Alpha blend

Qimiu October 4, 2024October 4, 2024

I found that I couldn’t find a suitable transparent blending algorithm, so I made one by myself.

The core part of this shader is the following function. You can copy and use it.

vec4 alpha_blend(vec4 o,vec4 n){
	float sum = n.a + o.a;
	sum = clamp(sum,0.0001,1.0);
	float rate = n.a / sum;
	vec4 res = mix(o,n,rate);
	res.a = clamp(n.a+o.a,0.0,1.0);
	return res;
}

Shader code

shader_type canvas_item;

uniform sampler2D pic;

vec4 alpha_blend(vec4 o,vec4 n){
	float sum = n.a + o.a;
	sum = clamp(sum,0.0001,1.0);
	float rate = n.a / sum;
	vec4 res = mix(o,n,rate);
	res.a = clamp(n.a+o.a,0.0,1.0);
	return res;
}


void fragment() {
	COLOR = alpha_blend(COLOR,texture(pic,mod(UV,1.0)));
}