shader_type canvas_item;

uniform bool outline_enabled = false;
uniform vec3 outline_color : source_color = vec3(1.0);

void fragment() {
	COLOR = texture(TEXTURE, UV);

	if (outline_enabled) {
		float border = texture(TEXTURE, UV + vec2(TEXTURE_PIXEL_SIZE.x, 0.0)).a;
		border += texture(TEXTURE, UV - vec2(TEXTURE_PIXEL_SIZE.x, 0.0)).a;
		border += texture(TEXTURE, UV + vec2(0.0, TEXTURE_PIXEL_SIZE.y)).a;
		border += texture(TEXTURE, UV - vec2(0.0, TEXTURE_PIXEL_SIZE.y)).a;
		float final = step(sign(border), sign(COLOR.a));
		COLOR = vec4(vec3(mix(outline_color, COLOR.rgb, final)), step(final, COLOR.a));
	}
}