Graphics.DrawMeshInstancedIndirect

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public static void DrawMeshInstancedIndirect (Mesh mesh, int submeshIndex, Material material, Bounds bounds, ComputeBuffer bufferWithArgs, int argsOffset= 0, MaterialPropertyBlock properties= null, Rendering.ShadowCastingMode castShadows= ShadowCastingMode.On, bool receiveShadows= true, int layer= 0, Camera camera= null, Rendering.LightProbeUsage lightProbeUsage= LightProbeUsage.BlendProbes, LightProbeProxyVolume lightProbeProxyVolume= null);

Parameters

mesh要绘制的 Mesh
submeshIndex要绘制网格的哪个子集。这只适用于由若干种材质构成的网格。
material要使用的 Material
bounds围绕要绘制的实例的包围体。
bufferWithArgsGPU 缓冲区包含相应的参数,指示要绘制此网格的实例数。
argsOffset缓冲区中的字节偏移,绘制参数起始位置。
properties要应用的其他材质属性。请参阅 MaterialPropertyBlock
castShadows网格是否应投射阴影?
receiveShadows网格是否应接受阴影?
layer要使用的 Layer
camera如果为 /null/(默认值),将在所有摄像机中绘制网格。否则,仅在给定摄像机中绘制网格。
lightProbeUsage实例的 LightProbeUsage

Description

使用 GPU 实例化多次绘制同一网格。

类似于 Graphics.DrawMeshInstanced,此函数用于绘制同一网格的多个实例,但与之不同的是,此函数中代表要绘制实例数的参数来自 /bufferWithArgs/。

如果您需要使用实例化的着色器多次绘制同一网格,则可以使用该函数。这些网格不会被视锥体或烘焙遮挡物做进一步的剔除处理,也不进行排序以提高透明度或 Z 效率。

带参数的缓冲区 bufferWithArgs 必须在给定的 argsOffset 偏移处具有五个整数: 每个实例的索引数、实例数、起始索引位置、基顶点位置、起始实例位置。

下面是一个可用于绘制同一网格的多个实例的脚本:

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour { public int instanceCount = 100000; public Mesh instanceMesh; public Material instanceMaterial; public int subMeshIndex = 0;

private int cachedInstanceCount = -1; private int cachedSubMeshIndex = -1; private ComputeBuffer positionBuffer; private ComputeBuffer argsBuffer; private uint[] args = new uint[5] { 0, 0, 0, 0, 0 };

void Start() { argsBuffer = new ComputeBuffer(1, args.Length * sizeof(uint), ComputeBufferType.IndirectArguments); UpdateBuffers(); }

void Update() { // Update starting position buffer if (cachedInstanceCount != instanceCount || cachedSubMeshIndex != subMeshIndex) UpdateBuffers();

// Pad input if (Input.GetAxisRaw("Horizontal") != 0.0f) instanceCount = (int)Mathf.Clamp(instanceCount + Input.GetAxis("Horizontal") * 40000, 1.0f, 5000000.0f);

// Render Graphics.DrawMeshInstancedIndirect(instanceMesh, subMeshIndex, instanceMaterial, new Bounds(Vector3.zero, new Vector3(100.0f, 100.0f, 100.0f)), argsBuffer); }

void OnGUI() { GUI.Label(new Rect(265, 25, 200, 30), "Instance Count: " + instanceCount.ToString()); instanceCount = (int)GUI.HorizontalSlider(new Rect(25, 20, 200, 30), (float)instanceCount, 1.0f, 5000000.0f); }

void UpdateBuffers() { // Ensure submesh index is in range if (instanceMesh != null) subMeshIndex = Mathf.Clamp(subMeshIndex, 0, instanceMesh.subMeshCount - 1);

// Positions if (positionBuffer != null) positionBuffer.Release(); positionBuffer = new ComputeBuffer(instanceCount, 16); Vector4[] positions = new Vector4[instanceCount]; for (int i = 0; i < instanceCount; i++) { float angle = Random.Range(0.0f, Mathf.PI * 2.0f); float distance = Random.Range(20.0f, 100.0f); float height = Random.Range(-2.0f, 2.0f); float size = Random.Range(0.05f, 0.25f); positions[i] = new Vector4(Mathf.Sin(angle) * distance, height, Mathf.Cos(angle) * distance, size); } positionBuffer.SetData(positions); instanceMaterial.SetBuffer("positionBuffer", positionBuffer);

// Indirect args if (instanceMesh != null) { args[0] = (uint)instanceMesh.GetIndexCount(subMeshIndex); args[1] = (uint)instanceCount; args[2] = (uint)instanceMesh.GetIndexStart(subMeshIndex); args[3] = (uint)instanceMesh.GetBaseVertex(subMeshIndex); } else { args[0] = args[1] = args[2] = args[3] = 0; } argsBuffer.SetData(args);

cachedInstanceCount = instanceCount; cachedSubMeshIndex = subMeshIndex; }

void OnDisable() { if (positionBuffer != null) positionBuffer.Release(); positionBuffer = null;

if (argsBuffer != null) argsBuffer.Release(); argsBuffer = null; } }

下面是一个表面着色器,可以与上面的示例脚本配合使用:

