
return false;
|
|
|
|
if(!ray_aligned_disk_intersect(P, D, t,
|
|
lightP, radius, &ls->P, &ls->t))
|
|
{
|
|
return false;
|
|
}
|
|
|
|
ls->Ng = -D;
|
|
ls->D = D;
|
|
|
|
float invarea = klight->spot.invarea;
|
|
ls->eval_fac = (0.25f*M_1_PI_F)*invarea;
|
|
ls->pdf = invarea;
|
|
|
|
if(type == LIGHT_SPOT) {
|
|
/* spot light attenuation */
|
|
float3 dir = make_float3(klight->spot.dir[0],
|
|
klight->spot.dir[1],
|
|
klight->spot.dir[2]);
|
|
ls->eval_fac *= spot_light_attenuation(dir,
|
|
klight->spot.spot_angle,
|
|
klight->spot.spot_smooth,
|
|
ls);
|
|
|
|
if(ls->eval_fac == 0.0f)
|
|
return false;
|
|
}
|
|
float2 uv = map_to_sphere(ls->Ng);
|
|
ls->u = uv.x;
|
|
ls->v = uv.y;
|
|
|
|
/* compute pdf */
|
|
if(ls->t != FLT_MAX)
|
|
ls->pdf *= lamp_light_pdf(kg, ls->Ng, -ls->D, ls->t);
|
|
}
|
|
else if(type == LIGHT_AREA) {
|
|
/* area light */
|
|
float invarea = fabsf(klight->area.invarea);
|
|
bool is_round = (klight->area.invarea < 0.0f);
|
|
if(invarea == 0.0f)
|
|
return false;
|
|
|
|
float3 axisu = make_float3(klight->area.axisu[0],
|
|
klight->area.axisu[1],
|
|
klight->area.axisu[2]);
|
|
float3 axisv = make_float3(klight->area.axisv[0],
|
|
klight->area.axisv[1],
|
|
klight->area.axisv[2]);
|
|
float3 Ng = make_float3(klight->area.dir[0],
|
|
klight->area.dir[1],
|
|
klight->area.dir[2]);
|
|
|
|
/* one sided */
|
|
if(dot(D, Ng) >= 0.0f)
|
|
return false;
|
|
|
|
float3 light_P = make_float3(klight->co[0], klight->co[1], klight->co[2]);
|
|
|
|
if(!ray_quad_intersect(P, D, 0.0f, t, light_P,
|
|
axisu, axisv, Ng,
|
|
&ls->P, &ls->t,
|
|
&ls->u, &ls->v,
|
|
is_round))
|
|
{
|
|
return false;
|
|
}
|
|
|
|
ls->D = D;
|
|
ls->Ng = Ng;
|
|
if(is_round) {
|
|
ls->pdf = invarea * lamp_light_pdf(kg, Ng, -D, ls->t);
|
|
}
|
|
else {
|
|
ls->pdf = rect_light_sample(P, &light_P, axisu, axisv, 0, 0, false);
|
|
}
|
|
ls->eval_fac = 0.25f*invarea;
|
|
}
|
|
else {
|
|
return false;
|
|
}
|
|
|
|
ls->pdf *= kernel_data.integrator.pdf_lights;
|
|
|
|
return true;
|
|
}
|
|
|
|
/* Triangle Light */
|
|
|
|
/* returns true if the triangle is has motion blur or an instancing transform applied */
|
|
ccl_device_inline bool triangle_world_space_vertices(KernelGlobals *kg, int object, int prim, float time, float3 V[3])
|
|
{
|
|
bool has_motion = false;
|
|
const int object_flag = kernel_tex_fetch(__object_flag, object);
|
|
|
|
if(object_flag & SD_OBJECT_HAS_VERTEX_MOTION && time >= 0.0f) {
|
|
motion_triangle_vertices(kg, object, prim, time, V);
|
|
has_motion = true;
|
|
}
|
|
else {
|
|
triangle_vertices(kg, prim, V);
|
|
}
|
|
|
|
#ifdef __INSTANCING__
|
|
if(!(object_flag & SD_OBJECT_TRANSFORM_APPLIED)) {
|
|
# ifdef __OBJECT_MOTION__
|
|
float object_time = (time >= 0.0f) ? time : 0.5f;
|
|
Transform tfm = object_fetch_transform_motion_test(kg, object, object_time, NULL);
