Unity Shader学习：GPU Instance

稍微了解下关于gpu instance渲染优化的知识，以下是同屏6400个不同贴图的方块，用柏林噪声改变高度，加了阴影和漫反射。

csharp部分：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PerlinNoiseTest : MonoBehaviour {
    private float _seedX,_seedZ;
    public GameObject cubePrefab;
    private MaterialPropertyBlock props;
    private MeshRenderer meshRenderer;

    void Start () {

        _seedX = Random.value * 80f;
        _seedZ = Random.value * 80f;
        props = new MaterialPropertyBlock();
        //生成80*80的方块
        for (int i = 0; i < 80; i++)
        {
            for (int j= 0; j < 80; j++)
            {
                GameObject cube = Instantiate(cubePrefab);
                cube.transform.localPosition = new Vector3(i, 0, j);
                cube.transform.SetParent(transform);
                //根据perlin噪声赋值高度
                SetY(cube);
            }
        }
	}

    void SetY(GameObject cube)
    {
        float height=0;
        //采样的参数
        float xSample = (cube.transform.localPosition.x + _seedX)/15.0f;
        float zSample = (cube.transform.localPosition.z + _seedZ)/15.0f;
        //生成perlin噪声图
        float noise = Mathf.PerlinNoise(xSample, zSample);
        //根据不同的值设定高度以及贴图
        meshRenderer = cube.GetComponent<MeshRenderer>();
        if (noise<=0.1)
        {
            height = 0;
            props.SetFloat("_Index1", 1);
            props.SetFloat("_Index2", 0);
            props.SetFloat("_Index3", 0);
            props.SetFloat("_Index4", 0);
            meshRenderer.SetPropertyBlock(props);
        }
        else if (noise > 0.1 && noise <= 0.2)
        {
            height = 1;
            props.SetFloat("_Index1", 0);
            props.SetFloat("_Index2", 1);
            props.SetFloat("_Index3", 0);
            props.SetFloat("_Index4", 0);
            meshRenderer.SetPropertyBlock(props);
        }
        else if (noise > 0.2 && noise <= 0.3)
        {
            height = 2;
            props.SetFloat("_Index1", 0);
            props.SetFloat("_Index2", 0);
            props.SetFloat("_Index3", 1);
            props.SetFloat("_Index4", 0);
            meshRenderer.SetPropertyBlock(props);
        }
        else if (noise > 0.3 && noise <= 0.4)
        {
            height = 3;
            props.SetFloat("_Index1", 0);
            props.SetFloat("_Index2", 0);
            props.SetFloat("_Index3", 0);
            props.SetFloat("_Index4", 1);
            meshRenderer.SetPropertyBlock(props);
        }
        else if (noise > 0.4 && noise <= 0.5)
        {
            height = 4;
            props.SetFloat("_Index1", 0);
            props.SetFloat("_Index2", 0);
            props.SetFloat("_Index3", 0);
            props.SetFloat("_Index4", 1);
            meshRenderer.SetPropertyBlock(props);
        }
        else if (noise > 0.5 && noise <= 0.6)
        {
            height = 5;
            props.SetFloat("_Index1", 0);
            props.SetFloat("_Index2", 0);
            props.SetFloat("_Index3", 0);
            props.SetFloat("_Index4", 1);
            meshRenderer.SetPropertyBlock(props);
        }
        else if (noise > 0.6 && noise <= 0.7)
        {
            height = 6;
            props.SetFloat("_Index1", 0);
            props.SetFloat("_Index2", 0);
            props.SetFloat("_Index3", 0);
            props.SetFloat("_Index4", 1);
            meshRenderer.SetPropertyBlock(props);
        }
        else if (noise > 0.7 && noise <= 0.8)
        {
            height = 7;
            props.SetFloat("_Index1", 0);
            props.SetFloat("_Index2", 0);
            props.SetFloat("_Index3", 0);
            props.SetFloat("_Index4", 1);
            meshRenderer.SetPropertyBlock(props);
        }
        else if (noise > 0.8 && noise <= 0.9)
        {
            height = 8;
            props.SetFloat("_Index1", 0);
            props.SetFloat("_Index2", 0);
            props.SetFloat("_Index3", 0);
            props.SetFloat("_Index4", 1);
            meshRenderer.SetPropertyBlock(props);
        }
        else if (noise > 0.9)
        {
            height = 9;
            props.SetFloat("_Index1", 0);
            props.SetFloat("_Index2", 0);
            props.SetFloat("_Index3", 0);
            props.SetFloat("_Index4", 1);
            meshRenderer.SetPropertyBlock(props);
        }
        cube.transform.localPosition = new Vector3(cube.transform.localPosition.x, height, cube.transform.localPosition.z);
    }
}

