How can I make shadows pixelated in fragment function?

Questions & Answers
1

Hello! I’m pretty novice when it comes to graphics programming, so I’d love some advice on the best way to solve this problem. Let me give you some context.

Take a look at this image:

Alt Text

The above image represents how I light a square mesh. The values at the corners of the square represent a lighting value. 1 being fully shadowed, 0 being fully lit. Don’t worry about how I get this value. I put this value into the uv2 channel of the mesh component. So, the bottom left vertex value gets stored as (0.0, 1.0f). I’m not using the x, just y in this case.

On to the shader:

Okay, so, I’m currently using this value in my frag function as a light multiplier. uv *= uv2.y (Remember, I’m only using the y-axis from uv2, it’s the light value!) This creates a nice light blend, as the 1 light value lerps to 0.

Unfortunately, I’m using a pixel art texture that harshly contrasts the lighting gradient. See below:

Alt Text

It may be hard to see, but the pixel art is most apparent at the top right of the image. I want the shadow to have that same look, if possible.

Would it be possible to use the uv coord to snap this light value to a pixel grid?

Here is my current code:

CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#include "UnityCG.cginc"

			struct app_data
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
				float2 uv2 : TEXCOORD1;
			};

			struct v2f
			{
				float4 vertex : SV_POSITION;
				float2 uv : TEXCOORD0;
				float2 uv2 : TEXCOORD1;
			};

			sampler2D _MainTex;
			float4 _MainTex_ST;
              
			v2f vert (app_data v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = v.uv;
				o.uv2 = v.uv2;

				return o;
			}
			
			fixed4 frag (v2f input) : SV_Target
			{
				fixed4 col = tex2D(_MainTex, input.uv);
                col.rgb *= input.uv2.y;
                return col;
			}
			ENDCG

Thanks for any feedback!

2

I am not sure what you want, because i can’t see your image. But to manually render shadow, you need to use LIGHT_ATTENUATION() in AutoLight.cginc. I guess you can make it pixelated by working on the value _ShadowCoord

Edit

Ok i think i get what you want. You are not talking about the shadow of unity lighting system. You are talking about some light data baked in to vertex. Try something like this:

 col.rgb *= round(input.uv2.y*4)/4;

it doesn’t have to be 4