|
|
# else
|
|
Transform tfm = object_fetch_transform(kg, object, OBJECT_TRANSFORM);
|
|
# endif
|
|
V[0] = transform_point(&tfm, V[0]);
|
|
V[1] = transform_point(&tfm, V[1]);
|
|
V[2] = transform_point(&tfm, V[2]);
|
|
has_motion = true;
|
|
}
|
|
#endif
|
|
return has_motion;
|
|
}
|
|
|
|
ccl_device_inline float triangle_light_pdf_area(KernelGlobals *kg, const float3 Ng, const float3 I, float t)
|
|
{
|
|
float pdf = kernel_data.integrator.pdf_triangles;
|
|
float cos_pi = fabsf(dot(Ng, I));
|
|
|
|
if(cos_pi == 0.0f)
|
|
return 0.0f;
|
|
|
|
return t*t*pdf/cos_pi;
|
|
}
|
|
|
|
ccl_device_forceinline float triangle_light_pdf(KernelGlobals *kg, ShaderData *sd, float t)
|
|
{
|
|
/* A naive heuristic to decide between costly solid angle sampling
|
|
* and simple area sampling, comparing the distance to the triangle plane
|
|
* to the length of the edges of the triangle. */
|
|
|
|
float3 V[3];
|
|
bool has_motion = triangle_world_space_vertices(kg, sd->object, sd->prim, sd->time, V);
|
|
|
|
const float3 e0 = V[1] - V[0];
|
|
const float3 e1 = V[2] - V[0];
|
|
const float3 e2 = V[2] - V[1];
|
|
const float longest_edge_squared = max(len_squared(e0), max(len_squared(e1), len_squared(e2)));
|
|
const float3 N = cross(e0, e1);
|
|
const float distance_to_plane = fabsf(dot(N, sd->I * t))/dot(N, N);
|
|
|
|
if(longest_edge_squared > distance_to_plane*distance_to_plane) {
|
|
/* sd contains the point on the light source
|
|
* calculate Px, the point that we're shading */
|
|
const float3 Px = sd->P + sd->I * t;
|
|
const float3 v0_p = V[0] - Px;
|
|
const float3 v1_p = V[1] - Px;
|
|
const float3 v2_p = V[2] - Px;
|
|
|
|
const float3 u01 = safe_normalize(cross(v0_p, v1_p));
|
|
const float3 u02 = safe_normalize(cross(v0_p, v2_p));
|
|
const float3 u12 = safe_normalize(cross(v1_p, v2_p));
|
|
|
|
const float alpha = fast_acosf(dot(u02, u01));
|
|
const float beta = fast_acosf(-dot(u01, u12));
|
|
const float gamma = fast_acosf(dot(u02, u12));
|
|
const float solid_angle = alpha + beta + gamma - M_PI_F;
|
|
|
|
/* pdf_triangles is calculated over triangle area, but we're not sampling over its area */
|
|
if(UNLIKELY(solid_angle == 0.0f)) {
|
|
return 0.0f;
|
|
}
|
|
else {
|
|
float area = 1.0f;
|
|
if(has_motion) {
|
|
/* get the center frame vertices, this is what the PDF was calculated from */
|
|
triangle_world_space_vertices(kg, sd->object, sd->prim, -1.0f, V);
|
|
area = triangle_area(V[0], V[1], V[2]);
|
|
}
|
|
else {
|
|
area = 0.5f * len(N);
|
|
}
|
|
const float pdf = area * kernel_data.integrator.pdf_triangles;
|
|
return pdf / solid_angle;
|
|
}
|
|
}
|
|
else {
|
|
float pdf = triangle_light_pdf_area(kg, sd->Ng, sd->I, t);
|
|
if(has_motion) {
|
|
const float area = 0.5f * len(N);
|
|
if(UNLIKELY(area == 0.0f)) {
|
|
return 0.0f;
|
|
}
|
|
/* scale the PDF.
