CommandBuffer.BuildRayTracingAccelerationStructure

Добавляет команду для построения RayTracingAccelerationStructure для использования в отправке трассирования лучей или при использовании встроенного трассирования лучей (запросы на лучи).

Чтобы убедиться, что структура ускорения обновлена, вызовите этот метод перед использованием структуры ускорения в шейдерах с трассированием лучей (например, перед вызовом CommandBuffer.DispatchRays) или при использовании встроенного трассирования лучей. В следующем примере метод PositionRandomInstances использует отправку вычисления шейдера для изменения позиций экземпляров сетки в мировом пространстве, после чего RayTracingAccelerationStructure восстанавливается.

using UnityEngine;
using UnityEngine.Rendering;

public class RayTracingInstanceManager : MonoBehaviour
{
    public Mesh instanceMesh;
    public Material instanceMaterial;
    public int maxInstanceCount = 1024;

    public Vector3 spawnBounds = new Vector3(10f, 0f, 10f);
    public ComputeShader positioningShader;
    public RayTracingShader rayTracingShader;

    private RayTracingAccelerationStructure rtas;
    private GraphicsBuffer instanceBuffer;
    private GraphicsBuffer countBuffer;
    private CommandBuffer cmd;
    private RenderTexture rayTracingOutput;
    private uint cameraWidth = 0;
    private uint cameraHeight = 0;

    void Start()
    {
        InitializeRayTracing();
        UpdateRaytracingWorld();
    }

    void InitializeRayTracing()
    {
        // Create command buffer
        cmd = new CommandBuffer();
        cmd.name = "Ray Tracing Indirect Setup";

        // Set up acceleration structure
        var settings = new RayTracingAccelerationStructure.Settings
        {
            managementMode = RayTracingAccelerationStructure.ManagementMode.Manual,
            layerMask = -1
        };
        rtas = new RayTracingAccelerationStructure(settings);

        // Create buffers
        instanceBuffer = new GraphicsBuffer(
            GraphicsBuffer.Target.Structured,
            maxInstanceCount,
            System.Runtime.InteropServices.Marshal.SizeOf(typeof(Matrix4x4))
        );

        countBuffer = new GraphicsBuffer(
            GraphicsBuffer.Target.IndirectArguments,
            1,
            sizeof(int)
        );
    }

    void CreateResources()
    {
        if (cameraWidth != Camera.main.pixelWidth || cameraHeight != Camera.main.pixelHeight)
        {
            if (rayTracingOutput != null)
                rayTracingOutput.Release();

            rayTracingOutput = new RenderTexture(Camera.main.pixelWidth, Camera.main.pixelHeight, 0, RenderTextureFormat.ARGBHalf);
            rayTracingOutput.enableRandomWrite = true;
            rayTracingOutput.Create();

            cameraWidth = (uint)Camera.main.pixelWidth;
            cameraHeight = (uint)Camera.main.pixelHeight;
        }
   }

    void PositionRandomInstances()
    {
        if (positioningShader == null)
        {
            Debug.LogError("Error: Compute shader is missing. Assign a compute shader to the positioningShader property.");
            return;
        }

        // Add instances indirectly
        RayTracingMeshInstanceConfig meshConfig = new RayTracingMeshInstanceConfig();
        meshConfig.mesh = instanceMesh;
        meshConfig.material = instanceMaterial;
        meshConfig.enableTriangleCulling = false;
        meshConfig.lightProbeUsage = LightProbeUsage.Off;
        meshConfig.layer = -1;

        rtas.AddInstancesIndirect(meshConfig, instanceBuffer, maxInstanceCount, countBuffer, 0);

        // Upload data to buffers
        cmd.SetBufferData(countBuffer, new int[] { 0, maxInstanceCount });

        // Generate random instance positions on GPU using a compute shader.
        cmd.SetComputeVectorParam(positioningShader, "SpawnBounds", spawnBounds);
        cmd.SetComputeBufferParam(positioningShader, 0, "InstanceMatrices", instanceBuffer);
        cmd.SetComputeIntParam(positioningShader, "TotalInstanceCount", maxInstanceCount);

        int threadGroups = (maxInstanceCount + 64 - 1) / 64;
        cmd.DispatchCompute(positioningShader, 0, threadGroups, 1, 1);
    }

    void UpdateRaytracingWorld()
    {
        if (instanceMesh == null || instanceMaterial == null)
        {
            Debug.LogError("Error: Mesh or material is missing. Assign a mesh to the instanceMesh property and a material to the instanceMaterial property.");
            return;
        }

        // Clear previous instances
        rtas.ClearInstances();

        PositionRandomInstances();

        // Build acceleration structure from the indirect instances.
        cmd.BuildRayTracingAccelerationStructure(rtas);

        // The command buffer will be executed in the next OnRenderImage
    }

    void Update()
    {
        // Example: Update structure when space is pressed
        if (Input.GetKeyDown(KeyCode.Space))
        {
            UpdateRaytracingWorld();
        }
    }

    [ImageEffectOpaque]
    void OnRenderImage(RenderTexture src, RenderTexture dest)
    {
        if (!SystemInfo.supportsRayTracing || !rayTracingShader)
        {
            Debug.LogWarning("Warning: The Ray Tracing API is not supported by this GPU or by the current graphics API.");
            Graphics.Blit(src, dest);
            return;
        }

        CreateResources();

        cmd.SetRayTracingShaderPass(rayTracingShader, "Test");

        // Input
        cmd.SetRayTracingAccelerationStructure(rayTracingShader, Shader.PropertyToID("g_AccelStruct"), rtas);
        cmd.SetRayTracingMatrixParam(rayTracingShader, Shader.PropertyToID("g_InvViewMatrix"), Camera.main.cameraToWorldMatrix);
        cmd.SetGlobalVector(Shader.PropertyToID("g_CameraPos"), Camera.main.transform.position);

        // Output
        cmd.SetRayTracingTextureParam(rayTracingShader, Shader.PropertyToID("g_Output"), rayTracingOutput);

        // Execute the raytracing shader
        cmd.DispatchRays(rayTracingShader, "MainRayGenShader", cameraWidth, cameraHeight, 1);

        // Execute command buffer
        Graphics.ExecuteCommandBuffer(cmd);
        cmd.Clear();

        Graphics.Blit(rayTracingOutput, dest);
    }

    void OnDisable()
    {
        // Cleanup
        if (instanceBuffer != null)
        {
            instanceBuffer.Release();
            instanceBuffer = null;
        }

        if (countBuffer != null)
        {
            countBuffer.Release();
            countBuffer = null;
        }

        if (rtas != null)
        {
            rtas.Dispose();
            rtas = null;
        }

        if (cmd != null)
        {
            cmd.Release();
            cmd = null;
        }

        if (rayTracingOutput != null)
        {
            rayTracingOutput.Release();
            rayTracingOutput = null;
        }
    }
}

Дополнительные ресурсы: ,SetRayTracingAccelerationStructure,, ,SetGlobalRayTracingAccelerationStructure,, ,DispatchRays,, ,RayTracingAccelerationStructure.Build,.