Dual Kawase Up – Fast Blur

Fast blur shader as explained here: https://blog.frost.kiwi/dual-kawase/#dual-kawase-blur

Instructions:

1. Add a ColorRect that spans the whole screen (or at least the area you want to blur).
2. Add this shader to the material.

Other versions:

• Dual Kawase Down: https://godotshaders.com/shader/dual-kawase-down-fast-blur/
• Dual Kawase Up: This shader

Shader code

shader_type canvas_item;


uniform float offset: hint_range(0.0, 10.0);
uniform sampler2D SCREEN_TEXTURE : hint_screen_texture, filter_linear_mipmap;


void fragment() {
	vec2 uv = UV;
	vec2 halfpixel = SCREEN_PIXEL_SIZE / 2.0;
	
	vec4 sum = texture(SCREEN_TEXTURE, uv + vec2(-halfpixel.x * 2.0, 0.0) * offset);
	sum += texture(SCREEN_TEXTURE, uv + vec2(-halfpixel.x, halfpixel.y) * offset) * 2.0;
	sum += texture(SCREEN_TEXTURE, uv + vec2(0.0, halfpixel.y * 2.0) * offset);
	sum += texture(SCREEN_TEXTURE, uv + vec2(halfpixel.x, halfpixel.y) * offset) * 2.0;
	sum += texture(SCREEN_TEXTURE, uv + vec2(halfpixel.x * 2.0, 0.0) * offset);
	sum += texture(SCREEN_TEXTURE, uv + vec2(halfpixel.x, -halfpixel.y) * offset) * 2.0;
	sum += texture(SCREEN_TEXTURE, uv + vec2(0.0, -halfpixel.y * 2.0) * offset);
	sum += texture(SCREEN_TEXTURE, uv + vec2(-halfpixel.x, -halfpixel.y) * offset) * 2.0;

	COLOR = sum / 12.0;
}

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