Vertex Shader中的几何变换

本文给大家介绍几个Vertex Shader中常用的几何变换

如果是刚开始接触几何变换内容学起来是比较吃力的！

这种思维需要不断的磨合、锻炼

对于Shader几何变换我总结成了4个字：并行、时差

并行：

渲染管线是一系列并行的渲然流水线。通俗来说，每个顶点的计算是同时的。

时差：

每个顶点会不断的计算（包括颜色、位置等等）。

总而言之：并行是指全部顶点同时计算，时差是指每个顶点不断的计算。

接下来介绍下几个常用的几何变换

一、顶点旋转几何变换

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

//顶点旋转
Shader "Custom/RotateShader" 
{
	Properties 
	{
		_RotateSpeed("RotateSpeed",range(0,500))=5
	}
	SubShader 
	{

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

			float _RotateSpeed;

			struct a2v
			{
				float4 position:POSITION;
			};

			a2v vert(appdata_base v)
			{
				a2v paratem;
				float l = length(v.vertex);
				
				float3x3 rotateM =
				{
					float3(sin(l+_Time.w*_RotateSpeed),0,-cos(l+_Time.w*_RotateSpeed)),
					float3(0,1,0),
					float3(cos(l+_Time.w*_RotateSpeed), 0, sin(l+_Time.w*_RotateSpeed)),
				};

				float3 position = mul(rotateM,v.vertex);
				paratem.position = UnityObjectToClipPos(position);

				return paratem;
			}

			fixed4 frag():COLOR
			{
				return fixed4(0.5,0.5,0.5,1);
			}
			ENDCG
		}
	}
	FallBack "Diffuse"
}

效果图：

二、地形几何变换

// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

//地形
Shader "Custom/MountainShader" 
{
	Properties 
	{
		_Redium("Redium",float)=5
		_OriginX("OriginX",float)=5
		_OriginY("OriginY",float)=5
	}
	SubShader 
	{

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

			float _Redium;
			float _OriginX;
			float _OriginY;

			void vert(appdata_base v,out float4 position:SV_POSITION)
			{
				//将顶点的世界坐标转化为世界坐标
				float4 wordVertex=mul(unity_ObjectToWorld,v.vertex);
				//计算坡度
				float height=_Redium-length(v.vertex.xz-float2(_OriginX,_OriginY));
				height=height>=0?height:0;

				float4 newPos=float4(v.vertex.x,height,v.vertex.z,v.vertex.w);
				position=UnityObjectToClipPos(newPos) ;
			}

			fixed4 frag(in float4 position:SV_POSITION):COLOR
			{				
				return fixed4(0,0.8,0,1);
			}
			ENDCG
		}
	}
	FallBack "Diffuse"
}

效果图：

三、扭曲几何变换

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

//扭曲
Shader "Custom/TwistShader" 
{
	Properties 
	{
	}
	SubShader 
	{
		pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#include "UnityCG.cginc"

			void vert(appdata_base v,out float4 position:SV_POSITION)
			{
				float weight=v.vertex.z+_Time.y;

				v.vertex.x=v.vertex.x*(cos(weight)/8+0.5);

				position=UnityObjectToClipPos(v.vertex);
			}

			fixed4 frag(in float4 position:SV_POSITION):COLOR
			{				
				return fixed4(0,0.8,0,1);
			}
			ENDCG
		}
	}
	FallBack "Diffuse"
}

效果图：

四、水波几何变换

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

//水波
Shader "Custom/Wave01Shader" 
{
	Properties 
	{
	}
	SubShader 
	{
		pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#include "UnityCG.cginc"

			void vert(appdata_base v,out float4 position:SV_POSITION)
			{
				//改变高度
				v.vertex.y=sin(_Time.y+v.vertex.x);
				position=UnityObjectToClipPos(v.vertex);			
			}

			fixed4 frag():COLOR
			{	
				return fixed4(0,0.8,0,1);
			}
			ENDCG
		}
	}
	FallBack "Diffuse"
}

效果图：略

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

//地形
Shader "Custom/Wave02Shader" 
{
	Properties 
	{
	}
	SubShader 
	{
		pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#include "UnityCG.cginc"

			void vert(appdata_base v,out float4 position:SV_POSITION)
			{
				//改变高度
				v.vertex.y+=0.2*sin( -length(v.vertex.xz)*2+_Time.y);
				position=UnityObjectToClipPos(v.vertex);			
			}

			fixed4 frag():COLOR
			{	
				return fixed4(0,0.8,0,1);
			}
			ENDCG
		}
	}
	FallBack "Diffuse"
}

效果图：

总结：

一、知道渲染管线流水线（并行、时差）

二、appdata_base中的v.vertex是顶点原始位置