Unity GPU Instance(大量相同网格物体合批)

时间 2019-11-06

标签 unity gpu instance 大量相同网格物体繁體版

原文原文链接

前言

在Unity中同网格同材质的模型是能够合批的
动态批处理和静态批处理均可以合批可是都有其限制
动态批处理有顶点数不能超过900的限制只适合比较简单的模型
静态批处理的物体不能移动、旋转、缩放而且须要消耗额外的内存来存储合并后的物体html

若是动态静态批处理都没法使用可否用其余方式合批呢？
能够尝试一下GPU Instance 虽然也有所限制可是提供了更多可能segmentfault

使用GPU Instancing的条件

1.Shader支持GPU Instancing
2.硬件支持GPI Instancing
3.代码动态绘制物体app

硬件需求：dom

GPU Instancing is available on the following platforms and APIs:
·DirectX 11 and DirectX 12 on Windows
·OpenGL Core 4.1+/ES3.0+ on Windows, macOS, Linux, iOS and Android
·Metal on macOS and iOS
·Vulkan on Windows and Android
·PlayStation 4 and Xbox One
·WebGL (requires WebGL 2.0 API)

限制状况:ide

下列状况不能使用Instancing：
·使用Lightmap的物体
·受不一样Light Probe / Reflection Probe影响的物体
·使用包含多个Pass的Shader的物体，只有第一个Pass能够Instancing前向渲染时，
受多个光源影响的物体只有Base Pass能够instancing，Add Passes不行

GPU Instance测试

GPU Instancing确实能够动态合批可是须要Shader + 硬件 + 代码的支持
好处是能够解决动态批处理解决不了的问题没900顶点的限制性能

ps:虽然官方的Standard Shader提供了GPU Instance的选项可是给材质设置不一样颜色后合批失败了这里有坑使用了其余Shader后解决学习

测试效果：

测试

测试代码：优化

using UnityEngine;
using System.Collections.Generic;

/// <summary>
/// PropertyBlockTest
/// ZhangYu 2019-06-17
/// <para>Blog:https://segmentfault.com/a/1190000019553301</para>
/// </summary>
public class PropertyBlockTest : MonoBehaviour {

    public GameObject prefab;
    public int count = 100;
    private Mesh insMesh;
    private Material insMaterial;
    private List<Matrix4x4> insMatrices;
    private MaterialPropertyBlock insBlock;
    private List<Color> insColors;
    private int colorID;

    private void Start () {
        GPUInstanceByBlock();
        //GPUInstanceByDrawMesh();
    }

    private void Update() {
        if (insMesh != null) DrawMeshes();
    }

    // 方法1：经过Shader + PropertyBlock 实现GPU Instance
    private void GPUInstanceByBlock() {
        MaterialPropertyBlock block = new MaterialPropertyBlock();
        int colorID = Shader.PropertyToID("_Color");
        GameObject[] objs = new GameObject[count];
        for (int i = 0; i < count; i++) {
            Vector3 position = new Vector3(Random.Range(-8, 8f), Random.Range(-4, 4f), 3);
            Color color = new Color(Random.Range(0, 1f), Random.Range(0, 1f), Random.Range(0, 1f));
            block.SetColor(colorID, color);
            GameObject obj = Instantiate(prefab);
            // 用Block代替Material设置值 这样就能合批了
            obj.GetComponent<MeshRenderer>().SetPropertyBlock(block);
            obj.transform.position = position;
            obj.SetActive(true);
        }
    }

    // 方法2：经过DrawMesh + Shader + PropertyBlock实现GPU Instance
    private void GPUInstanceByDrawMesh() {
        insMesh = prefab.GetComponent<MeshFilter>().mesh;
        insMaterial = prefab.GetComponent<Renderer>().material;
        insMatrices = new List<Matrix4x4>();
        insColors = new List<Color>();
        insBlock = new MaterialPropertyBlock();
        colorID = Shader.PropertyToID("_Color");
        for (int i = 0; i < count; i++) {
            Vector3 position = new Vector3(Random.Range(-8, 8f), Random.Range(-4, 4f), 3);
            Quaternion rotation = prefab.transform.rotation;
            Color color = new Color(Random.Range(0, 1f), Random.Range(0, 1f), Random.Range(0, 1f));
            // Position + Rotation + Scale > Matrix4x4
            Matrix4x4 matrix = TransformToMatrix(position, rotation);
            insMatrices.Add(matrix);
            insColors.Add(color);
        }
    }

    private void DrawMeshes() {
        // 测试结果：
        // 同网格 同材质 能够合批 须要Shader支持GPU Instance + 用PropertyBlock设置参数

