DOCG-7438 Improve Emission node docs

Author: markg-unity

Packages/com.unity.shadergraph/Documentation~/Emission-Node.md

@@ -1,30 +1,42 @@
-# Emission Node
+# Emission node
 
-The Emission Node allows you to apply emission in your Shader Graph.
+The Emission node outputs a color that makes a material appear as a visible source of light.
 
 ## Render pipeline compatibility
 
-| **Node** | **Universal Render Pipeline (URP)** | **High Definition Render Pipeline (HDRP)** |
-| -------- | ----------------------------------- | ------------------------------------------ |
-| Emission | No                                  | Yes                                        |
+The Emission node is compatible only with the High Definition Render Pipeline (HDRP).
 
 ## Ports
 
-| Name          | Direction | Type           | Description                                                  |
-| :------------ | :-------- | :------------- | :----------------------------------------------------------- |
-| **color**     | Input     | LDR Color(RGB) | Sets the low dynamic range (LDR) color of the emission.      |
-| **intensity** | Input     | Float          | Sets the intensity of the emission color.                    |
-| **output**    | Output    | HDR Color(RGB) | Outputs the high dynamic range (HDR) color that this Node produces. |
+| **Name** | **Direction** | **Type** | **Description** |
+|-|-|-|-|
+| **Color** | Input | Low dynamic range (LDR) RGB color | Sets the low dynamic range (LDR) color to make emissive. |
+| **Intensity** | Input | Float | Sets the intensity of the emission of the output color. |
+| **Exposure Weight** | Input | Float | Sets how much the [exposure](https://docs.unity3d.com/Packages/com.unity.render-pipelines.high-definition@latest/index.html?subfolder=/manual/Override-Exposure.html) of the scene affects emission. The range is between 0 and 1. A value of 0 means that exposure does not affect this part of the emission. A value of 1 means that exposure fully affects this part of the emission. |
+| **Output** | Output | High dynamic range (HDR) RGB color | The emissive color.  |
 
-## Notes
+## Properties
 
-### Emission Unit
+| **Name** | **Description** |
+|-|-|
+| **Intensity Unit** | Sets the unit of the **Intensity** property. For more information, refer to [Understand physical light units](https://docs.unity3d.com/Packages/com.unity.render-pipelines.high-definition@latest/index.html?subfolder=/manual/Physical-Light-Units.html). The options are: <ul><li>**Nits**: Sets the units as nits, which is a measure of luminance, the surface power of a light source.</li><li>**EV100**: Sets the units as EV<sub>100</sub>, which is a measure of exposure value.</li></ul> |
+| **Normalize Color** | Adjusts the intensity of the input color so the red, green, and blue values look similar. As a result, colors are more balanced in the **Output**. |
 
-You can use two [physical light units](https://docs.unity3d.com/Packages/com.unity.render-pipelines.high-definition@latest/index.html?subfolder=/manual/Physical-Light-Units.html) to control the strength of the emission:
+## Generated code example
 
-* [Nits](https://docs.unity3d.com/Packages/com.unity.render-pipelines.high-definition@latest/index.html?subfolder=/manual/Physical-Light-Units.html%23Nits).
-* [EV<sub>100</sub>](https://docs.unity3d.com/Packages/com.unity.render-pipelines.high-definition@latest/index.html?subfolder=/manual/Physical-Light-Units.html%23EV).
+```hlsl
+float3 Unity_HDRP_GetEmissionHDRColor_float(float3 ldrColor, float luminanceIntensity, float exposureWeight)
+{
+    // Convert the LDR color. This line is generated only if Normalize Color is enabled.
+    ldrColor = ldrColor * rcp(max(Luminance(ldrColor), 1e-6));
 
+    float3 hdrColor = ldrColor * luminanceIntensity;
+    float inverseExposureMultiplier = GetInverseCurrentExposureMultiplier();
+    hdrColor = lerp(hdrColor * inverseExposureMultiplier, hdrColor, exposureWeight);
+    return hdrColor;
+}
+```
 
-### Exposure Weight
-You can use Exposure Weight to determine how exposure affects emission. It is a value between **0** and **1** where. A value of **0** means that exposure does not effect this part of the emission. A value of **1** means that exposure fully affects this part of the emission.
+## Additional resources
+
+- [Add light emission to a material](https://docs.unity3d.com/Manual/StandardShaderMaterialParameterEmission.html)