Shader with custum lightmap that use uv2.

Unity Engine
1

Hi guys.
Could anyone explain me how to write a shader that works in the following way: It should use Diffusemap with uv1 and a lightmap with uv2. Or maybe im not the first who needs that shader and its already exists.

2

Here’s one I’m using in my project.

Shader "Custom/Custom Lightmapped" {
	Properties {
		_MainTex ("Diffuse (RGB)", 2D) = "grey" {}
		_LightMap ("Lightmap (RGB)", 2D) = "grey" {}
	}

	Category {
		Tags { "RenderType"="Opaque" "IgnoreProjector"="True" "Queue"="Geometry" }
		Lighting Off

		SubShader {
			LOD 200

			Pass {
				Tags { "LightMode" = "Always" }
				CGPROGRAM
					#pragma vertex vert
					#pragma fragment frag
					#pragma fragmentoption ARB_precision_hint_fastest

					#include "UnityCG.cginc"

					struct appdata {
						float4 vertex : POSITION;
						float2 texcoord : TEXCOORD0;
						float2 texcoord1 : TEXCOORD1;
					};

					struct v2f {
						float4	pos : SV_POSITION;
						float4	uv : TEXCOORD0;
					};

					v2f vert (appdata v) {
						v2f o;

						o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
						o.uv.xy = v.texcoord.xy;
						o.uv.zw = v.texcoord1.xy;

						return o;
					}

					sampler2D _MainTex, _Lightmap;

					fixed4 frag(v2f i) : COLOR {
						fixed4 c;
						c.rgb = tex2D ( _MainTex, i.uv.xy ).rgb; // Diffuse.
						c.rgb *= tex2D ( _Lightmap, i.uv.zw ).rgb * 2; // Lightmap.
						c.a = 1;
						return c;
					}
				ENDCG
			}
		}

		SubShader {
			LOD 100

			Pass {
				Tags { "LightMode" = "Always" }

				Lighting Off
				BindChannels {
					Bind "Vertex", vertex
					Bind "texcoord", texcoord0
					Bind "texcoord1", texcoord1
				}

				SetTexture [_MainTex] {
					combine texture
				}

				SetTexture [_Lightmap] {
					combine texture * previous DOUBLE
				}
			}
		}
		
	}
	FallBack Off
}
3

Thank you. :slight_smile:

4

Bear in mind I’m currently doubling the lightmap. So anything that’s 50% grey will turn out fullbright, but anything lighter than that will start to overexpose the base texture - up to 2x it’s brightness if you put white in the lightmap.

To disable that and simply have the lightmap multiply over the diffuse, find the line

c.rgb *= tex2D ( _Lightmap, i.uv.zw ).rgb * 2; // Lightmap.

and remove the “* 2” to get

c.rgb *= tex2D ( _Lightmap, i.uv.zw ).rgb; // Lightmap.

and also find the line

combine texture * previous DOUBLE

and remove the “DOUBLE” to get

combine texture * previous