          Shader "Instanced/InstancedSurfaceShader" {
    Properties {
        _MainTex ("Albedo (RGB)", 2D) = "white" {}
        _Glossiness ("Smoothness", Range(0,1)) = 0.5
        _Metallic ("Metallic", Range(0,1)) = 0.0
    }
    SubShader {
        Tags { "RenderType"="Opaque" }
        LOD 200

CGPROGRAM // Physically based Standard lighting model #pragma surface surf Standard addshadow fullforwardshadows #pragma multi_compile_instancing #pragma instancing_options procedural:setup

sampler2D _MainTex;

struct Input { float2 uv_MainTex; };

#ifdef UNITY_PROCEDURAL_INSTANCING_ENABLED StructuredBuffer<float4> positionBuffer; #endif

void rotate2D(inout float2 v, float r) { float s, c; sincos(r, s, c); v = float2(v.x * c - v.y * s, v.x * s + v.y * c); }

void setup() { #ifdef UNITY_PROCEDURAL_INSTANCING_ENABLED float4 data = positionBuffer[unity_InstanceID];

float rotation = data.w * data.w * _Time.y * 0.5f; rotate2D(data.xz, rotation);

unity_ObjectToWorld._11_21_31_41 = float4(data.w, 0, 0, 0); unity_ObjectToWorld._12_22_32_42 = float4(0, data.w, 0, 0); unity_ObjectToWorld._13_23_33_43 = float4(0, 0, data.w, 0); unity_ObjectToWorld._14_24_34_44 = float4(data.xyz, 1); unity_WorldToObject = unity_ObjectToWorld; unity_WorldToObject._14_24_34 *= -1; unity_WorldToObject._11_22_33 = 1.0f / unity_WorldToObject._11_22_33; #endif }

half _Glossiness; half _Metallic;

void surf (Input IN, inout SurfaceOutputStandard o) { fixed4 c = tex2D (_MainTex, IN.uv_MainTex); o.Albedo = c.rgb; o.Metallic = _Metallic; o.Smoothness = _Glossiness; o.Alpha = c.a; } ENDCG } FallBack "Diffuse" }

下面是一个自定义着色器,可以与上面的示例脚本配合使用:

          Shader "Instanced/InstancedShader" {
    Properties {
        _MainTex ("Albedo (RGB)", 2D) = "white" {}
    }
    SubShader {

Pass {

Tags {"LightMode"="ForwardBase"}

CGPROGRAM

#pragma vertex vert #pragma fragment frag #pragma multi_compile_fwdbase nolightmap nodirlightmap nodynlightmap novertexlight #pragma target 4.5

#include "UnityCG.cginc" #include "UnityLightingCommon.cginc" #include "AutoLight.cginc"

sampler2D _MainTex;

#if SHADER_TARGET >= 45 StructuredBuffer<float4> positionBuffer; #endif

struct v2f { float4 pos : SV_POSITION; float2 uv_MainTex : TEXCOORD0; float3 ambient : TEXCOORD1; float3 diffuse : TEXCOORD2; float3 color : TEXCOORD3; SHADOW_COORDS(4) };

void rotate2D(inout float2 v, float r) { float s, c; sincos(r, s, c); v = float2(v.x * c - v.y * s, v.x * s + v.y * c); }

v2f vert (appdata_full v, uint instanceID : SV_InstanceID) { #if SHADER_TARGET >= 45 float4 data = positionBuffer[instanceID]; #else float4 data = 0; #endif

float rotation = data.w * data.w * _Time.x * 0.5f; rotate2D(data.xz, rotation);

float3 localPosition = v.vertex.xyz * data.w; float3 worldPosition = data.xyz + localPosition; float3 worldNormal = v.normal;



float3 ndotl = saturate(dot(worldNormal, _WorldSpaceLightPos0.xyz)); float3 ambient = ShadeSH9(float4(worldNormal, 1.0f)); float3 diffuse = (ndotl * _LightColor0.rgb); float3 color = v.color;

v2f o; o.pos = mul(UNITY_MATRIX_VP, float4(worldPosition, 1.0f)); o.uv_MainTex = v.texcoord; o.ambient = ambient; o.diffuse = diffuse; o.color = color; TRANSFER_SHADOW(o) return o; }

fixed4 frag (v2f i) : SV_Target { fixed shadow = SHADOW_ATTENUATION(i); fixed4 albedo = tex2D(_MainTex, i.uv_MainTex); float3 lighting = i.diffuse * shadow + i.ambient; fixed4 output = fixed4(albedo.rgb * i.color * lighting, albedo.w); UNITY_APPLY_FOG(i.fogCoord, output); return output; }

ENDCG } } }