[Port] [2021.3] DOCG-7622 Remove UI screenshots from render objects example, make page more concise

Author: markg-unity

Packages/com.unity.render-pipelines.universal/Documentation~/Images/how-to-render-objects/rendobj-depth-greater-see-through.png

@@ -1,142 +1,65 @@
-# Example: How to create a custom rendering effect using the Render Objects Renderer Feature
+---
+uid: urp-how-to-custom-effect-render-objects
+---
 
-URP draws objects in the **DrawOpaqueObjects** and **DrawTransparentObjects** passes. You might need to draw objects at a different point in the frame rendering, or interpret and write rendering data (like depth and stencil) in alternate ways. The [Render Objects Renderer Feature](renderer-feature-render-objects.md) lets you do such customizations by letting you draw objects on a certain layer, at a certain time, with specific overrides.
+# Example of creating a custom rendering effect using a Render Objects Renderer Feature in URP
 
-The example on this page describes how to create a custom rendering effect with the Render Objects Renderer Feature.
+The [Render Objects Renderer Feature](renderer-feature-render-objects) lets you draw objects at a specific point in the frame rendering loop. You can interpret and write rendering data such as depth and stencil in different ways, or draw a set of GameObjects at a certain time.
 
-## Example overview
+The following example uses a Render Objects Renderer Feature to draw a GameObject in a different color if it's behind other GameObjects.
 
-The example on this page demonstrates how to implement the following effect:
+![A character created from 3 simple capsules for the body and arms. The character is red, but as it moves behind a wall, the hidden parts are rendered blue.](../Images/how-to-render-objects/character-goes-behind-object.gif)
 
-* There is a character in the Scene.
+First, create a GameObject and attach it to a new [layer](https://docs.unity3d.com/Manual/Layers.html).
 
-    ![Character](../Images/how-to-render-objects/character.png)
+1. Create a GameObject in your scene.
+1. In the **Inspector** window, open the **Layer** dropdown and add a new layer. You can call the layer **DrawBehind**.
+1. Set the GameObject to the new layer.
 
-* When the character goes behind GameObjects, Unity draws the character silhouette with a different Material.
+Next, create a Render Objects Renderer Feature that renders only the new layer, on top of the scene.
 
-    ![Character goes behind GameObjects](../Images/how-to-render-objects/character-goes-behind-object.gif)
+1. In the **Project** window, select the [URP Renderer asset](../universalrp-asset) your project uses, for example **Settings** > **PC_Renderer**.
+1. To create a Render Objects Renderer Feature, select **Add Renderer Feature** in the **Inspector** window, then select **Render Objects**.
+1. To make the Renderer Feature draw only the layer with the GameObject, open the **Render Objects (Render Objects)** dropdown, then set **Layer Mask** to the layer.
+1. Set **Event** to the **AfterRenderingOpaques** injection point. For more information about custom pass injection points, refer to [Custom Pass injection points](../customize/custom-pass-injection-points).
 
-## Prerequisites
+Next, adjust the Renderer Feature so it renders only the parts hidden behind other GameObjects, and in a different color.
 
-This example requires the following:
+1. Open the **Overrides** dropdown, then select **Depth** and set **Depth Test** to **Greater**.
 
-* A Unity project with the URP package installed.
+    The Renderer Feature now only renders a pixel if its depth is greater than the current pixel in the depth buffer, which means the new pixel is behind another GameObject.
 
-* The **Scriptable Render Pipeline Settings** property refers to a URP asset (**Project Settings** > **Graphics** > **Scriptable Render Pipeline Settings**).
+1. [Create a new material](../shaders-in-universalrp) that uses the **Universal Render Pipeline/Unlit** shader.
+1. Set the **Base Map** color to a color of your choice.
+1. In the Renderer Feature, in the **Overrides** section, set **Material** to the material you created.
 
-## Create example Scene and GameObjects<a name="example-objects"></a>
+When you move the GameObject behind other GameObjects, Unity now renders the hidden parts in the color you selected.
 
-To follow the steps in this example, create a new Scene with the following GameObjects:
+![The red characters moves behind a wall. Unity renders the hidden parts using a blue material.](../Images/how-to-render-objects/character-depth-test-greater.gif)
 
-1. Create a Cube. Set its **Scale** values so that it looks like a wall.
+## Fix overlapping areas of a GameObject
 
-    ![Cube that represents a wall](../Images/how-to-render-objects/rendobj-cube-wall.png)
+If you use a complex GameObject, the Renderer Feature might draw overlapping parts as though they're hidden. This is because the depth of one part is greater than the overlapping part.
 
