最近小弟做一个项目，其中涉及到一些温度云图(温场)的问题，论坛里找到有一两个发帖问的，但没有具体实现的办法。小弟接触unity3d时间也不长，作了一点点学习，写了一个简单的shader来实现温度云图。基本原理是给定平面上的几个点的位置和该点的温度信息，然后通过距离比的关系来算出平面上任意点的温度数值，再通过颜色反映出来。
Shader "Custom/TemperatureField" {
Properties {
_MainTex ("Base (RGB)", 2D) = "white" {}
_Point1("Temperature1",Range(0,100)) = 50
_Point2("Temperature2",Range(0,100)) = 50
_Point3("Temperature3",Range(0,100)) = 50
_Point4("Temperature4",Range(0,100)) = 50
}
SubShader {
AlphaTest Greater 0.1
pass
{
CGPROGRAM
// Upgrade NOTE: excluded shader from DX11, Xbox360, OpenGL ES 2.0 because it uses unsized arrays
#pragma exclude_renderers d3d11 xbox360 gles
#pragma target 3.0
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
sampler2D _MainTex;
float4 _MainTex_ST;
float _Point1;
float _Point2;
float _Point3;
float _Point4;
bool computer = false;
struct v2f {
float4 pos:SV_POSITION;
float2 uv:TEXCOORD0;
};
v2f vert(appdata_base v)
{
v2f o;
o.pos=mul(UNITY_MATRIX_MVP,v.vertex);
o.uv = TRANSFORM_TEX(v.texcoord,_MainTex);
return o;
}
float computerTemperature(float2 uv)
{
int plength = 3;
float _midPointX[3] = {0.2,0.8,0.5};
float _midPointY[3] = {0.7,0.9,0.4};
float _midPointT[3] = {10,20,90};
float d1 = sqrt(uv.x*uv.x+uv.y*uv.y);
float d2 = sqrt((1-uv.x)*(1-uv.x)+(1-uv.y)*(1-uv.y));
float d3 = sqrt(uv.x*uv.x+(1-uv.y)*(1-uv.y));
float d4 = sqrt((1-uv.x)*(1-uv.x)+uv.y*uv.y);
float m = 1/d1+1/d2+1/d3+1/d4;
float n = 1/d1*_Point1+1/d2*_Point4+1/d3*_Point3+1/d4*_Point2;
for (int i = 0 ; i < plength ; i++)
{
float dp = sqrt((uv.x-_midPointX)*(uv.x-_midPointX)+(uv.y-_midPointY)*(uv.y-_midPointY));
m = m + 1/dp;
n = n + 1/dp*_midPointT;
}
return n/m;
}
float4 frag(v2f i):COLOR
{
float4 outp;
float4 texCol = tex2D(_MainTex,i.uv);
float temp = computerTemperature(i.uv);
//float temp = computeArray(i.uv);
//图像区域，判定设置为颜色的A > 0.5,输出为材质颜色+光亮值
if(texCol.w>0.5)
{
if(temp >= 60)
outp = float4(1,0,0,1)*(temp-60)/40+float4(1,1,0,1)*(1-(temp-60)/40);
else if(temp >= 30)
outp = float4(1,1,0,1)*(temp-30)/30+float4(0,1,0,1)*(1-(temp-30)/30);
else
outp = float4(0,1,0,1)*(temp)/30+float4(0,0,1,1)*(1-(temp)/30);
}
else
outp = float4(0,0,0,0);
return outp;
}
ENDCG
}
}
FallBack "Diffuse"
}
其中_Point1到4是平面4个顶点上的温度值
_midPointX,_midPointY,_midPointT给出了平面内三个点的位置和温度值，实际应用中可以相应修改和增删
