59 lines
3.9 KiB
Markdown
59 lines
3.9 KiB
Markdown
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# Blit using the render graph system in SRP Core
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To blit from one texture to another in the render graph system, use the [`AddBlitPass`](https://docs.unity3d.com/Packages/com.unity.render-pipelines.core@17.3/api/UnityEngine.Rendering.RenderGraphModule.Util.RenderGraphUtils.html#UnityEngine_Rendering_RenderGraphModule_Util_RenderGraphUtils_AddBlitPass_UnityEngine_Rendering_RenderGraphModule_RenderGraph_UnityEngine_Rendering_RenderGraphModule_Util_RenderGraphUtils_BlitMaterialParameters_System_String_System_Boolean_) API. The API generates a render pass automatically, so you don't need to use a method like `AddRasterRenderPass`.
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Follow these steps:
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1. To create a shader and material that works with a blit render pass, from the main menu select **Assets** > **Create** > **Shader** > **SRP Blit Shader**, then create a material from it.
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1. Add `using UnityEngine.Rendering.RenderGraphModule.Util` to your render pass script.
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1. In your render pass, create a field for the blit material. For example:
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```lang-cs
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public class MyBlitPass : ScriptableRenderPass
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{
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Material blitMaterial;
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}
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```
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1. Set up the texture to blit from and blit to. For example:
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```lang-cs
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TextureHandle sourceTexture = renderGraph.CreateTexture(sourceTextureProperties);
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TextureHandle destinationTexture = renderGraph.CreateTexture(destinationTextureProperties);
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```
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1. To set up the material, textures, and shader pass for the blit operation, create a [`RenderGraphUtils.BlitMaterialParameters`](https://docs.unity3d.com/Packages/com.unity.render-pipelines.core@17.3/api/UnityEngine.Rendering.RenderGraphModule.Util.RenderGraphUtils.BlitMaterialParameters.html) object. For example:
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```lang-cs
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// Create a BlitMaterialParameters object with the blit material, source texture, destination texture, and shader pass to use.
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var blitParams = new RenderGraphUtils.BlitMaterialParameters(sourceTexture, destinationTexture, blitMaterial, 0);
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```
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1. To add a blit pass, call the [`AddBlitPass`](https://docs.unity3d.com/Packages/com.unity.render-pipelines.core@17.3/api/UnityEngine.Rendering.RenderGraphModule.Util.RenderGraphUtils.html#UnityEngine_Rendering_RenderGraphModule_Util_RenderGraphUtils_AddBlitPass_UnityEngine_Rendering_RenderGraphModule_RenderGraph_UnityEngine_Rendering_RenderGraphModule_Util_RenderGraphUtils_BlitMaterialParameters_System_String_System_Boolean_) method with the blit parameters. For example:
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```lang-cs
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renderGraph.AddBlitPass(blitParams, "Pass created with AddBlitPass");
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```
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If you use `AddBlitPass` with a default material, Unity might use the `AddCopyPass` API instead, to optimize the render pass so it accesses the framebuffer from the on-chip memory of the GPU instead of video memory. This process is sometimes called framebuffer fetch. For more information, refer to [`AddCopyPass`](https://docs.unity3d.com/Packages/com.unity.render-pipelines.core@17.3/api/UnityEngine.Rendering.RenderGraphModule.Util.RenderGraphUtils.html#UnityEngine_Rendering_RenderGraphModule_Util_RenderGraphUtils_AddCopyPass_UnityEngine_Rendering_RenderGraphModule_RenderGraph_UnityEngine_Rendering_RenderGraphModule_TextureHandle_UnityEngine_Rendering_RenderGraphModule_TextureHandle_System_String_System_Boolean_) API.
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## Customize the render pass
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To customize the render pass that the methods generate, for example to change settings or add more resources, call the APIs with the `returnBuilder` parameter set to `true`. The APIs then return the `IBaseRenderGraphBuilder` object that you usually receive as `var builder` from a method like `AddRasterRenderPass`.
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For example:
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```lang-cs
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using (var builder = renderGraph.AddBlitPass(blitParams, "Pass created with AddBlitPass", returnBuilder: true))
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{
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// Use the builder variable to customize the render pass here.
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}
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```
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## Additional resources
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- [The RTHandle System](rthandle-system.md)
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- [Shaders](shaders.md)
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