Rasagar/Library/PackageCache/com.unity.render-pipelines.universal/Documentation~/render-graph-draw-objects-in-a-pass.md

uid
urp-render-graph-draw-objects-in-a-pass

Draw objects in a render pass

To draw objects in a custom render pass that uses the render graph system, use the RendererListHandle API to create a list of objects to draw.

Create a list of objects to draw

Follow these steps:

1. In your ScriptableRenderPass class, in the class you use for pass data, create a RendererListHandle field.

   For example:

   private class PassData
   {
       public RendererListHandle objectsToDraw;
   }
   

2. Create a RendererListParams object that contains the objects to draw, drawing settings, and culling data. For more information about the RenderListParams object, refer to Creating a simple render loop in a custom render pipeline.

   For a detailed example, refer to Example.

3. In the RecordRenderGraph method, use the CreateRendererList API to convert the RendererListParams object to a handle that the render graph system can use.

   For example:

   RenderListHandle rendererListHandle = renderGraph.CreateRendererList(rendererListParameters);
   

4. Set the RendererListHandle field in the pass data.

   For example:

   passData.objectsToDraw = rendererListHandle;
   

Draw the objects

After you set a RendererListHandle in the pass data, you can draw the objects in the list.

Follow these steps:

1. In the RecordRenderGraph method, tell the render graph system to use the list of objects, using the UseRendererList API.

   For example:

   builder.UseRendererList(passData.rendererListHandle);
   

2. Set the texture to draw the objects onto. Set both the color texture and the depth texture so URP renders the objects correctly.

   For example, the following tells URP to draw to the color texture and depth texture of the active camera texture.

   UniversalResourceData frameData = frameContext.Get<UniversalResourceData>();
   builder.SetRenderAttachment(frameData.activeColorTexture, 0);
   builder.SetRenderAttachmentDepth(frameData.activeDepthTexture, AccessFlags.Write);
   

3. In your SetRenderFunc method, draw the renderers using the DrawRendererList API.

   For example:

   context.cmd.DrawRendererList(passData.rendererListHandle);
   

Example

The following Scriptable Renderer Feature redraws the objects in the scene that have their Lightmode tag set to UniversalForward, using an override material.

After you add this Scriptable Reader Feature to the renderer, set the Material To Use parameter to any material.

using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;
using UnityEngine.Rendering.RenderGraphModule;
 
public class DrawObjectsWithOverrideMaterial : ScriptableRendererFeature
{

    DrawObjectsPass drawObjectsPass;
    public Material overrideMaterial;
 
    public override void Create()
    {
        // Create the render pass that draws the objects, and pass in the override material
        drawObjectsPass = new DrawObjectsPass(overrideMaterial);

        // Insert render passes after URP's post-processing render pass
        drawObjectsPass.renderPassEvent = RenderPassEvent.AfterRenderingPostProcessing;
    }
 
    public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
    {
        // Add the render pass to the URP rendering loop
        renderer.EnqueuePass(drawObjectsPass);
    }

    class DrawObjectsPass : ScriptableRenderPass
    {
        private Material materialToUse;

        public DrawObjectsPass(Material overrideMaterial)
        {
            // Set the pass's local copy of the override material 
            materialToUse = overrideMaterial;
        }
       
        private class PassData
        {
            // Create a field to store the list of objects to draw
            public RendererListHandle rendererListHandle;
        }
 
        public override void RecordRenderGraph(RenderGraph renderGraph, ContextContainer frameContext)
        {
            using (var builder = renderGraph.AddRasterRenderPass<PassData>("Redraw objects", out var passData))
            {
                // Get the data needed to create the list of objects to draw
                UniversalRenderingData renderingData = frameContext.Get<UniversalRenderingData>();
                UniversalCameraData cameraData = frameContext.Get<UniversalCameraData>();
                UniversalLightData lightData = frameContext.Get<UniversalLightData>();
                SortingCriteria sortFlags = cameraData.defaultOpaqueSortFlags;
                RenderQueueRange renderQueueRange = RenderQueueRange.opaque;
                FilteringSettings filterSettings = new FilteringSettings(renderQueueRange, ~0);

                // Redraw only objects that have their LightMode tag set to UniversalForward 
                ShaderTagId shadersToOverride = new ShaderTagId("UniversalForward");

                // Create drawing settings
                DrawingSettings drawSettings = RenderingUtils.CreateDrawingSettings(shadersToOverride, renderingData, cameraData, lightData, sortFlags);

                // Add the override material to the drawing settings
                drawSettings.overrideMaterial = materialToUse;

                // Create the list of objects to draw
                var rendererListParameters = new RendererListParams(renderingData.cullResults, drawSettings, filterSettings);

                // Convert the list to a list handle that the render graph system can use
                passData.rendererListHandle = renderGraph.CreateRendererList(rendererListParameters);
                
                // Set the render target as the color and depth textures of the active camera texture
                UniversalResourceData resourceData = frameContext.Get<UniversalResourceData>();
                builder.UseRendererList(passData.rendererListHandle);
                builder.SetRenderAttachment(resourceData.activeColorTexture, 0);
                builder.SetRenderAttachmentDepth(resourceData.activeDepthTexture, AccessFlags.Write);

                builder.SetRenderFunc((PassData data, RasterGraphContext context) => ExecutePass(data, context));
            }
        }

        static void ExecutePass(PassData data, RasterGraphContext context)
        {
            // Clear the render target to black
            context.cmd.ClearRenderTarget(true, true, Color.black);

            // Draw the objects in the list
            context.cmd.DrawRendererList(data.rendererListHandle);
        }

    }
 
}

For another example, refer to the example called RendererList in the render graph system URP package samples.

Additional resources

• Use textures
• Using frame data
• Scriptable Renderer Features