2D outline stroke

Adds an outer outline stroke to a Sprite texture. Alpha acts as the defining border which the stroke follows. This shader comes from GD Quest’s library of free shaders.

Shader code
shader_type canvas_item;

uniform vec4 line_color : hint_color = vec4(1);
uniform float line_thickness : hint_range(0, 10) = 1.0;

void fragment() {
	vec2 size = TEXTURE_PIXEL_SIZE * line_thickness;
	
	float outline = texture(TEXTURE, UV + vec2(-size.x, 0)).a;
	outline += texture(TEXTURE, UV + vec2(0, size.y)).a;
	outline += texture(TEXTURE, UV + vec2(size.x, 0)).a;
	outline += texture(TEXTURE, UV + vec2(0, -size.y)).a;
	outline += texture(TEXTURE, UV + vec2(-size.x, size.y)).a;
	outline += texture(TEXTURE, UV + vec2(size.x, size.y)).a;
	outline += texture(TEXTURE, UV + vec2(-size.x, -size.y)).a;
	outline += texture(TEXTURE, UV + vec2(size.x, -size.y)).a;
	outline = min(outline, 1.0);
	
	vec4 color = texture(TEXTURE, UV);
	COLOR = mix(color, line_color, outline - color.a);
}
Tags
2d, border, outline, sprite, stroke

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The shader code and all code snippets in this post are under MIT license and can be used freely. Images and videos, and assets depicted in those, do not fall under this license. For more info, see our License terms.
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