-2. Create a Material and assign it the `Universal Render Pipeline/Lit` shader. Select the base color (for example, red). Call the Material `Character`.
+![A capsule with a smaller capsule attached. The Renderer Feature renders part of the larger capsule using the blue material, because it's behind the smaller part.](../Images/how-to-render-objects/rendobj-depth-greater-see-through.png)
 
-3. Create a basic character and assign it the Character Material. In this example, the character consists of three capsules: the big capsule in the center represents the body, and the two smaller capsules represent the hands.
+To fix this issue, disable rendering the whole GameObject, and create a new Renderer Feature that renders the non-hidden parts. Follow these steps:
 
-    ![The character consisting of three capsules](../Images/how-to-render-objects/character-views-side-top-persp.png)
+1. In the URP Renderer asset, open the **Opaque Layer Mask** dropdown and disable the layer you added. 
 
-    To make it easier to manipulate the character in the Scene, add the three Capsules as child GameObjects under the Character GameObject.
+    Unity now doesn't draw the layer in the opaque render pass. The Renderer Feature still draws the hidden parts, because it's in a different render pass.
 
-    ![Character objects in Hierarchy](../Images/how-to-render-objects/character-in-hierarchy.png)
+    ![Unity does not draw the character unless it's behind an object](../Images/how-to-render-objects/rendobj-character-only-behind.png)
 
-4. Create a Material and assign it the `Universal Render Pipeline/Unlit` shader. Select the base color that you would like the character to have when it's behind GameObjects (for example, blue). Call the Material `CharacterBehindObjects`.
+1. Add a new Render Objects Renderer Feature.
+1. Set **Layer Mask** to the new layer, so this Renderer Feature draws the GameObject.
+1. Set **Event** to the **AfterRenderingOpaques** injection point.
+1. To avoid the first Renderer Feature affecting the depth calculations in the new Renderer Feature, disable **Write Depth** in the **Overrides** section of the first Renderer Feature.
 
-Now you have the setup necessary to follow the steps in this example.
+The first Renderer Feature draws the hidden parts, and the second Renderer Feature draws the rest of the GameObject.
 
-## Example implementation
+![A character created from 3 simple capsules for the body and arms. The character is red, but as it moves behind a wall, the hidden parts are rendered blue.](../Images/how-to-render-objects/character-goes-behind-object.gif)
 
-This section assumes that you created a Scene as described in section [Example Scene and GameObjects](#example-objects).
+## Additional resources
 