shader部分：

Shader "Unlit/GPUInstanceDiffuse"
{
	Properties
	{
		//四种贴图
		_Tex1("Stone",2D) = "white"{}
		_Tex2("Water",2D) = "white"{}
		_Tex3("Soil",2D) = "white"{}
		_Tex4("Grass",2D) = "white"{}
		//贴图索引
		_Index1("Index1",float) = 1
		_Index2("Index2",float) = 1
		_Index3("Index3",float) = 1
		_Index4("Index4",float) = 1
	}
		SubShader
		{
			Tags { "RenderType" = "Opaque" "LightMode" = "ForwardBase"}
			LOD 100

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			//gpu instance
			#pragma multi_compile_instancing
			//阴影
			#pragma multi_compile_fwdbase

			#include "UnityCG.cginc"
			#include "Lighting.cginc"
			#include "AutoLight.cginc"

			sampler2D _Tex1;
			sampler2D _Tex2;
			sampler2D _Tex3;
			sampler2D _Tex4;

			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
				float3 normal:NORMAL;
				UNITY_VERTEX_INPUT_INSTANCE_ID				
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				UNITY_VERTEX_INPUT_INSTANCE_ID
				float4 pos : SV_POSITION;
				float3 worldNormal:TEXCOORD1;
				float3 worldPos:TEXCOORD2;
				SHADOW_COORDS(3)
			};
			
			//不同的属性
			UNITY_INSTANCING_BUFFER_START(Props)
			UNITY_DEFINE_INSTANCED_PROP(float, _Index1)
			UNITY_DEFINE_INSTANCED_PROP(float, _Index2)
			UNITY_DEFINE_INSTANCED_PROP(float, _Index3)
			UNITY_DEFINE_INSTANCED_PROP(float, _Index4)
			UNITY_INSTANCING_BUFFER_END(Props)

			v2f vert (appdata v)
			{
				v2f o;
				UNITY_SETUP_INSTANCE_ID(v);
				UNITY_TRANSFER_INSTANCE_ID(v, o);
				o.pos = UnityObjectToClipPos(v.vertex);
				o.worldNormal = normalize(mul(v.normal, (float3x3)unity_WorldToObject));
				o.uv = v.uv;
				o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
				TRANSFER_SHADOW(o);
				return o;
			}
			
			float4 frag (v2f i) : SV_Target
			{
				float3 worldNormal = i.worldNormal;
				float3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz;
				float3 lightDir = normalize(_WorldSpaceLightPos0.xyz);
				float3 diffuse = _LightColor0.rgb*saturate(0.5*dot(worldNormal, lightDir) + 0.5);
				float shadow = SHADOW_ATTENUATION(i);
				UNITY_LIGHT_ATTENUATION(atten, i, i.worldPos.xyz);
				float3 mainTex1,mainTex2,mainTex3,mainTex4 =float3(0,0,0);
				UNITY_SETUP_INSTANCE_ID(i);

				mainTex1 = tex2D(_Tex1, i.uv).xyz;
				mainTex2 = tex2D(_Tex2, i.uv).xyz;
				mainTex3 = tex2D(_Tex3, i.uv).xyz;
				mainTex4 = tex2D(_Tex4, i.uv).xyz;

				//根据传来的0和1选择贴图
				return float4(((mainTex1 * UNITY_ACCESS_INSTANCED_PROP(Props, _Index1)+
								mainTex2 * UNITY_ACCESS_INSTANCED_PROP(Props, _Index2)+
								mainTex3 * UNITY_ACCESS_INSTANCED_PROP(Props, _Index3)+
								mainTex4 * UNITY_ACCESS_INSTANCED_PROP(Props, _Index4) 
								)*diffuse+ambient)*shadow,1);
			}
			ENDCG
		}
	}
	fallback "Diffuse"
}