|
|
* area = the area the sample was taken from
|
|
* area_pre = the are from which pdf_triangles was calculated from */
|
|
triangle_world_space_vertices(kg, sd->object, sd->prim, -1.0f, V);
|
|
const float area_pre = triangle_area(V[0], V[1], V[2]);
|
|
pdf = pdf * area_pre / area;
|
|
}
|
|
return pdf;
|
|
}
|
|
}
|
|
|
|
ccl_device_forceinline void triangle_light_sample(KernelGlobals *kg, int prim, int object,
|
|
float randu, float randv, float time, LightSample *ls, const float3 P)
|
|
{
|
|
/* A naive heuristic to decide between costly solid angle sampling
|
|
* and simple area sampling, comparing the distance to the triangle plane
|
|
* to the length of the edges of the triangle. */
|
|
|
|
float3 V[3];
|
|
bool has_motion = triangle_world_space_vertices(kg, object, prim, time, V);
|
|
|
|
const float3 e0 = V[1] - V[0];
|
|
const float3 e1 = V[2] - V[0];
|
|
const float3 e2 = V[2] - V[1];
|
|
const float longest_edge_squared = max(len_squared(e0), max(len_squared(e1), len_squared(e2)));
|
|
const float3 N0 = cross(e0, e1);
|
|
float Nl = 0.0f;
|
|
ls->Ng = safe_normalize_len(N0, &Nl);
|
|
float area = 0.5f * Nl;
|
|
|
|
/* flip normal if necessary */
|
|
const int object_flag = kernel_tex_fetch(__object_flag, object);
|
|
if(object_flag & SD_OBJECT_NEGATIVE_SCALE_APPLIED) {
|
|
ls->Ng = -ls->Ng;
|
|
}
|
|
ls->eval_fac = 1.0f;
|
|
ls->shader = kernel_tex_fetch(__tri_shader, prim);
|
|
ls->object = object;
|
|
ls->prim = prim;
|
|
ls->lamp = LAMP_NONE;
|
|
ls->shader |= SHADER_USE_MIS;
|
|
ls->type = LIGHT_TRIANGLE;
|
|
|
|
float distance_to_plane = fabsf(dot(N0, V[0] - P)/dot(N0, N0));
|
|
|
|
if(longest_edge_squared > distance_to_plane*distance_to_plane) {
|
|
/* see James Arvo, "Stratified Sampling of Spherical Triangles"
|
|
* http://www.graphics.cornell.edu/pubs/1995/Arv95c.pdf */
|
|
|
|
/* project the triangle to the unit sphere
|
|
* and calculate its edges and angles */
|
|
const float3 v0_p = V[0] - P;
|
|
const float3 v1_p = V[1] - P;
|
|
const float3 v2_p = V[2] - P;
|
|
|
|
const float3 u01 = safe_normalize(cross(v0_p, v1_p));
|
|
const float3 u02 = safe_normalize(cross(v0_p, v2_p));
|
|
const float3 u12 = safe_normalize(cross(v1_p, v2_p));
|
|
|
|
const float3 A = safe_normalize(v0_p);
|
|
const float3 B = safe_normalize(v1_p);
|
|
const float3 C = safe_normalize(v2_p);
|
|
|
|
const float cos_alpha = dot(u02, u01);
|
|
const float cos_beta = -dot(u01, u12);
|
|
const float cos_gamma = dot(u02, u12);
|
|
|
|
/* calculate dihedral angles */
|
|
const float alpha = fast_acosf(cos_alpha);
|
|
const float beta = fast_acosf(cos_beta);
|
|
const float gamma = fast_acosf(cos_gamma);
|
|
/* the area of the unit spherical triangle = solid angle */
|
|
const float solid_angle = alpha + beta + gamma - M_PI_F;
|
|
|
|
/* precompute a few things
|
|
* these could be re-used to take several samples
|
|
* as they are independent of randu/randv */
|
|
const float cos_c = dot(A, B);
|
|
const float sin_alpha = fast_sinf(alpha);
|
|
const float product = sin_alpha * cos_c;
|
|
|
|
/* Select a random sub-area of the spherical triangle
|
|
* and calculate the third vertex C_ of that new triangle */
|
|
const float phi = randu * solid_angle - alpha;
|
|
float s, t;
|
|
fast_sincosf(phi, &s, &t);
|
|
const float u = t - cos_alpha;
|
|
const float v = s + product;
|
|
|
|
const float3 U = safe_normalize(C - dot(C, A) * A);
|
|
|
|
float q = 1.0f;
|
|
const float det = ((v * s + u * t) * sin_alpha);
|
|
if(det != 0.0f) {
|
|
q = ((v * t - u * s) * cos_alpha - v) / det;
|
|
}
|
|
const float temp = max(1.0f - q*q, 0.0f);
|
|
|
|
const float3 C_ = safe_normalize(q * A + sqrtf(temp) * U);
|
|
|
|
/* Finally, select a random point along the edge of the new triangle
|
|
* That point on the spherical triangle is the sampled ray direction */
|
|
const float z = 1.0f - randv * (1.0f - dot(C_, B));
|
|
ls->D = z * B + safe_sqrtf(1.0f - z*z) * safe_normalize(C_ - dot(C_, B) * B);
|
|
|
|
/* calculate intersection with the planar triangle */
|
|
if(!ray_triangle_intersect(P, ls->D, FLT_MAX,
|
|
#if defined(__KERNEL_SSE2__) && defined(__KERNEL_SSE__)
|
|
(ssef*)V,
|
|
#else
|
|
V[0], V[1], V[2],
|
|
#endif
|
|
&ls->u, &ls->v, &ls->t)) {
|
|
ls->pdf = 0.0f;
|
|
return;
|
|
}
|
|
|
|
ls->P = P + ls->D * ls->t;
|
|
|
|
/* pdf_triangles is calculated over triangle area, but we're sampling over solid angle */
|
|
if(UNLIKELY(solid_angle == 0.0f)) {
|
|
ls->pdf = 0.0f;
|
|
return;
|
|
}
|
|
else {
|
|
if(has_motion) {
|
|
/* get the center frame vertices, this is what the PDF was calculated from */
|
|
triangle_world_space_vertices(kg, object, prim, -1.0f, V);
|
|
area = triangle_area(V[0], V[1], V[2]);
|
|
}
|
|
const float pdf = area * kernel_data.integrator.pdf_triangles;
|
|
ls->pdf = pdf / solid_angle;
|
|
}
|
|
}
|
|
else {
|
|
/* compute random point in triangle */
|
|
randu = sqrtf(randu);
|
|
|
|
const float u = 1.0f - randu;
|
|
const float v = randv*randu;
|
|
const float t = 1.0f - u - v;
|
|
ls->P = u * V[0] + v * V[1] + t * V[2];
|
|
/* compute incoming direction, distance and pdf */
|
|
ls->D = normalize_len(ls->P - P, &ls->t);
|
|
ls->pdf = triangle_light_pdf_area(kg, ls->Ng, -ls->D, ls->t);
|
|
if(has_motion && area != 0.0f) {
|
|
/* scale the PDF.
