Version: Unity 6 (6000.0)
Language : English
Run a compute shader in a render pass in URP
Analyze a render graph in URP

Create input data for a compute shader in URP

When you run a compute shader in a render pass, you can allocate a buffer to provide input data for the compute shaderA program that runs on the GPU. More info
See in Glossary
.

Follow these steps:

  1. Create a graphics buffer, then add a handle to it in your pass data. For example:

    // Declare an input buffer
    public GraphicsBuffer inputBuffer;
    
    // Add a handle to the input buffer in your pass data
    class PassData
    {
        ...
        public BufferHandle input;
    }
    
    // Create the buffer in the render pass constructor
    public ComputePass(ComputeShader computeShader)
    {
        // Create the input buffer as a structured buffer
        // Create the buffer with a length of 5 integers, so you can input 5 values.
        inputBuffer = new GraphicsBuffer(GraphicsBuffer.Target.Structured, 5, sizeof(int));
    }
    
  2. Set the data in the buffer. For example:

    var inputValues = new List<int> { 1, 2, 3, 4, 5 };
    inputBuffer.SetData(inputValues);
    
  3. Use the ImportBuffer render graph API to convert the buffer to a handle the render graph system can use, then set the BufferHandle field in the pass data. For example:

    BufferHandle inputHandleRG = renderGraph.ImportBuffer(inputBuffer);
    passData.input = inputHandleRG;
    
  4. Use the UseBuffer method to set the buffer as a readable buffer in the render graph system. For example:

    builder.UseBuffer(passData.input, AccessFlags.Read);
    
  5. In your SetRenderFunc method, use the SetComputeBufferParam API to attach the buffer to the compute shader. For example:

    // The first parameter is the compute shader
    // The second parameter is the function that uses the buffer
    // The third parameter is the RWStructuredBuffer input variable to attach the buffer to
    // The fourth parameter is the handle to the input buffer
    context.cmd.SetComputeBufferParam(passData.computeShader, passData.computeShader.FindKernel("Main"), "inputData", passData.input);
    

Example

For a full example, refer to the example called Compute in the Universal Render Pipeline (URP) package samples.

Additional resources

Run a compute shader in a render pass in URP
Analyze a render graph in URP