BlendOp Max in a shader cuts sprites to half-opacity

[Connormcp777]

Hey!

I’m making a 2D game that requires light. I created torches that use point lights and a sprites/diffuse shader for all the sprites’ material.

… Or the USED to use a diffuse shader. The problem with this system is that if two lights are near each other, their intensities COMBINE. The resulting super-bright light washed out all the features of my objects! So I made this new shader:

Code (CSharp):

Shader "Sprites/No-Overlap-Diffuse"
{
    Properties
    {
        [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
        _Color ("Tint", Color) = (1,1,1,1)
        [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
    }
 
    SubShader
    {
        Tags
        {
            "RenderType" = "Opaque"
            "Queue"="Transparent"
            "IgnoreProjector"="True"
            "RenderType"="Transparent"
            "PreviewType"="Plane"
            "CanUseSpriteAtlas"="True"
        }
 
        Cull Off
        Lighting Off
        ZWrite Off
        Blend One OneMinusSrcAlpha
        BlendOp Max
 
        CGPROGRAM
        #pragma surface surf Lambert vertex:vert nofog nolightmap nodynlightmap keepalpha noinstancing
        #pragma multi_compile _ PIXELSNAP_ON
        #pragma multi_compile _ ETC1_EXTERNAL_ALPHA
        #include "UnitySprites.cginc"
 
        struct Input
        {
            float2 uv_MainTex;
            fixed4 color;
        };
 
        void vert (inout appdata_full v, out Input o)
        {
            v.vertex = UnityFlipSprite(v.vertex, _Flip);
 
            UNITY_INITIALIZE_OUTPUT(Input, o);
            o.color = v.color * _Color * _RendererColor;
        }
 
        void surf (Input IN, inout SurfaceOutput o)
        {
            fixed4 c = SampleSpriteTexture (IN.uv_MainTex) * IN.color;
            o.Albedo = c.rgb * c.a;
            o.Alpha = c.a;
        }
        ENDCG
    }
 
Fallback "Transparent/VertexLit"
}

This heavily borrows from the actual sprites/diffuse source code I got from the Unity Archives. The only caveat is that I added the BlendOp max command.

While this did get rid of the overlapping lights problem (=D), it added a NEW problem, which is that it turns all my sprites into GHOSTS! Every pixel on the object gets an opacity directly related to how dark the pixel is: The color white is perfectly solid, but black is completely transparent, while everything else falls somewhere in between.

What is happening!?

[Monstetcat]

Hey, im making a 2D pixel game with unity. I’d like to let player be able to set light by themselves. But when i tring to make this Function i met the same problem there. The lights will overlap!!!
This problem confused me for a really long time, so im start study about UnityShder.
Now im glad to share what i learned.
here is my shader:

Shader "Custom/PerPixelShader" {
	Properties {
		_Diffuse ("Diffuse", Color) = (1,1,1,1)
		_MainTex("Texture",2D) = "white"{}
		_Cutoff("Alpha Cutoff",Range(0,1)) = 0.5

	}
	SubShader {
		Tags{"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="TransparentCutout"}
		//ZWrite Off
		Pass
		{
			Tags{"LightMode" = "ForwardBase"}

			CGPROGRAM 
			#pragma vertex vert
			#pragma fragment frag
			#pragma multi_compile_fwdbase
			#pragma target 3.0 
			#include "UnityCG.cginc" 
			#include "Lighting.cginc" 

			//fixed4 _Diffuse;
			 
 
			struct appdata 
			{
				float4 vertex : POSITION;
				float3 normal : NORMAL;
				float2 uv : TEXCOORD0;
			};

			struct v2f
			{
				float4 vertex : SV_POSITION;
				float3 worldNormal : TEXCOORD0;
				float3 worldPos : TEXCOORD1;
				float2 uv : TEXCOORD2;
			};

			sampler2D _MainTex;
			float4 _MainTex_ST;
			fixed _Cutoff;
 
			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
 
				o.worldNormal = UnityObjectToWorldNormal(v.normal);
				o.worldPos = mul(unity_ObjectToWorld,v.vertex).xyz;
				o.uv = TRANSFORM_TEX(v.uv,_MainTex);

				return o;
			}
 
 
			fixed4 frag (v2f i) : SV_Target
			{
				

				fixed3 worldNormal = normalize(i.worldNormal);

				fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(i.worldPos));

				fixed4 albedo = tex2D(_MainTex,i.uv);

				fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo.rgb;

				clip (albedo.a - _Cutoff);//透明度 
				 
				fixed3 diffuse = _LightColor0.rgb * albedo * max(0,dot(worldNormal,worldLightDir));

