Cg Shader Patterns

Multiple Pixel Lights

Cg shaders that wish to render multiple pixel lights take the following pattern:

• A base texture pass with the PixelOrNone tag. This pass just renders the texture without lighting and with the ambient light taken into account.
• A pixel light pass that renders the texture and the lighting. Its easiest to do this

Unity first renders the PixelOrNone pass and then blend the Pixel passes on top of this per pixel light. You do not need to set blending modes on the pixel lighting pass, Unity automagically blends the lighting pass onto the ambient base pass.

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Shader "Pixel Light Template"  {

Properties {
    _Color ("Main Color", Color) = (1,1,1,1)
    _Shininess ("Shininess", Range (0.03, 1)) = 0.078125
    _MainTex ("Base (RGB) Gloss (A)", 2D) = "white" {}
    _BumpMap ("Bumpmap (RGB)", 2D) = "bump" {}
}

Category {
    Tags { "RenderType"="Opaque" }
    LOD 400
    Blend AppSrcAdd AppDstAdd
    Fog { Color [_AddFog] }

    SubShader {

        Pass { // This pass renders the texture along with the ambient term.
            Name "BaseColor"
            Tags {"LightMode" = "PixelOrNone"}
            Lighting Off
CGPROGRAM
#pragma fragment frag
#pragma fragmentoption ARB_fog_exp2
#pragma fragmentoption ARB_precision_hint_fastest
#pragma multi_compile_builtin
 
#include "UnityCG.cginc"
#include "AutoLight.cginc"

uniform sampler2D _MainTex;
uniform float4 _Color;

/* Insert your own frag program here but take note to add the ambient term */
float4 frag (v2f_vertex_lit i) : COLOR
{
    // VertexLight is a macro from UnityCG.cginc
    float4 litColor = VertexLight(i, _MainTex); 
    // _PPLAmbient is a builtin unity cg variable that gives you the ambient color set in your project render settings
    float4 ambient = _PPLAmbient * 2 * _Color; 
    return litColor * ambient;
}
ENDCG
        }

        Pass { // The pixel lighting pass goes here. The following is just copy/pasted from Unity's Bump Diffuse shader
            Name "PPL"
            Tags { "LightMode" = "Pixel" }		
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma multi_compile_builtin
#pragma fragmentoption ARB_fog_exp2
#pragma fragmentoption ARB_precision_hint_fastest
#include "UnityCG.cginc"
#include "AutoLight.cginc"

struct v2f { 
	V2F_POS_FOG;
	LIGHTING_COORDS
	float2	uv;
	float2	uv2;
	float3	lightDirT;
};

uniform float4 _MainTex_ST, _BumpMap_ST;

v2f vert (appdata_tan v)
{
	v2f o;
	PositionFog( v.vertex, o.pos, o.fog );
	o.uv = TRANSFORM_TEX(v.texcoord,_MainTex);
	o.uv2 = TRANSFORM_TEX(v.texcoord,_BumpMap);
	
	TANGENT_SPACE_ROTATION;
	o.lightDirT = mul( rotation, ObjSpaceLightDir( v.vertex ) );	
	
	TRANSFER_VERTEX_TO_FRAGMENT(o);
	return o;
}

uniform sampler2D _BumpMap;
uniform sampler2D _MainTex;

float4 frag (v2f i) : COLOR
{
	float4 texcol = tex2D(_MainTex,i.uv);
	
	// get normal from the normal map
	float3 normal = tex2D(_BumpMap, i.uv2).xyz * 2 - 1;
	
	return DiffuseLight( i.lightDirT, normal, texcol, LIGHT_ATTENUATION(i) );
}
ENDCG  
        }
    }
}