add outline shader

shaders/outline.gdshader

@@ -0,0 +1,31 @@
+shader_type canvas_item;
+
+uniform vec4 clr : source_color = vec4(0.0, 0.0, 0.0, 1.0);
+uniform int type : hint_range(0, 2) = 2;
+uniform float thickness = 1.0;
+
+const vec2[8] DIRECTIONS = {
+	vec2(1.0, 0.0),
+	vec2(0.0, 1.0),
+	vec2(-1.0, 0.0),
+	vec2(0.0, -1.0),
+	vec2(1.0, 1.0),
+	vec2(-1.0, 1.0),
+	vec2(-1.0, -1.0),
+	vec2(1.0, -1.0)
+};
+
+float gtz(float input) { return max(0, sign(input)); }
+// returns 1 if input > 0, else 0
+
+float check(sampler2D tex, vec2 from, vec2 size) {
+	float result = 0.0;
+	for (int i = 0; i < 4 * type; i++) {
+		result += texture(tex, from + DIRECTIONS[i] * size * thickness).a;
+	}
+	return gtz(result);
+}
+
+void fragment() {
+	COLOR = mix( COLOR, clr, check(TEXTURE, UV, TEXTURE_PIXEL_SIZE) * (1.0 - gtz(COLOR.a)) );
+}

shaders/outline.gdshader.uid

@@ -0,0 +1 @@
+uid://tydujgmoudjd