fix directSampleLight bug

README.md

@@ -3,3 +3,6 @@
 - examples/area-lights
 - examples/two-spotlights
 - examples/bunny
+
+## TODO
+- 对mesh和sphere实现表面采样（目前只有parallelogram可以配置为面光源）

examples/bunny/scene.json

@@ -1,6 +1,6 @@
 {
  "output" : {
- "filename" : "cornell-18.hdr"
+ "filename" : "cornell-18.png"
  },
  "sampler" : {
  "type" : "independent",
@@ -24,7 +24,7 @@
  }
  },
  "integrator" : {
- "type" : "directSampleBSDF"
+ "type" : "directSampleLight"
  },
  "scene" : {
  "shapes" : [

src/CoreLayer/Math/Distribution.h

@@ -24,6 +24,11 @@ template <typename T> class Distribution {
  }
 
  T sample(float sample, float *pdf) const {
+ if (cdf.size() == 1) {
+ // no data in distribution
+ *pdf = .0f;
+ return T();
+ }
  auto entry = std::lower_bound(cdf.cbegin(), cdf.cend(), sample);
  size_t index = entry - cdf.cbegin() - 1;
  *pdf = cdf[index + 1] - cdf[index];

src/FunctionLayer/Integrator/DirectIntegrator.cpp

@@ -37,20 +37,23 @@ DirectIntegratorSampleLight::li(const Ray &ray, const Scene &scene,
  //* 从场景中采样一个光源
  float pdfLight = .0f;
  auto light = scene.sampleLight(sampler->next1D(), &pdfLight);
- //* 在光源上采样出一个点
- auto lightSampleResult = light->sample(intersection, sampler->next2D());
 
- //* 测试shadowray是否被场景遮挡
- Ray shadowRay{intersection.position, lightSampleResult.direction, 1e-4f,
- lightSampleResult.distance};
- auto occlude = scene.rayIntersect(shadowRay);
- if (!occlude.has_value()) {
- auto material = intersection.shape->material;
- auto bsdf = material->computeBSDF(intersection);
- Spectrum f = bsdf->f(-ray.direction, shadowRay.direction);
- lightSampleResult.pdf *= pdfLight;
- float pdf = convertPDF(lightSampleResult, intersection);
- spectrum += lightSampleResult.energy * f / pdf;
+ if (light && pdfLight != .0f) {
+ //* 在光源上采样出一个点
+ auto lightSampleResult = light->sample(intersection, sampler->next2D());
+
+ //* 测试shadowray是否被场景遮挡
+ Ray shadowRay{intersection.position, lightSampleResult.direction, 1e-4f,
+ lightSampleResult.distance};
+ auto occlude = scene.rayIntersect(shadowRay);
+ if (!occlude.has_value()) {
+ auto material = intersection.shape->material;
+ auto bsdf = material->computeBSDF(intersection);
+ Spectrum f = bsdf->f(-ray.direction, shadowRay.direction);
+ lightSampleResult.pdf *= pdfLight;
+ float pdf = convertPDF(lightSampleResult, intersection);
+ spectrum += lightSampleResult.energy * f / pdf;
+ }
  }
  return spectrum;
 }

src/main.cpp

@@ -9,6 +9,7 @@
 #include <ResourceLayer/Image.h>
 #include <ResourceLayer/JsonUtil.h>
 #include <fstream>
+#include <regex>
 #include <stdio.h>
 
 int main(int argc, char **argv) {
@@ -35,6 +36,15 @@ int main(int argc, char **argv) {
  camera->film->deposit({x, y}, li / spp);
  }
  }
- camera->film->saveHDR(
- fetchRequired<std::string>(json["output"], "filename").c_str());
+
+ //* 目前支持输出为png/hdr两种格式
+ std::string outputName =
+ fetchRequired<std::string>(json["output"], "filename");
+ if (std::regex_match(outputName, std::regex("(.*)(\\.png)"))) {
+ camera->film->savePNG(outputName.c_str());
+ } else if (std::regex_match(outputName, std::regex("(.*)(\\.hdr)"))) {
+ camera->film->saveHDR(outputName.c_str());
+ } else {
+ std::cout << "Only support output as PNG/HDR\n";
+ }
 }