add more to task5

Author: lumixraku

Notes8.md

@@ -1,6 +1,22 @@
 # Lecture 08 Shading 2
 
-## 高光模型
+## 高光模型 Phong
+和观察角度有关
+
+Phong 重点在于计算 reflection
+
+V 是观察角度  R 是反射方向
+```
+spec = pow(max(dot(V, R), 0.0), alpha);
+```
+
+Read More https://www.qiujiawei.com/lighting-1/
+
+
+
+## 高光模型 Blinn-Phong
+
+和观察角度有关
 
 ![image](https://raw.githubusercontent.com/lumixraku/NotesForGraphics/master/images/shading4.jpg)
 
@@ -18,7 +34,7 @@ PS: cosα 可以写成 法线n 点乘 半程向量h
 
 ![image](https://raw.githubusercontent.com/lumixraku/NotesForGraphics/master/images/shading6.jpg)
 
-PS: 另外需要说明的是入射光方向和中学物理中的方向是相反的， 这个公式中入射光的方向就是用光源减去点
+PS: 另外需要说明的是入射光方向其实是指光源的方向，而不是光线的方向。
 
 ## 环境光
 

task5/task5/task5.xcodeproj/project.xcworkspace/xcuserdata/lilin.xcuserdatad/UserInterfaceState.xcuserstate

@@ -20,5 +20,21 @@
             landmarkType = "9">
          </BreakpointContent>
       </BreakpointProxy>
+      <BreakpointProxy
+         BreakpointExtensionID = "Xcode.Breakpoint.FileBreakpoint">
+         <BreakpointContent
+            uuid = "9DBD7F7D-7366-48DC-BB77-BB49588F9318"
+            shouldBeEnabled = "No"
+            ignoreCount = "0"
+            continueAfterRunningActions = "No"
+            filePath = "task5/Renderer.cpp"
+            startingColumnNumber = "9223372036854775807"
+            endingColumnNumber = "9223372036854775807"
+            startingLineNumber = "227"
+            endingLineNumber = "227"
+            landmarkName = "castRay(orig, dir, scene, depth)"
+            landmarkType = "9">
+         </BreakpointContent>
+      </BreakpointProxy>
    </Breakpoints>
 </Bucket>

task5/task5/task5.xcodeproj/xcuserdata/lilin.xcuserdatad/xcdebugger/Breakpoints_v2.xcbkptlist

@@ -207,18 +207,30 @@ Vector3f castRay(
                 // We also apply the lambert cosine law
                 // [/comment]
                 for (auto& light : scene.get_lights()) {
-                    Vector3f lightDir = light->position - hitPoint;
+                    Vector3f lightDir = light->position - hitPoint; // 光源和 hitPoint 的方向 // 后续判断阴影用
                     // square of the distance between hitPoint and the light
-                    float lightDistance2 = dotProduct(lightDir, lightDir);
+                    float lightDistance2 = dotProduct(lightDir, lightDir); // 光源和 hitPointd 的距离平方
                     lightDir = normalize(lightDir);
                     float LdotN = std::max(0.f, dotProduct(lightDir, N));
                     // is the point in shadow, and is the nearest occluding object closer to the object than the light itself?
+                    
+                    // 判断是否有阴影
+                    // 射线从碰撞点出发 方向是g光源
                     auto shadow_res = trace(shadowPointOrig, lightDir, scene.get_objects());
+                    
+                    // tNear 是射线出发后碰到的最近的物体的距离
+                    // 如果这个距离小于光源到碰撞点的距离 表示其中有物体挡住了光源  存在阴影
                     bool inShadow = shadow_res && (shadow_res->tNear * shadow_res->tNear < lightDistance2);
-
+                    
+                    // light->intensity * LdotN Lambert Cosine Law
                     lightAmt += inShadow ? 0 : light->intensity * LdotN;
+                    
+                    // 不要忘记负号
+                    // 在冯氏光照模型中 光的方向是指光源的方向 而不是光线的方向
                     Vector3f reflectionDirection = reflect(-lightDir, N);
-
+                    
+                    
+                    // 下面是计算specular 用的 Phong 高光模型
                     specularColor += powf(std::max(0.f, -dotProduct(reflectionDirection, dir)),
                         payload->hit_obj->specularExponent) * light->intensity;
                 }