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

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) * 4.0;
	sum += texture(SCREEN_TEXTURE, uv - halfpixel.xy * offset);
	sum += texture(SCREEN_TEXTURE, uv + halfpixel.xy * offset);
	sum += texture(SCREEN_TEXTURE, uv + vec2(halfpixel.x, -halfpixel.y) * offset);
	sum += texture(SCREEN_TEXTURE, uv - vec2(halfpixel.x, -halfpixel.y) * offset);

	COLOR = sum / 8.0;
}

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