# Use a texture in a render pass in SRP Core

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.

## Set a texture as an input

To set a texture as an input for a custom render pass, follow these steps:

1. In your pass data, add a texture handle field to the data your pass uses.

    For example:

    ``` lang-cs
    // Create the data your pass uses
    public class MyPassData
    {
        // Add a texture handle
        public TextureHandle textureToUse;
    }
    ```

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).

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.

    For example:

    ``` lang-cs
    builder.UseTexture(passData.textureToUse, AccessFlags.Read);
    ```

In your `SetRenderFunc` method, you can now use the `TextureHandle` object in the pass data as an input for APIs. 

## Set a texture as the render target

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.

For example:

```lang-cs
builder.SetRenderAttachment(textureHandle, 0);
```

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.

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.

<a name="change-the-render-target-during-a-pass"></a>
## Change the render target during a render pass

You can't change which texture Unity writes to during a render graph system render pass.

You can do either of the following instead:

- Create a second custom render pass, and use `builder.SetRenderAttachment` during the second render pass to change the render target.
- 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).

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.

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.