Pixel Perfect outline Shader

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Same outline size from any distance, perfect for interactable objects.
Mode for Godot 4.

To use in Godot 3 replace “source_color” with “hint_color”

Shader code

shader_type spatial;
render_mode cull_front, unshaded;

uniform vec4 outline_color : source_color;
uniform float outline_width = 1.0;

void vertex() {
	vec4 clip_position = PROJECTION_MATRIX * (MODELVIEW_MATRIX * vec4(VERTEX, 1.0));
	vec3 clip_normal = mat3(PROJECTION_MATRIX) * (mat3(MODELVIEW_MATRIX) * NORMAL);
	
	vec2 offset = normalize(clip_normal.xy) / VIEWPORT_SIZE * clip_position.w * outline_width * 2.0;
	
	clip_position.xy += offset;
	
	POSITION = clip_position;
}

void fragment() {
	ALBEDO = outline_color.rgb;
	if (outline_color.a < 1.0) {
		ALPHA = outline_color.a;
	}
}

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