				//fixed3 viewDir = normalize(UnityWorldSpaceViewDir(i.worldPos));
				//fixed3 halfDir = normalize(worldLightDir+viewDir);

				//fixed3 color = ambient + diffuse;

				return fixed4(ambient+diffuse,1.0);
			} 
			ENDCG	
		}

		Pass
		{
			Tags{"LightMode" = "ForwardAdd"}

			BlendOp Max


			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#pragma multi_compile_fwdadd
			#pragma target 3.0 
			#include "UnityCG.cginc" 
			#include "Lighting.cginc" 
			#include "AutoLight.cginc"

			struct appdata 
			{
				float4 vertex : POSITION;
				float3 normal : NORMAL;
				float2 uv : TEXCOORD0;
			};

			struct v2f
			{
				float4 vertex : SV_POSITION;
				float3 worldNormal : TEXCOORD0;
				float3 worldPos : TEXCOORD1;
				float2 uv : TEXCOORD2;
			};

			sampler2D _MainTex;
			float4 _MainTex_ST;
			fixed _Cutoff;

 
			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
 
				o.worldNormal = UnityObjectToWorldNormal(v.normal);
				o.worldPos = mul(unity_ObjectToWorld,v.vertex).xyz;
				o.uv = TRANSFORM_TEX(v.uv,_MainTex);

				return o;
			}
 
 
			fixed4 frag (v2f i) : SV_Target
			{
				

				fixed3 worldNormal = normalize(i.worldNormal);
				
				 
			#ifdef USING_DIRECTINAL_LIGHT
				fixed3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz);
				
			#else
				fixed3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz - i.worldPos.xyz);
				
			#endif

				fixed4 albedo = tex2D(_MainTex,i.uv);

				//fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo.rgb;

				clip (albedo.a - _Cutoff);//透明度 
				 
				fixed3 diffuse = _LightColor0.rgb * albedo * max(0,dot(worldNormal,worldLightDir));

				//fixed3 viewDir = normalize(_WorldSpaceCameraPos.xyz - i.worldPos.xyz);
				//fixed3 halfDir = normalize(worldLightDir+viewDir); 

				//fixed3 specular = _LightColor0.rgb * pow(saturate(dot(worldNormal,halfDir)),255);

				//fixed3 color = ambient + diffuse;

				#ifdef USING_DIRECTIONAL_LIGHT
					fixed atten = 1.0;
				#else
					#if defined (POINT)
				        float3 lightCoord = mul(unity_WorldToLight, float4(i.worldPos, 1)).xyz;
				        fixed atten = tex2D(_LightTexture0, dot(lightCoord, lightCoord).rr).UNITY_ATTEN_CHANNEL;

				    #elif defined (SPOT)
				        float4 lightCoord = mul(unity_WorldToLight, float4(i.worldPos, 1));
				        fixed atten = (lightCoord.z > 0) * tex2D(_LightTexture0, lightCoord.xy / lightCoord.w + 0.5).w * tex2D(_LightTextureB0, dot(lightCoord, lightCoord).rr).UNITY_ATTEN_CHANNEL;
						
				    #else
				        fixed atten = 1.0;
				    #endif
				#endif

				return fixed4(diffuse*atten,1.0);
			} 
			ENDCG	
		}
	}

	
	FallBack "Sprite/Diffuse"
}

Unity’s surface shader can’t manualy deal with fwdadd pass(maybe just because i not found the correct way to change it), so i use the Vertx/Fragment Shader,and i change the fwdadd Pass’s blendmode.
But here is some problem still confuse me.

1. I personally recommend use Spot light, although point light has much better effect on 2dgame(the center is brighter than outline),if you use point light there will be a black gap between two point light.
I don’t know how to figure this out. If someone know what cause this pls tell me thanks =D.

2. You must change the all light mode to Important mode(per pixel).
If you need to put light more than 4 in a single scene, u need to change the quality setting and modify the pixel light count to your needed count;
But there also be quality problem here, i have tested that on PC you can put 30+ light in a single scene, based on PC’s hardware level. But on mobile device you can only put at most 8 light.
Now im looking for a new method to achieve what i really want effect and can run perfectly on mobile device.

3. There should be only one directlight in a single scene, the light mode should be important (perpixellight), and the intensity should be 0.85f(1 will be too bright).

4. Be careful about sorting layer and Z pos.

[Connormcp777]

You are a miracle worker! It works perfectly!

This problem has given me so many headaches. Thank you!