Transparent Solid Color Shader

Question

Hi,

I know nothing of making shaders in Unity, and I’m trying to make a Solid Color shader which is transparent. I currently have the following, which works:

Properties
{
    _Color ("Color", Color) = (1,1,1,.5)
}
SubShader
{
    Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}
    LOD 100
 
    ZWrite On
    Blend SrcAlpha OneMinusSrcAlpha 
 
    Pass
    {
         Lighting Off
         Color [_Color]
    }
}

The problem is though that you can see parts of the model itself that are behind it:

Anyone knows how to fix this? I need/want a solid color, without those bright spots.

Thanks for the help!

Hypothesize

Answer 1

Shader below is do what you want. But your platform should support GrabPass technology. this can be not supported by some mobile platforms.

i can propound 2 more ways without grabpass:

• create a 2-pass shader that first draws only to alpha-channel and the second draws just color based on alpha value, this can be achieved by blending options
• create a object mask using render-texture and put it to main camera on top. this way is same as previous but uses render texture instead of shader calculations and blending

anyway issue is not so simple. with a just default blending two surfaces will be drawn twice and it will look not same as single surface.

shader

Shader "Unity Answers/Solid Transparency Color"
{
	Properties 
	{
		_Color ("Color", Color) = (0.5, 0.5, 0.5, 0.5)
	}
	SubShader
	{
		Tags {"Queue" = "Transparent"}
		ZWrite Off
                GrabPass { }
		Pass
		{
			Fog { Mode Off }
			Blend SrcAlpha OneMinusSrcAlpha

			CGPROGRAM

			#pragma vertex vert
			#pragma fragment frag
	
			fixed4 _Color;
			sampler2D _GrabTexture;

			struct appdata
			{
				float4 vertex : POSITION;
			};
			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 = o.pos;
				return o;
			}
			half4 frag(v2f i) : COLOR
			{
				float2 coord = 0.5 + 0.5 * i.uv.xy / i.uv.w;
				fixed4 tex = tex2D(_GrabTexture, float2(coord.x, 1 - coord.y));
				return fixed4(lerp(tex.rgb, _Color.rgb, _Color.a), 1);
			}
			ENDCG
		}
	}
}

Harlandharle

Thanks! I get an error "No subshader can run on this graphics card" though. Any idea? I'm using Unity Indie, can this be a problem?

– Hypothesize

AFAIK shaders are not depends on Unity license. so this is a hardware limits. which hardware do you use? graphic adapter model? and try menu "edit -> graphic emulation" - does it affect shader? which modes? i think GrabPass{} can be not supported y some cards

– Harlandharle

I currently have a Nvidia 460gtx. I already tried changing the graphic emulation, though that didn't change anything (currently it's at none.) And what do you mean by "which modes" ? Btw, thanks a lot for helping.

– Hypothesize

that's very strange. shader model 2.0 support must be enough to run this shader. your card supports up to shader model 5.0. did you edit this shader? try to use it as is. also, try to switch to fantastic mode in quality settings. if it still doesn't work, try to remove 'GrabPass {}' line. shader will not work properly then, but should draw an object (without transparency). it should help to detect what's wrong in shader. write response here.

– Harlandharle

Ok I tried all what you said. Changing the quality settings doesn't do anything. Removing the GrabPass removes the error, though as you said it's not transparant.

– Hypothesize

Answer 2

This is an old question, but I implemented the two pass shader (with texturing) suggested by @Harlandharle and it works great. This was tested on Unity 4 and the vertex/fragment shaders were based on the samples from the Unity docs here.

The secret ShaderLab sauce is ColorMask and Blend, as seen on the stoned dino below. Enjoy! =)

69348-before.png700×670 354 KB

69349-after.png700×670 364 KB

Shader "Custom/FlatTransparent" {
	Properties {
		_Color("Main Color", Color) = (1,1,1,1)
		_MainTex("Base (RGB) Trans (A)", 2D) = "white" {}
	}

	SubShader {
		Tags{ "Queue" = "Transparent" "IgnoreProjector" = "False" "RenderType" = "Transparent" }

		/////////////////////////////////////////////////////////
		/// First Pass
		/////////////////////////////////////////////////////////

		Pass {
			// Only render alpha channel
			ColorMask A
			Blend SrcAlpha OneMinusSrcAlpha

			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag

			fixed4 _Color;

			float4 vert(float4 vertex : POSITION) : SV_POSITION {
				return mul(UNITY_MATRIX_MVP, vertex);
			}

			fixed4 frag() : SV_Target {
				return _Color;
			}

			ENDCG
		}

		/////////////////////////////////////////////////////////
		/// Second Pass
		/////////////////////////////////////////////////////////

		Pass {
			// Now render color channel
			ColorMask RGB
			Blend SrcAlpha OneMinusSrcAlpha

			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag

			sampler2D _MainTex;
			fixed4 _Color;

			struct appdata {
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

			struct v2f {
				float2 uv : TEXCOORD0;
				float4 vertex : SV_POSITION;
			};

			v2f vert(appdata v) {
				v2f o;
				o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
				o.uv = v.uv;
				return o;
			}

			fixed4 frag(v2f i) : SV_Target{
				fixed4 col = _Color * tex2D(_MainTex, i.uv);
				return col;
			}
			ENDCG
		}
	}

	Fallback "Diffuse"
}

Corves

Quick heads up to future readers: This method works well with a single mesh, but doesn't work with a model that's made up of multiple meshes.

– Noam

I also found another solution posted here: http://wiki.unity3d.com/index.php?title=AlphaVertexLitZ. Is there any advantages to using @ScroodgeM's approach compared to first rendering only into the depth buffer? Is this basically the same thing? Is one faster than the other?

– Abramson

Answer 3

Hello,
I am trying to achieve exactly this effect in my URP project. Neither of the two shaders work in my environment. Is there a solution for current Unity version?
Thanks , Jan

Puente

It might be better to create a new thread for this question and link this thread there.

– Kapoor