highlights for 08

Author: cdhanna

articles/tutorials/advanced/2d_shaders/08_light_effect/index.md

@@ -430,23 +430,23 @@ When each individual light is drawn into the `LightBuffer`, it needs to use the
 
    Create a new struct in the `pointLightEffect.fx` file:
 
-[!code-hlsl[](./snippets/snippet-8-57.hlsl)]
+[!code-hlsl[](./snippets/snippet-8-57.hlsl?highlight=6)]
 
 6. Then, create a new vertex function that uses the new `LightVertexShaderOutput`. This function will call to the existing `MainVS` function that does the 3d effect, and add the screen coordinates afterwards:
 
 [!code-hlsl[](./snippets/snippet-8-58.hlsl)]
 
 7. Make sure to update the `technique` to use the new vertex function:
 
-[!code-hlsl[](./snippets/snippet-8-59.hlsl)]
+[!code-hlsl[](./snippets/snippet-8-59.hlsl?highlight=5)]
 
 8. In the pixel function, to visualize the screen coordinates, we will short-circuit the existing light code and just render out the screen coordinates. First, modify the input of the pixel function to be the `LightVertexShaderOutput` struct that was returned from the `LightVS` vertex function:
 
 [!code-hlsl[](./snippets/snippet-8-60.hlsl)]
 
 9. And make the function immediately return the screen coordinates in the red and green channel:
 
-[!code-hlsl[](./snippets/snippet-8-61.hlsl)]
+[!code-hlsl[](./snippets/snippet-8-61.hlsl?highlight=3)]
 
 10. Be careful, if you run the game now, it will not look right. We need to make sure to send the `MatrixTransform` parameter from C# as well. In the `GameScene`'s `Update()` method, make sure to pass the `MatrixTransform` to _both_ the `_gameMaterial` _and_ the `Core.PointLightMaterial`. 
 
@@ -500,9 +500,12 @@ Now it is time to _use_ the normal data in conjunction with the light direction
 
 [!code-hlsl[](./snippets/snippet-8-65.hlsl)]
 
+> [!note]
+> The `normalDir`, `lightDir`, and [`dot`](https://learn.microsoft.com/en-us/windows/win32/direct3dhlsl/dx-graphics-hlsl-dot) product are a simplified version of the [Blinn-Phong shading model](https://en.wikipedia.org/wiki/Blinn%E2%80%93Phong_reflection_model). 
+
 2. And then make the final color use the `lightAmount`:
 
-[!code-hlsl[](./snippets/snippet-8-66.hlsl)]
+[!code-hlsl[](./snippets/snippet-8-66.hlsl?highlight=7)]
 
 | ![Figure 8-22: The light with the normal](./images/light-with-normal.png) |
 | :-----------------------------------------------------------------------: |

articles/tutorials/advanced/2d_shaders/08_light_effect/snippets/snippet-8-53.cs

@@ -1,4 +1,6 @@
-public static void Draw(SpriteBatch spriteBatch, List<PointLight> pointLights, Texture2D normalBuffer)  
-{  
+public static void Draw(SpriteBatch spriteBatch, List<PointLight> pointLights, Texture2D normalBuffer)
+{
     Core.PointLightMaterial.SetParameter("NormalBuffer", normalBuffer);
     // ...
+
+}

articles/tutorials/advanced/2d_shaders/08_light_effect/snippets/snippet-8-54.cs

@@ -1,3 +1,10 @@
-// start rendering the lights  
-_deferredRenderer.StartLightPhase();  
-PointLight.Draw(Core.SpriteBatch, _lights, _deferredRenderer.NormalBuffer);
+public override void Draw(GameTime gameTime)
+{
+    // ...
+
+    // start rendering the lights  
+    _deferredRenderer.StartLightPhase();
+    PointLight.Draw(Core.SpriteBatch, _lights, _deferredRenderer.NormalBuffer);
+
+    // ...
+}

articles/tutorials/advanced/2d_shaders/08_light_effect/snippets/snippet-8-60.hlsl

@@ -1 +1,4 @@
 float4 MainPS(LightVertexShaderOutput input) : COLOR
+{
+    // ...
+}

articles/tutorials/advanced/2d_shaders/08_light_effect/snippets/snippet-8-61.hlsl

@@ -1 +1,4 @@
-return float4(input.ScreenCoordinates.xy, 0, 1);
+float4 MainPS(LightVertexShaderOutput input) : COLOR
+{
+    return float4(input.ScreenCoordinates.xy, 0, 1);
+}

articles/tutorials/advanced/2d_shaders/08_light_effect/snippets/snippet-8-65.hlsl

@@ -1,10 +1,17 @@
-float4 normal = tex2D(NormalBufferSampler,input.ScreenCoordinates);  
-  
-// convert from [0,1] to [-1,1]  
-float3 normalDir = (normal.xyz-.5)*2;  
-  
-// find the direction the light is travelling at the current pixel  
-float3 lightDir = float3( normalize(input.TextureCoordinates - .5), 1);  
-  
-// how much is the normal direction pointing towards the light direction?  
-float lightAmount = saturate(dot(normalDir, lightDir));
+float4 MainPS(LightVertexShaderOutput input) : COLOR
+{
+    // ...
+    
+    float4 normal = tex2D(NormalBufferSampler,input.ScreenCoordinates);  
+    
+    // convert from [0,1] to [-1,1]  
+    float3 normalDir = (normal.xyz-.5)*2;  
+    
+    // find the direction the light is travelling at the current pixel  
+    float3 lightDir = float3( normalize(input.TextureCoordinates - .5), 1);  
+    
+    // how much is the normal direction pointing towards the light direction?  
+    float lightAmount = saturate(dot(normalDir, lightDir));
+
+    // ...
+}

articles/tutorials/advanced/2d_shaders/08_light_effect/snippets/snippet-8-66.hlsl

@@ -1 +1,9 @@
-color.a *= falloff * lightAmount;
+
+float4 MainPS(LightVertexShaderOutput input) : COLOR
+{
+    // ...
+    
+    float4 color = input.Color;
+    color.a *= falloff * lightAmount;
+    return color;
+}

articles/tutorials/advanced/2d_shaders/08_light_effect/snippets/snippet-8-69.cs

@@ -1,2 +1,7 @@
-// Move some lights around for artistic effect  
-MoveLightsAround(gameTime);
+public override void Update(GameTime gameTime)
+{
+    // ...
+    
+    // Move some lights around for artistic effect  
+    MoveLightsAround(gameTime);
+}