Hey guys,
I have a custom shader which colorizes sprites and UI images. It works perfectly! I currently have a scroll rect that will display unlocked objects which I am dynamically colorizing so they have the color swap shader.
I discovered that the unity mask does not play nicely with images that use custom materials / shaders. I took the default ui shader and have been dissecting it trying to figure out what bits I need to transfer over to my custom shader so it masks properly. I found a bunch of resources online regarding the stencil related stuff, and transferred all of that over. But there is one line in particular from the unity default ui shader that when I comment it out, the masking doesn’t work there either. So it seems like I need this line, I’m just struggling to make the shader not error out. I’m not very good with shaders.
Here is the unity default ui shader
Shader "UI/Default"
{
Properties
{
[PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
_Color("Tint", Color) = (1,1,1,1)
_StencilComp("Stencil Comparison", Float) = 8
_Stencil("Stencil ID", Float) = 0
_StencilOp("Stencil Operation", Float) = 0
_StencilWriteMask("Stencil Write Mask", Float) = 255
_StencilReadMask("Stencil Read Mask", Float) = 255
_ColorMask("Color Mask", Float) = 15
[Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip("Use Alpha Clip", Float) = 0
}
SubShader
{
Tags
{
"Queue" = "Transparent"
"IgnoreProjector" = "True"
"RenderType" = "Transparent"
"PreviewType" = "Plane"
"CanUseSpriteAtlas" = "True"
}
Stencil
{
Ref[_Stencil]
Comp[_StencilComp]
Pass[_StencilOp]
ReadMask[_StencilReadMask]
WriteMask[_StencilWriteMask]
}
Cull Off
Lighting Off
ZWrite Off
ZTest[unity_GUIZTestMode]
Blend SrcAlpha OneMinusSrcAlpha
ColorMask[_ColorMask]
Pass
{
Name "Default"
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma target 2.0
#include "UnityCG.cginc"
#include "UnityUI.cginc"
#pragma multi_compile_local _ UNITY_UI_CLIP_RECT
#pragma multi_compile_local _ UNITY_UI_ALPHACLIP
struct appdata_t
{
float4 vertex : POSITION;
float4 color : COLOR;
float2 texcoord : TEXCOORD0;
UNITY_VERTEX_INPUT_INSTANCE_ID
};
struct v2f
{
float4 vertex : SV_POSITION;
fixed4 color : COLOR;
float2 texcoord : TEXCOORD0;
float4 worldPosition : TEXCOORD1;
UNITY_VERTEX_OUTPUT_STEREO
};
sampler2D _MainTex;
fixed4 _Color;
fixed4 _TextureSampleAdd;
float4 _ClipRect;
float4 _MainTex_ST;
v2f vert(appdata_t v)
{
v2f OUT;
UNITY_SETUP_INSTANCE_ID(v);
UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
OUT.worldPosition = v.vertex;
OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);
OUT.texcoord = TRANSFORM_TEX(v.texcoord, _MainTex);
OUT.color = v.color * _Color;
return OUT;
}
fixed4 frag(v2f IN) : SV_Target
{
half4 color = (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd) * IN.color;
#ifdef UNITY_UI_CLIP_RECT
color.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);
#endif
#ifdef UNITY_UI_ALPHACLIP
clip(color.a - 0.001);
#endif
return color;
}
ENDCG
}
}
}
Here is the palette swap shader that I’m using:
Shader "Sprites/ColorSwapV3"
{
Properties
{
[PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
_SwapTex("Color Data", 2D) = "transparent" {}
_Color("Tint", Color) = (1,1,1,1)
[MaterialToggle] PixelSnap("Pixel snap", Float) = 0
[HideInInspector] _RendererColor("RendererColor", Color) = (1,1,1,1)
[HideInInspector] _Flip("Flip", Vector) = (1,1,1,1)
[PerRendererData] _AlphaTex("External Alpha", 2D) = "white" {}
[PerRendererData] _EnableExternalAlpha("Enable External Alpha", Float) = 0
_StencilComp("Stencil Comparison", Float) = 8
_Stencil("Stencil ID", Float) = 0
_StencilOp("Stencil Operation", Float) = 0
_StencilWriteMask("Stencil Write Mask", Float) = 255
_StencilReadMask("Stencil Read Mask", Float) = 255
_ColorMask("Color Mask", Float) = 15
[Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip("Use Alpha Clip", Float) = 0
}
SubShader
{
Tags
{
"Queue" = "Transparent"
"IgnoreProjector" = "True"
"RenderType" = "Transparent"
"PreviewType" = "Plane"
"CanUseSpriteAtlas" = "True"
}
Stencil
{
Ref[_Stencil]
Comp[_StencilComp]
Pass[_StencilOp]
ReadMask[_StencilReadMask]
WriteMask[_StencilWriteMask]
}
Cull Off
Lighting Off
ZWrite Off
ZTest[unity_GUIZTestMode]
Blend SrcAlpha OneMinusSrcAlpha
ColorMask[_ColorMask]
Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma target 2.0
#pragma multi_compile_instancing
#pragma multi_compile _ PIXELSNAP_ON
#pragma multi_compile _ ETC1_EXTERNAL_ALPHA
#include "UnitySprites.cginc"
v2f vert(appdata_t IN)
{
v2f OUT;
UNITY_SETUP_INSTANCE_ID(IN);
UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
#ifdef UNITY_INSTANCING_ENABLED
IN.vertex.xy *= _Flip.xy;
#endif
OUT.vertex = UnityObjectToClipPos(IN.vertex);
OUT.texcoord = IN.texcoord;
OUT.color = IN.color * _Color * _RendererColor;
#ifdef PIXELSNAP_ON
OUT.vertex = UnityPixelSnap(OUT.vertex);
#endif
return OUT;
}
sampler2D _SwapTex;
float4 _ClipRect;
fixed4 frag(v2f IN) : SV_Target
{
fixed4 c = SampleSpriteTexture(IN.texcoord);
fixed4 swapCol = tex2D(_SwapTex, float2(c.x, 0));
fixed4 final = lerp(c, swapCol, swapCol.a);
final.a = c.a * IN.color.a;
final.rgb *= final.a * IN.color.rgb;
#ifdef UNITY_UI_CLIP_RECT
c.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);
#endif
#ifdef UNITY_UI_ALPHACLIP
clip(c.a - 0.001);
#endif
return final;
}
ENDCG
}
}
}
The line that makes masking break with unitys default ui shader is:
#ifdef UNITY_UI_CLIP_RECT
c.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);
#endif
I’m not entirely sure if I’m using it right, but it is my only lead at this point! Any suggestions or tips would be greatly appreciated! I am just trying to make the color swap shader work with ui masking 
Thanks guys!
