Additive Blend Unity

2024-11-12 18:05 UTC gpt-4o Open in ChatGPT ↗

To create an additive blend in Unity, you should use the following blend function instead of Blend SrcAlpha OneMinusSrcAlpha:

Blend One One

Explanation of the blend factors:

One refers to multiplying the color by 1, which keeps the original color unchanged.
When you use Blend One One, the colors of your source and destination are added together, producing an additive blend effect.

Here’s how to use it in a shader:

Shader "Custom/AdditiveBlendShader" {
    SubShader {
        Tags { "Queue"="Transparent" }
        Blend One One
        Pass {
            // Your shader code here
        }
    }
}

This will produce an additive blend effect where overlapping colors become brighter. If you want to retain transparency control, you can modify it further using an alpha component. But for a basic additive blend, Blend One One is what you typically use.

To add a color property in a Unity shader, you can extend your Properties block by introducing a color property. Here is how you can modify your existing properties to add a color property:

Properties {
    _MainTex ("Base (RGB) Trans (A)", 2D) = "white" {}
    _Alpha ("Alpha", Range(0,1)) = 0.5
    _Color ("Color Tint", Color) = (1,1,1,1)
}

Explanation:

_Color is the name of the new color property.
"Color Tint" is the label that will appear in the Unity Inspector for the material.
Color is the type, which indicates it’s a color property.
(1,1,1,1) is the default RGBA value for the color (white with full opacity).

To use this color property within the shader code, you can access it like any other property. For example, in a fragment shader:

fixed4 col = tex2D(_MainTex, i.uv) * _Color;
col.a *= _Alpha; // If you want to apply the alpha value as well
return col;

This setup allows you to control the color tint of your shader through the Unity Inspector, and the alpha channel can also be used as desired.

To sample a texture as a 32x32 image using point sampling mode for a “mosaic” effect, you need to adjust the UV coordinates such that they align with a grid of 32x32 cells. Here’s how you can modify your code to achieve this:

// Assume _MainTex_TexelSize is provided automatically by Unity for your texture
float2 texelSize = _MainTex_TexelSize.xy;

// Calculate the size of each "tile" in UV coordinates based on the target size of 32x32 pixels
float2 mosaicSize = float2(1.0 / 32.0, 1.0 / 32.0);

// Snap the UV coordinates to the mosaic grid
float2 mosaicUV = floor(i.uv / mosaicSize) * mosaicSize;

// Sample the texture with adjusted UV coordinates using point sampling
fixed4 sdf = tex2D(_MainTex, mosaicUV);

Explanation:

Mosaic Size Calculation:
- float2 mosaicSize = float2(1.0 / 32.0, 1.0 / 32.0); defines the size of each “tile” in UV space, assuming you want a 32x32 grid over the texture.
Snap UV Coordinates:
- float2 mosaicUV = floor(i.uv / mosaicSize) * mosaicSize; snaps the UV coordinates to the nearest grid position, effectively creating a mosaic effect by making large blocks of pixels have the same UV sample point.
Sampling:
- tex2D(_MainTex, mosaicUV); samples the texture using the modified UVs.

Ensuring Point Sampling

Make sure your texture is set to use point filtering in the Unity Inspector (no interpolation) to maintain the sharp pixelated look of the “mosaic” effect. This can be done by:

Selecting the texture in the Project window.
Setting the Filter Mode to Point (no filter) in the Texture Import Settings.