【Unity】Shader学习笔记-粒子效果自定义数据

发表于 2024-09-10 更新于 2024-09-14

Shader制作

这里需要注意的是：

粒子系统的参数并不是直接将float类型的数据来当做参数，而是将不同通道的UV当做参数
当做通道的参数需要将UV Set设置为非0

源码(删除掉了注释和预编译)：

Shader "CustomizeInformation_ASE"
{
	Properties
	{
		_MainTexture("MainTexture", 2D) = "white" {}
		_NoiseTexture("NoiseTexture", 2D) = "white" {}
		_DissolveTexture("DissolveTexture", 2D) = "white" {}
		[HideInInspector] _texcoord( "", 2D ) = "white" {}

	}
	
	SubShader
	{
		Tags { "RenderType"="Transparent" "Queue"="Transparent" }
	LOD 100

		CGINCLUDE
		#pragma target 3.0
		ENDCG
		Blend SrcAlpha OneMinusSrcAlpha
		AlphaToMask Off
		Cull Back
		ColorMask RGBA
		ZWrite Off
		ZTest LEqual
		Offset 0 , 0
		
		Pass
		{
			Name "Unlit"

			CGPROGRAM

			#pragma vertex vert
			#pragma fragment frag
			#pragma multi_compile_instancing
			#include "UnityCG.cginc"
			
			struct appdata
			{
				float4 vertex : POSITION;
				float4 color : COLOR;
				float4 ase_texcoord : TEXCOORD0;
				float4 ase_texcoord1 : TEXCOORD1;
				UNITY_VERTEX_INPUT_INSTANCE_ID
			};
			
			struct v2f
			{
				float4 vertex : SV_POSITION;
				float4 ase_texcoord1 : TEXCOORD1;
				float4 ase_texcoord2 : TEXCOORD2;
				UNITY_VERTEX_INPUT_INSTANCE_ID
				UNITY_VERTEX_OUTPUT_STEREO
			};

			uniform sampler2D _MainTexture;
			uniform float4 _MainTexture_ST;
			uniform sampler2D _NoiseTexture;
			uniform float4 _NoiseTexture_ST;
			uniform sampler2D _DissolveTexture;
			uniform float4 _DissolveTexture_ST;

			v2f vert ( appdata v )
			{
				v2f o;
				UNITY_SETUP_INSTANCE_ID(v);
				UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
				UNITY_TRANSFER_INSTANCE_ID(v, o);

				o.ase_texcoord1.xy = v.ase_texcoord.xy;
				o.ase_texcoord2 = v.ase_texcoord1;
				
				//setting value to unused interpolator channels and avoid initialization warnings
				o.ase_texcoord1.zw = 0;
				float3 vertexValue = float3(0, 0, 0);
				vertexValue = vertexValue;
				v.vertex.xyz += vertexValue;
				o.vertex = UnityObjectToClipPos(v.vertex);

				return o;
			}
			
			fixed4 frag (v2f i ) : SV_Target
			{
				UNITY_SETUP_INSTANCE_ID(i);
				UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(i);
				fixed4 finalColor;
				float2 uv_MainTexture = i.ase_texcoord1.xy * _MainTexture_ST.xy + _MainTexture_ST.zw;
				float4 texCoord5 = i.ase_texcoord2;
				texCoord5.xy = i.ase_texcoord2.xy * float2( 1,1 ) + float2( 0,0 );
				float2 appendResult6 = (float2(texCoord5.x , texCoord5.y));
				float2 uv_NoiseTexture = i.ase_texcoord1.xy * _NoiseTexture_ST.xy + _NoiseTexture_ST.zw;
				float2 temp_cast_0 = (tex2D( _NoiseTexture, uv_NoiseTexture ).r).xx;
				float2 lerpResult7 = lerp( ( uv_MainTexture + appendResult6 ) , temp_cast_0 , texCoord5.z);
				float4 tex2DNode1 = tex2D( _MainTexture, lerpResult7 );
				float2 uv_DissolveTexture = i.ase_texcoord1.xy * _DissolveTexture_ST.xy + _DissolveTexture_ST.zw;
				float4 appendResult11 = (float4(tex2DNode1.rgb , ( tex2DNode1.a * step( texCoord5.w , tex2D( _DissolveTexture, uv_DissolveTexture ).r ) )));
				
				finalColor = appendResult11;
				return finalColor;
			}
			ENDCG
		}
	}
	Fallback Off
}

代码解析（使用反推法）：

可以通过lerp函数看出来，texCoord5就是我们的UVSet=1

fixed4 frag (v2f i ) : SV_Target
{
    ...
	float2 lerpResult7 = lerp( ( uv_MainTexture + appendResult6 ) , temp_cast_0 , texCoord5.z);
    ...
}

所以结构体v2f中的ase_texcoord2存储的就是UVSet=1

fixed4 frag (v2f i ) : SV_Target
{
    ...
	float4 texCoord5 = i.ase_texcoord2;
    ...
	float2 lerpResult7 = lerp( ( uv_MainTexture + appendResult6 ) , temp_cast_0 , texCoord5.z);
    ...
}

结构体v2f中的ase_texcoord2是从appdata的ase_texcoord1赋值过来的

v2f vert ( appdata v )
{
    ...
    o.ase_texcoord2 = v.ase_texcoord1;
    ...
}

还需要注意到结构体appdata中的ase_texcoord.zw并没有被赋值（整个代码ase_texcoord只使用过一次）
1
2
3
4
5
6
v2f vert ( appdata v )
{
...
o.ase_texcoord1.xy = v.ase_texcoord.xy;
...
}

粒子系统设置

勾选Custom Vertex Streams并按顺序添加UV2和Custom1.xyzw
- UV2(TEXCOORD0.zw)：初始化appdata中的ase_texcoord.zw，对应代码解析的第四步
- Custom1.xyzw(TEXCOORD1.xyzw)：将下一步的Custom1.xyzw对应上appdata中的ase_texcoord1，对应代码解析的第三步
1
2
3
4
5
6
7
8
struct appdata
{
float4 vertex : POSITION;
float4 color : COLOR;
float4 ase_texcoord : TEXCOORD0;
float4 ase_texcoord1 : TEXCOORD1;
UNITY_VERTEX_INPUT_INSTANCE_ID
};