-The example implementation uses two Render Objects Renderer Features: one to draw parts of the character that are behind other GameObjects, and another one to draw the parts of the character that are in front of other GameObjects.
-
-### Create a Renderer Feature to draw the character behind GameObjects
-
-Follow these steps to create a Renderer Feature to draw the character behind GameObjects.
-
-1. Select a URP Renderer.
-
-    ![Select a URP Renderer](../Images/how-to-render-objects/rendobj-select-urp-renderer.png)
-
-2. In the Inspector, click **Add Renderer Feature** and select **Render Objects**.
-
-    ![Add Render Object Renderer Feature](../Images/how-to-render-objects/rendobj-add-rend-obj.png)
-
-    Select the **Name** field and enter the name of the new Renderer Feature, for example, **DrawCharacterBehind**.
-
-3. This example uses Layers to filter the GameObjects to render. Create a new Layer and call it **Character**.
-
-    ![Create new Layer called Character](../Images/how-to-render-objects/rendobj-new-layer-character.png)
-
-4. Select the **Character** GameObject and assign it to the `Character` Layer. To do this, open the Layer drop down and select `Character`.
-    ![Assign Character GameObject to Character Layer](../Images/how-to-render-objects/rendobj-assign-character-gameobject-layer.png)
-
-5. In the `DrawCharacterBehind` Renderer Feature, in **Filters** > **Layer Mask**, select `Character`. With this setting, this Renderer Feature renders GameObjects only in the Layer `Character`.
-
-6. In **Overrides** > **Material**, select the `CharacterBehindObjects` Material.
-
-    The Renderer Feature overrides the Material of a GameObject with the selected Material.
-
-    ![Layer Mask, Material Override](../Images/how-to-render-objects/rendobj-change-layer-override-material.png)
-
-7. The intended behavior is that the Renderer Feature renders the character with the `CharacterBehindObjects` Material only when the character is behind other GameObjects.
-
-    To achieve this, select the **Depth** check box, and set the **Depth Test** property to **Greater**.
-
-    ![Set Depth Test to Greater](../Images/how-to-render-objects/rendobj-depth-greater.png)
-
-With these settings, Unity renders the character with the `CharacterBehindObjects` Material only when the character is behind another GameObject. However, Unity also renders parts of the character using the `CharacterBehindObjects` Material, because some parts of the character occlude the character itself.
-
-![Unity renders parts of the character using the `CharacterBehindObjects` Material](../Images/how-to-render-objects/character-depth-test-greater.gif)
-
-### Create an extra Renderer Feature to avoid the self see-through effect
-
-The settings in the previous section result in the self see-through effect for the following reason:
-
-* When performing the Opaque rendering pass of the URP Renderer, Unity renders all GameObjects belonging to the character with the `Character` Material and writes depth values to the Depth buffer. This happens before Unity starts executing the `DrawCharacterBehind` Renderer Feature, because, by default, new Render Objects Renderer Features have the value **AfterRenderingOpaques** in the **Event** property.
-
-    The **Event** property defines the injection point where Unity injects Render Passes from the Render Objects Renderer Feature. The event when URP Renderer draws GameObjects in the **Opaque Layer Mask** is the **BeforeRenderingOpaques** event.
-
-* When executing the `DrawCharacterBehind` Renderer Feature, Unity performs the depth test using the condition specified in the **Depth Test** property. In the following screenshot, a bigger capsule occludes part of the smaller capsule, and the depth test passes for that part of the smaller capsule. The Renderer Feature overrides the Material for that part.
-
-    ![Self see-through effect](../Images/how-to-render-objects/rendobj-depth-greater-see-through.png)
-
-The following steps describe how to avoid such behavior and ensure that Unity draws all parts of the character with proper Materials.
-
-1. In the URP asset, in **Filtering** > **Opaque Layer Mask**, clear the check mark next to the `Character` Layer.
-
-    ![Clear the check mark next to the `Character` Layer](../Images/how-to-render-objects/rendobj-in-urp-asset-clear-character.png)
-
-    Now Unity does not render the character unless it's behind a GameObject.
-
-    ![Unity does not render the character unless it's behind an object](../Images/how-to-render-objects/rendobj-character-only-behind.png)
-
-2. Add a new Render Objects Renderer Feature, and call it `Character`.
-
-3. In the `Character` Renderer Feature, in **Filters** > **Layer Mask**, select the `Character` Layer.
-
-    ![Set Layer Mask Filter to Character Layer](../Images/how-to-render-objects/rendobj-render-objects-character.png)
-
-    Now Unity renders the character with the `Character` Material even when the character is behind GameObjects.
-
-    This happens because the `DrawCharacterBehind` Renderer Feature writes values to the depth buffer. When Unity executes the `Character` Renderer Feature, the pixels on the character appear to be in front of the pixels that Unity has drawn previously, and Unity draws on top of those pixels.
-
-4. In the `DrawCharacterBehind` Renderer Feature, In **Overrides** > **Depth**, clear the **Write Depth** check box. With this setting, the `DrawCharacterBehind` Renderer Feature does not make changes to the depth buffer and the `Character` Renderer Feature does not draw the character when it's behind GameObjects.
-
-    ![Clear Write Depth](../Images/how-to-render-objects/rendobj-render-objects-no-write-depth.png)
-
-The example is complete. When the character goes behind GameObjects, Unity draws the character silhouette with the `CharacterBehindObjects` Material.
-
-![Character goes behind objects](../Images/how-to-render-objects/character-goes-behind-object.gif)
-
-With the extra `Character` Renderer Feature, Unity renders GameObjects as follows:
-
-1. URP Renderer does not render the `Character` GameObject in the **BeforeRenderingOpaques** event, because the `Character` Layer is excluded from the **Opaque Layer Mask** list.
-
-2. The `DrawCharacterBehind` Renderer Feature draws parts of the character that are behind other GameObjects. This happens in the **AfterRenderingOpaques** event.
-
-3. The `Character` Renderer Feature draws parts of the character that are in front of other GameObjects. This happens in the **AfterRenderingOpaques** event, and after executing the `DrawCharacterBehind` Renderer Feature.
-
-To see another use case of the Render Objects Renderer Feature, refer to the **Object Occlusion** Scene in the [Universal Rendering Examples](https://github.com/Unity-Technologies/UniversalRenderingExamples) project.
+- [Renderer Objects Renderer Feature reference](renderer-feature-render-objects)