Its a projector, its not the fastest, but it looks good. Its blend equation is set right now to multiply. That's fine but:
Multiply darkens the blend, making it hard to see in dark places. So, I try an additive blend:
So that looks better. Only it does the opposite: in bright areas, its hard to see:
More so in very bright areas:
So in the end, I am forced to use a normal alpha-blend equation. It looks plain, but is sure to be visible in both bright and dark areas:
Unfortunately, you can't emulate the blend types in Photoshop like Overlay, because blending equations in videocards are fixed-function.
Here's the Unity shaderlab code for alpha-blended projectors:
Shader "Projector/Diffuse" {
Properties {
_Color ("Main Color", Color) = (1,1,1,1)
_ShadowTex ("Cookie", 2D) = "" { TexGen ObjectLinear }
}
Subshader {
Tags { "RenderType"="Transparent" "Queue"="Transparent"}
Pass {
ZWrite off
Fog { Color (0, 0, 0) }
Color [_Color]
ColorMask RGB
Offset -1, -1
Blend SrcAlpha OneMinusSrcAlpha
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma fragmentoption ARB_fog_exp2
#pragma fragmentoption ARB_precision_hint_fastest
#include "UnityCG.cginc"
sampler2D _ShadowTex;
float4x4 _Projector;
fixed4 _Color;
struct v2f {
float4 vertex : SV_POSITION;
float4 texcoord : TEXCOORD0;
};
v2f vert (appdata_tan v)
{
v2f o;
o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
o.texcoord = mul(_Projector, v.vertex);
return o;
}
half4 frag (v2f i) : COLOR
{
return tex2Dproj(_ShadowTex, UNITY_PROJ_COORD(i.texcoord)) * _Color;
}
ENDCG
}
}
}
