61 lines
3.4 KiB
Markdown
61 lines
3.4 KiB
Markdown
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# Use a texture in a render pass in SRP Core
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You can use the render graph system API to set a texture as an input or output for a custom render pass, so you can read from or write to it.
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## Set a texture as an input
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To set a texture as an input for a custom render pass, follow these steps:
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1. In your pass data, add a texture handle field to the data your pass uses.
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For example:
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``` lang-cs
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// Create the data your pass uses
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public class MyPassData
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{
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// Add a texture handle
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public TextureHandle textureToUse;
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}
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```
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2. Set the texture handle to the texture you want to use. For more information, refer to [Create a texture in the render graph system](render-graph-create-a-texture.md) or [Import a texture into the render graph system](render-graph-import-a-texture.md).
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3. Call the [`UseTexture`](https://docs.unity3d.com/Packages/com.unity.render-pipelines.core@17.0/api/UnityEngine.Rendering.RenderGraphModule.IBaseRenderGraphBuilder.html#UnityEngine_Rendering_RenderGraphModule_IBaseRenderGraphBuilder_UseTexture_UnityEngine_Rendering_RenderGraphModule_TextureHandle__UnityEngine_Rendering_RenderGraphModule_AccessFlags_) method to set the texture as an input.
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For example:
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``` lang-cs
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builder.UseTexture(passData.textureToUse, AccessFlags.Read);
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```
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In your `SetRenderFunc` method, you can now use the `TextureHandle` object in the pass data as an input for APIs.
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## Set a texture as the render target
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To set a texture as the output for APIs, use the [`SetRenderAttachment`](https://docs.unity3d.com/Packages/com.unity.render-pipelines.core@17.0/api/UnityEngine.Rendering.RenderGraphModule.IRasterRenderGraphBuilder.html#UnityEngine_Rendering_RenderGraphModule_IRasterRenderGraphBuilder_SetRenderAttachment_UnityEngine_Rendering_RenderGraphModule_TextureHandle_System_Int32_UnityEngine_Rendering_RenderGraphModule_AccessFlags_) method. The `SetRenderAttachment` method sets the texture as write-only by default.
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For example:
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```lang-cs
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builder.SetRenderAttachment(textureHandle, 0);
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```
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You don't need to add the texture to your pass data. The render graph system sets up the texture for you automatically before it executes the render pass.
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You can't use `UseTexture` and `SetRenderAttachment` on the same texture in a `AddRasterRenderPass` render pass. Refer to [Change the render target during a render pass](#change-the-render-target-during-a-pass) for more information.
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<a name="change-the-render-target-during-a-pass"></a>
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## Change the render target during a render pass
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You can't change which texture Unity writes to during a render graph system render pass.
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You can do either of the following instead:
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- Create a second custom render pass, and use `builder.SetRenderAttachment` during the second render pass to change the render target.
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- Use the `UnsafePass` API so you can use the `SetRenderTarget` API in the `SetRenderFunc` method. For more information, refer to [Use the CommandBuffer interface in a render graph](render-graph-unsafe-pass.md).
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You can use these methods to read from and write to the same texture, by first copying from the texture to a temporary texture you create, then copying back.
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If you blit between several textures with different properties, rendering might be slow because Unity can't merge the blits into a single native render pass. Use the `AddUnsafePass` API and the `SetRenderTarget()` method instead.
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