add more to task7

Author: lumixraku

.DS_Store

@@ -78,7 +78,7 @@ PS: 这里的H 表示半球面
 
 关于此渲染方程 Read More  https://zh.wikipedia.org/wiki/%E6%B8%B2%E6%9F%93%E6%96%B9%E7%A8%8B
 
-![image](https://raw.githubusercontent.com/lumixraku/NotesForGraphics/master/images/rendering1.png)
+![image](https://raw.githubusercontent.com/lumixraku/NotesForGraphics/master/images/rendering1.jpg)
 
 
 Lo(p, ω0) 是点p在出射ω0方向的最终渲染结果

Notes15.md

@@ -170,7 +170,7 @@ PS: 有的地方也称为面积形式的的渲染方程， 并且将前面介绍
 
 来自于光源的部分， 可以使用对光源采样。其他非光源的贡献，继续使用RR
 ![image](https://raw.githubusercontent.com/lumixraku/NotesForGraphics/master/images/tracing15.jpg)
-
+PS dA 是光源上的一个小的表面
 
 ![image](https://raw.githubusercontent.com/lumixraku/NotesForGraphics/master/images/tracing16.jpg)
 

Notes16.md

@@ -2,6 +2,51 @@
     "files.associations": {
         "limits": "cpp",
         "array": "cpp",
-        "cmath": "cpp"
+        "cmath": "cpp",
+        "typeinfo": "cpp",
+        "atomic": "cpp",
+        "bit": "cpp",
+        "*.tcc": "cpp",
+        "cctype": "cpp",
+        "chrono": "cpp",
+        "clocale": "cpp",
+        "complex": "cpp",
+        "cstdarg": "cpp",
+        "cstddef": "cpp",
+        "cstdint": "cpp",
+        "cstdio": "cpp",
+        "cstdlib": "cpp",
+        "ctime": "cpp",
+        "cwchar": "cpp",
+        "cwctype": "cpp",
+        "deque": "cpp",
+        "unordered_map": "cpp",
+        "vector": "cpp",
+        "exception": "cpp",
+        "algorithm": "cpp",
+        "functional": "cpp",
+        "iterator": "cpp",
+        "memory": "cpp",
+        "memory_resource": "cpp",
+        "numeric": "cpp",
+        "optional": "cpp",
+        "random": "cpp",
+        "ratio": "cpp",
+        "string": "cpp",
+        "string_view": "cpp",
+        "system_error": "cpp",
+        "tuple": "cpp",
+        "type_traits": "cpp",
+        "utility": "cpp",
+        "fstream": "cpp",
+        "initializer_list": "cpp",
+        "iosfwd": "cpp",
+        "iostream": "cpp",
+        "istream": "cpp",
+        "new": "cpp",
+        "ostream": "cpp",
+        "sstream": "cpp",
+        "stdexcept": "cpp",
+        "streambuf": "cpp"
     }
 }

task7/task7/.vscode/settings.json

@@ -20,5 +20,37 @@
             landmarkType = "7">
          </BreakpointContent>
       </BreakpointProxy>
+      <BreakpointProxy
+         BreakpointExtensionID = "Xcode.Breakpoint.FileBreakpoint">
+         <BreakpointContent
+            uuid = "9F733401-2730-41AB-93A9-EF0543841AD0"
+            shouldBeEnabled = "Yes"
+            ignoreCount = "0"
+            continueAfterRunningActions = "No"
+            filePath = "task7/Scene.cpp"
+            startingColumnNumber = "9223372036854775807"
+            endingColumnNumber = "9223372036854775807"
+            startingLineNumber = "79"
+            endingLineNumber = "79"
+            landmarkName = "Scene::castRay(ray, depth)"
+            landmarkType = "7">
+         </BreakpointContent>
+      </BreakpointProxy>
+      <BreakpointProxy
+         BreakpointExtensionID = "Xcode.Breakpoint.FileBreakpoint">
+         <BreakpointContent
+            uuid = "5CF217F2-FDA8-4E2A-B0F5-F114137246C2"
+            shouldBeEnabled = "Yes"
+            ignoreCount = "0"
+            continueAfterRunningActions = "No"
+            filePath = "task7/Scene.cpp"
+            startingColumnNumber = "9223372036854775807"
+            endingColumnNumber = "9223372036854775807"
+            startingLineNumber = "78"
+            endingLineNumber = "78"
+            landmarkName = "Scene::castRay(ray, depth)"
+            landmarkType = "7">
+         </BreakpointContent>
+      </BreakpointProxy>
    </Breakpoints>
 </Bucket>

task7/task7/task7.xcodeproj/project.xcworkspace/xcuserdata/lilin.xcuserdatad/UserInterfaceState.xcuserstate