|
|
* area = the area the sample was taken from
|
|
* area_pre = the are from which pdf_triangles was calculated from */
|
|
triangle_world_space_vertices(kg, object, prim, -1.0f, V);
|
|
const float area_pre = triangle_area(V[0], V[1], V[2]);
|
|
ls->pdf = ls->pdf * area_pre / area;
|
|
}
|
|
ls->u = u;
|
|
ls->v = v;
|
|
}
|
|
}
|
|
|
|
/* Light Distribution */
|
|
|
|
ccl_device int light_distribution_sample(KernelGlobals *kg, float *randu)
|
|
{
|
|
/* 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
|
|
* arbitrary shaders. */
|
|
int first = 0;
|
|
int len = kernel_data.integrator.num_distribution + 1;
|
|
float r = *randu;
|
|
|
|
while(len > 0) {
|
|
int half_len = len >> 1;
|
|
int middle = first + half_len;
|
|
|
|
if(r < kernel_tex_fetch(__light_distribution, middle).totarea) {
|
|
len = half_len;
|
|
}
|
|
else {
|
|
first = middle + 1;
|
|
len = len - half_len - 1;
|
|
}
|
|
}
|
|
|
|
/* Clamping should not be needed but float rounding errors seem to
|
|
* make this fail on rare occasions. */
|
|
int index = clamp(first-1, 0, kernel_data.integrator.num_distribution-1);
|
|
|
|
/* Rescale to reuse random number. this helps the 2D samples within
|
|
* each area light be stratified as well. */
|
|
float distr_min = kernel_tex_fetch(__light_distribution, index).totarea;
|
|
float distr_max = kernel_tex_fetch(__light_distribution, index+1).totarea;
|
|
*randu = (r - distr_min)/(distr_max - distr_min);
|
|
|
|
return index;
|
|
}
|
|
|
|
/* Generic Light */
|
|
|
|
ccl_device bool light_select_reached_max_bounces(KernelGlobals *kg, int index, int bounce)
|
|
{
|
|
return (bounce > kernel_tex_fetch(__lights, index).max_bounces);
|
|
}
|
|
|
|
ccl_device_noinline bool light_sample(KernelGlobals *kg,
|
|
float randu,
|
|
float randv,
|
|
float time,
|
|
float3 P,
|
|
int bounce,
|
|
LightSample *ls)
|
|
{
|
|
/* sample index */
|
|
int index = light_distribution_sample(kg, &randu);
|
|
|
|
/* fetch light data */
|
|
const ccl_global KernelLightDistribution *kdistribution = &kernel_tex_fetch(__light_distribution, index);
|
|
int prim = kdistribution->prim;
|
|
|
|
if(prim >= 0) {
|
|
int object = kdistribution->mesh_light.object_id;
|
|
int shader_flag = kdistribution->mesh_light.shader_flag;
|
|
|
|
triangle_light_sample(kg, prim, object, randu, randv, time, ls, P);
|
|
ls->shader |= shader_flag;
|
|
return (ls->pdf > 0.0f);
|
|
}
|
|
else {
|
|
int lamp = -prim-1;
|
|
|
|
if(UNLIKELY(light_select_reached_max_bounces(kg, lamp, bounce))) {
|
|
return false;
|
|
}
|
|
|
|
return lamp_light_sample(kg, lamp, randu, randv, P, ls);
|
|
}
|
|
}
|
|
|
|
ccl_device int light_select_num_samples(KernelGlobals *kg, int index)
|
|
{
|
|
return kernel_tex_fetch(__lights, index).samples;
|
|
}
|
|
|
|
CCL_NAMESPACE_END
|