【游戏-unity】Shader全景图实现。为了让unity项目中的建筑场景显的逼真，通常的做法是使用一个360°无死角的全景背景来避免穿帮，这篇文章给大家介绍使用shader实现全景图。

Latitude.shader

//思路
//1. 通过法线方向求平面坐标。x=atan(x/z),y=acos(y/r) r为半径;
//2. 通过ddx,ddy 偏导数模糊极坐标像素解决极坐标问题。
//3. 通过反射比较真实的扑捉视觉。

Shader"QQ/Sky/Latitude"  
{  
	Properties  
	{  
		_MainTex("Texture",2D)="white"{}  
		[Enum(UnityEngine.Rendering.CullMode)]_Cull("CullMode",float)=2  
		[Enum(Off,0,On,1)]_Inverse("inverse",float)=0  
	}  
		SubShader  
		{  
			Tags{"RenderType"="Opaque"}  
			LOD100  
			Pass  
			{  
				Cull[_Cull]  
				CGPROGRAM  
				#pragmavertexvert  
				#pragmafragmentfrag  
				#include"UnityCG.cginc"  
				structa2v  
				{  
					float4vertex:POSITION;  
					float3normal:NORMAL;  
				};  
				structv2f  
				{  
					float4pos:SV_POSITION;  
					float3normal:TEXCOORD0;  
					float3wPos:TEXCOORD1;  
				};  
				sampler2D_MainTex;  
				float4_MainTex_ST;  
				float_Cull;  
				float_Inverse;  
				v2fvert(a2vv)  
				{  
					v2fo;  
					o.pos=mul(UNITY_MATRIX_MVP,v.vertex);  
					o.normal=v.normal;  
					o.wPos=mul(unity_ObjectToWorld,v.vertex);  
					returno;  
				}  
				fixed4frag(v2fi):SV_Target  
				{  
					float3nor=normalize(i.normal);  
					float3viewDir=normalize(_WorldSpaceCameraPos.xyz-i.wPos);  
					float3refl=(_Inverse>0?1:-1)*reflect(viewDir,nor);  
					floatu=atan2(refl.x,refl.z)/UNITY_PI;  
					u=(u+1.0)*0.5;  
					floatv=acos(refl.y)/UNITY_PI;  
					float2uv=float2(u,v)*_MainTex_ST.xy+_MainTex_ST.zw;  
					fixed4col=tex2D(_MainTex,uv,float2(0,0),float2(0,0));  
					returncol;  
				}  
				ENDCG  
			}  
		}  
}

https://gameinstitute.qq.com/community/detail/128718

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