init commit

Assets/Scripts/Lesson_1/GPUGrassInstancing.cs

@@ -0,0 +1,65 @@
+using UnityEngine;
+using UnityEngine.Rendering;
+
+public class GPUGrassRenderer : MonoBehaviour
+{
+    public Mesh grassMesh;            // îäíà ìîäåëü òðàâèíêè (îäèí submesh)
+    public Material grassMaterial;    // shader ìຠï³äòðèìóâàòè GPU instancing
+    public ComputeShader computeShader;
+
+    public int countX = 256;
+    public int countZ = 256;
+    public float sizeX = 50f;
+    public float sizeZ = 50f;
+    public float height = 0f;
+
+    GraphicsBuffer matricesBuffer;
+    GraphicsBuffer argsBuffer;
+    int totalCount;
+
+    void Start()
+    {
+        totalCount = countX * countZ;
+
+        // 1) create structured buffer for matrices (float4x4 = 16 floats = 64 bytes)
+        matricesBuffer = new GraphicsBuffer(GraphicsBuffer.Target.Structured, totalCount, 16 * sizeof(float));
+        // 2) args buffer (5 uints): indexCountPerInstance, instanceCount, startIndexLocation, baseVertexLocation, startInstanceLocation
+        uint[] args = new uint[5] { (uint)grassMesh.GetIndexCount(0), (uint)totalCount, (uint)grassMesh.GetIndexStart(0), (uint)grassMesh.GetBaseVertex(0), 0u };
+        argsBuffer = new GraphicsBuffer(GraphicsBuffer.Target.IndirectArguments, 1, sizeof(uint) * args.Length);
+        argsBuffer.SetData(args);
+
+        // dispatch compute to fill matrices
+        int kernel = computeShader.FindKernel("CSMain");
+        computeShader.SetInt("_CountX", countX);
+        computeShader.SetInt("_CountZ", countZ);
+        computeShader.SetFloat("_SizeX", sizeX);
+        computeShader.SetFloat("_SizeZ", sizeZ);
+        computeShader.SetFloat("_Height", height);
+        computeShader.SetBuffer(kernel, "matrices", matricesBuffer);
+
+        int threadGroups = Mathf.CeilToInt(totalCount / 64.0f);
+        computeShader.Dispatch(kernel, threadGroups, 1, 1);
+
+        // bind buffer to material for per-instance matrix access (if shader reads it)
+        grassMaterial.SetBuffer("matrices", matricesBuffer);
+    }
+
+    void OnDisable()
+    {
+        matricesBuffer?.Dispose();
+        argsBuffer?.Dispose();
+    }
+
+    void Update()
+    {
+        // set render params: use simple bounds so Unity can cull
+        var bounds = new Bounds(transform.position, new Vector3(sizeX, 10f, sizeZ));
+        RenderParams rparams = new RenderParams(grassMaterial);
+        // the shader must use UNITY_INDIRECT_DRAW_ARGS / UnityIndirect.cginc if it needs instance id access
+
+        // call indirect draw
+        rparams.worldBounds = new Bounds(transform.position, new Vector3(sizeX, 10f, sizeZ));
+        Graphics.RenderMeshIndirect(rparams, grassMesh, argsBuffer);
+        // parameters: rparams, mesh, argsBuffer, commandCount=1, startCommand=0, worldBounds
+    }
+}