@@ -136,6 +136,8 @@ Vector3f Material::sample(const Vector3f &wi, const Vector3f &N){
         case DIFFUSE:
         {
             // uniform sample on the hemisphere
+            // 半球面采样
+            // 参考 https://000ddd00dd0d.github.io/2019/04/07/Spherical-Sampling/
             float x_1 = get_random_float(), x_2 = get_random_float();
             float z = std::fabs(1.0f - 2.0f * x_1);
             float r = std::sqrt(1.0f - z * z), phi = 2 * M_PI * x_2;

task7/task7/task7.xcodeproj/xcuserdata/lilin.xcuserdatad/xcdebugger/Breakpoints_v2.xcbkptlist

@@ -79,6 +79,8 @@ void Renderer::Render(const Scene& scene)
             Vector3f dir = normalize(Vector3f(-x, y, 1));
             thread_local Vector3f color;
             color = Vector3f(0);
+
+            // SPP 每个像素点多发出几条射线采样
             for (int k = 0; k < spp; k++){
                 color += scene.castRay(Ray(eye_pos, dir), 0) / spp;  
             }

task7/task7/task7/Material.hpp

@@ -20,7 +20,7 @@ void Scene::sampleLight(Intersection &pos, float &pdf) const
     float emit_area_sum = 0;
     for (uint32_t k = 0; k < objects.size(); ++k) {
         if (objects[k]->hasEmit()){
-            emit_area_sum += objects[k]->getArea();
+            emit_area_sum += objects[k]->getArea(); //物体的表面积
         }
     }
     float p = get_random_float() * emit_area_sum;
@@ -69,27 +69,30 @@ Vector3f Scene::castRay(const Ray &ray, int depth) const
     hitcolor = Vector3f(1);
     else if(intersection.happened)
     {
-        Vector3f wo = normalize(-ray.direction);
-        Vector3f p = intersection.coords;
-        Vector3f N = normalize(intersection.normal);
+        Vector3f wo = normalize(-ray.direction); // 光的出射方向
+        Vector3f p = intersection.coords;        // 射线和物体的坐标
+        Vector3f N = normalize(intersection.normal); 
 
         float pdf_light = 0.0f;
-        Intersection inter;
-        sampleLight(inter,pdf_light);
+        Intersection inter;   
+        sampleLight(inter,pdf_light); // 任意物体表面上任意一个点
         Vector3f x = inter.coords;
-        Vector3f ws = normalize(x-p);
+        Vector3f ws = normalize(x-p);     // 
         Vector3f NN = normalize(inter.normal);
 
         Vector3f L_dir = Vector3f(0);
-        //direct light
+        // direct light
+        // 这里的公式参考 Notes16 P43
         if((intersect(Ray(p,ws)).coords - x).norm() < 0.01)
         {
+            // inter.emit 是发光物体才有意义  不然inter.emit 是0
+            // eval(wo,ws,N)  返回的是一个漫反射系数
             L_dir = inter.emit * intersection.m->eval(wo,ws,N)*dotProduct(ws,N) * dotProduct(-ws,NN) / (((x-p).norm()* (x-p).norm()) * pdf_light);
         }
 
         Vector3f L_indir = Vector3f(0);
         float P_RR = get_random_float();
-        //indirect light
+        // indirect light
         if(P_RR < Scene::RussianRoulette)
         {
             Vector3f wi = intersection.m->sample(wo,N);

task7/task7/task7/Renderer.cpp

@@ -16,6 +16,7 @@ class Sphere : public Object{
     float radius, radius2;
     Material *m;
     float area;
+    // 初始化列表
     Sphere(const Vector3f &c, const float &r, Material* mt = new Material()) : center(c), radius(r), radius2(r * r), m(mt), area(4 * M_PI *r *r) {}
     bool intersect(const Ray& ray) {
         // analytic solution
@@ -24,6 +25,8 @@ class Sphere : public Object{
         float b = 2 * dotProduct(ray.direction, L);
         float c = dotProduct(L, L) - radius2;
         float t0, t1;
+
+        // 球表面积 S=4πr²
         float area = 4 * M_PI * radius2;
         if (!solveQuadratic(a, b, c, t0, t1)) return false;
         if (t0 < 0) t0 = t1;