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Light cdfs (#1066)
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@xelatihy
xelatihy authored Sep 2, 2020
1 parent 6669856 commit f5e360a
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Showing 2 changed files with 31 additions and 37 deletions.
57 changes: 28 additions & 29 deletions libs/yocto/yocto_trace.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2209,7 +2209,7 @@ static vec3f sample_lights(const trace_scene* scene, const trace_lights* lights,
auto light = lights->lights[light_id];
if (light->instance != nullptr) {
auto instance = light->instance;
auto element = sample_discrete_cdf(instance->shape->elements_cdf, rel);
auto element = sample_discrete_cdf(light->elements_cdf, rel);
auto uv = (!instance->shape->triangles.empty()) ? sample_triangle(ruv)
: ruv;
auto lposition = eval_position(light->instance, element, uv);
Expand All @@ -2218,7 +2218,7 @@ static vec3f sample_lights(const trace_scene* scene, const trace_lights* lights,
auto environment = light->environment;
if (environment->emission_tex != nullptr) {
auto emission_tex = environment->emission_tex;
auto idx = sample_discrete_cdf(environment->texels_cdf, rel);
auto idx = sample_discrete_cdf(light->elements_cdf, rel);
auto size = texture_size(emission_tex);
auto uv = vec2f{
((idx % size.x) + 0.5f) / size.x, ((idx / size.x) + 0.5f) / size.y};
Expand Down Expand Up @@ -2252,7 +2252,7 @@ static float sample_lights_pdf(const trace_scene* scene,
auto lnormal = eval_element_normal(
light->instance, intersection.element);
// prob triangle * area triangle = area triangle mesh
auto area = light->instance->shape->elements_cdf.back();
auto area = light->elements_cdf.back();
lpdf += distance_squared(lposition, position) /
(abs(dot(lnormal, direction)) * area);
// continue
Expand All @@ -2271,8 +2271,8 @@ static float sample_lights_pdf(const trace_scene* scene,
auto i = clamp((int)(texcoord.x * size.x), 0, size.x - 1);
auto j = clamp((int)(texcoord.y * size.y), 0, size.y - 1);
auto prob = sample_discrete_cdf_pdf(
light->environment->texels_cdf, j * size.x + i) /
light->environment->texels_cdf.back();
light->elements_cdf, j * size.x + i) /
light->elements_cdf.back();
auto angle = (2 * pif / size.x) * (pif / size.y) *
sin(pif * (j + 0.5f) / size.y);
pdf += prob / angle;
Expand Down Expand Up @@ -2844,50 +2844,49 @@ void init_lights(trace_lights* lights, const trace_scene* scene,
auto shape = instance->shape;
if (shape->triangles.empty() && shape->quads.empty()) continue;
if (progress_cb) progress_cb("build light", progress.x++, ++progress.y);
auto light = add_light(lights);
light->instance = instance;
light->environment = nullptr;
if (!shape->triangles.empty()) {
shape->elements_cdf = vector<float>(shape->triangles.size());
for (auto idx = 0; idx < shape->elements_cdf.size(); idx++) {
light->elements_cdf = vector<float>(shape->triangles.size());
for (auto idx = 0; idx < light->elements_cdf.size(); idx++) {
auto& t = shape->triangles[idx];
shape->elements_cdf[idx] = triangle_area(shape->positions[t.x],
light->elements_cdf[idx] = triangle_area(shape->positions[t.x],
shape->positions[t.y], shape->positions[t.z]);
if (idx != 0) shape->elements_cdf[idx] += shape->elements_cdf[idx - 1];
if (idx != 0) light->elements_cdf[idx] += light->elements_cdf[idx - 1];
}
}
if (!shape->quads.empty()) {
shape->elements_cdf = vector<float>(shape->quads.size());
for (auto idx = 0; idx < shape->elements_cdf.size(); idx++) {
light->elements_cdf = vector<float>(shape->quads.size());
for (auto idx = 0; idx < light->elements_cdf.size(); idx++) {
auto& t = shape->quads[idx];
shape->elements_cdf[idx] = quad_area(shape->positions[t.x],
light->elements_cdf[idx] = quad_area(shape->positions[t.x],
shape->positions[t.y], shape->positions[t.z],
shape->positions[t.w]);
if (idx != 0) shape->elements_cdf[idx] += shape->elements_cdf[idx - 1];
if (idx != 0) light->elements_cdf[idx] += light->elements_cdf[idx - 1];
}
}
auto light = add_light(lights);
light->instance = instance;
light->environment = nullptr;
}
for (auto environment : scene->environments) {
if (environment->emission == zero3f) continue;
if (progress_cb) progress_cb("build light", progress.x++, ++progress.y);
auto light = add_light(lights);
light->instance = nullptr;
light->environment = environment;
if (environment->emission_tex != nullptr) {
auto texture = environment->emission_tex;
auto size = texture_size(texture);
environment->texels_cdf = vector<float>(size.x * size.y);
auto texture = environment->emission_tex;
auto size = texture_size(texture);
light->elements_cdf = vector<float>(size.x * size.y);
if (size != zero2i) {
for (auto i = 0; i < environment->texels_cdf.size(); i++) {
auto ij = vec2i{i % size.x, i / size.x};
auto th = (ij.y + 0.5f) * pif / size.y;
auto value = lookup_texture(texture, ij);
environment->texels_cdf[i] = max(value) * sin(th);
if (i != 0)
environment->texels_cdf[i] += environment->texels_cdf[i - 1];
for (auto i = 0; i < light->elements_cdf.size(); i++) {
auto ij = vec2i{i % size.x, i / size.x};
auto th = (ij.y + 0.5f) * pif / size.y;
auto value = lookup_texture(texture, ij);
light->elements_cdf[i] = max(value) * sin(th);
if (i != 0) light->elements_cdf[i] += light->elements_cdf[i - 1];
}
}
}
auto light = add_light(lights);
light->instance = nullptr;
light->environment = environment;
}

// handle progress
Expand Down
11 changes: 3 additions & 8 deletions libs/yocto/yocto_trace.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -199,9 +199,6 @@ struct trace_shape {
RTCScene embree_bvh = nullptr;
#endif

// element cdf for sampling
vector<float> elements_cdf = {};

// cleanup
~trace_shape();
};
Expand All @@ -218,9 +215,6 @@ struct trace_environment {
frame3f frame = identity3x4f;
vec3f emission = {0, 0, 0};
trace_texture* emission_tex = nullptr;

// computed properties
vector<float> texels_cdf = {};
};

// Scene comprised an array of objects whose memory is owened by the scene.
Expand Down Expand Up @@ -537,8 +531,9 @@ namespace yocto {

// Scene lights used during rendering. These are created automatically.
struct trace_light {
trace_instance* instance = nullptr;
trace_environment* environment = nullptr;
trace_instance* instance = nullptr;
trace_environment* environment = nullptr;
vector<float> elements_cdf = {};
};

// Scene lights
Expand Down

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