        // DrawMeshInstanced() 一次绘制多个物体 调用一次 一个DrawCall
        //Graphics.DrawMeshInstanced(insMesh, 0, insMaterial, insMatrices, insBlock);

        // DrawMesh() 一次绘制一个物体 屡次调用 能够合成一批
        for (int i = 0; i < count; i++) {
            insBlock.SetColor(colorID, insColors[i]);
            Graphics.DrawMesh(insMesh, insMatrices[i], insMaterial, 1, Camera.main, 0, insBlock);
        }
    }

    private Matrix4x4 TransformToMatrix(Vector3 position) {
        return Matrix4x4.TRS(position, Quaternion.identity, Vector3.one);
    }

    private Matrix4x4 TransformToMatrix(Vector3 position, Quaternion rotation) {
        return Matrix4x4.TRS(position, rotation, Vector3.one);
    }

    private Matrix4x4 TransformToMatrix(Vector3 position, Quaternion rotation, Vector3 scale) {
        return Matrix4x4.TRS(position, rotation, scale);
    }

}

测试Shader：ui

Shader "SimplestInstancedShader"
{
    Properties
    {
        _Color("Color", Color) = (1, 1, 1, 1)
    }

        SubShader
    {
        Tags{ "RenderType" = "Opaque" }
        LOD 100

        Pass
    {
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma multi_compile_instancing
#include "UnityCG.cginc"

    struct appdata
    {
        float4 vertex : POSITION;
        UNITY_VERTEX_INPUT_INSTANCE_ID
    };

    struct v2f
    {
        float4 vertex : SV_POSITION;
        UNITY_VERTEX_INPUT_INSTANCE_ID // necessary only if you want to access instanced properties in fragment Shader.
    };

        UNITY_INSTANCING_BUFFER_START(Props)
        UNITY_DEFINE_INSTANCED_PROP(float4, _Color)
        UNITY_INSTANCING_BUFFER_END(Props)

        v2f vert(appdata v)
    {
        v2f o;

        UNITY_SETUP_INSTANCE_ID(v);
        UNITY_TRANSFER_INSTANCE_ID(v, o); // necessary only if you want to access instanced properties in the fragment Shader.

        o.vertex = UnityObjectToClipPos(v.vertex);
        return o;
    }

    fixed4 frag(v2f i) : SV_Target
    {
        UNITY_SETUP_INSTANCE_ID(i); // necessary only if any instanced properties are going to be accessed in the fragment Shader.
        return  UNITY_ACCESS_INSTANCED_PROP(Props, _Color);
    }
        ENDCG
    }
    }
}

MaterialPropertyBlock的说明：
材质属性块被用于Graphics.DrawMesh和Renderer.SetPropertyBlock两个API，当咱们想要绘制许多相同材质但不一样属性的对象时可使用它。例如你想改变每一个绘制网格的颜色，可是它却不会改变渲染器的状态。
简单来讲利用PropertyBlock设置属性不会产生新的Mesh和Material 速度快性能高

SkinMeshRender的GPU Instancing

Unity官方开源的Animation Instacing: https://blogs.unity3d.com/cn/...

CSDN博主
《Unity中使用GPU Instancing优化SkinnedMesh渲染》https://blog.csdn.net/xoyojan...

参考资料：
《[unity]GPU Instance学习》：https://www.jianshu.com/p/ecf...
《使用MaterialPropertyBlock来替换Material属性操做》 https://blog.uwa4d.com/archiv...
《Unity3D研究院GPU Instancing实战（九十七）》https://www.xuanyusong.com/ar...

转载请标明原文地址：https://segmentfault.com/a/11...