Make shape previews look like they did in v1.0

The AutoInvertColors shader has been updated to make shapes hollow, similar to how the marching ants outline works.

src/Shaders/AutoInvertColors.gdshader

@@ -1,13 +1,25 @@
 shader_type canvas_item;
+#include "CanvasCommon.gdshaderinc"
 
 uniform sampler2D screen_texture : hint_screen_texture;
+uniform bool hollow_shapes = true;
 
 void fragment() {
 	vec4 color = texture(TEXTURE, UV);
-	COLOR = color;
 	vec3 inverted = vec3(1.0) - color.rgb;
 	vec3 screen_color = textureLod(screen_texture, SCREEN_UV, 0.0).rgb;
 	float screen_avg = (screen_color.r + screen_color.g + screen_color.b) / 3.0;
 
-	COLOR.rgb = inverted * step(0.5, screen_avg) + color.rgb * step(screen_avg, 0.5);
+	color.rgb = inverted * step(0.5, screen_avg) + color.rgb * step(screen_avg, 0.5);
+	if (hollow_shapes) {
+		if (COLOR.a > 0.0 && has_contrary_neighbour(UV, TEXTURE_PIXEL_SIZE, TEXTURE)) {
+			COLOR = color;
+		}
+		else { // Erase the texture's pixels in order to only keep the outline visible
+			COLOR.a = 0.0;
+		}
+	}
+	else {
+		COLOR = color;
+	}
 }

src/Shaders/CanvasCommon.gdshaderinc

@@ -0,0 +1,24 @@
+uniform float width : hint_range(0, 2) = 0.05;
+
+bool is_zero_approx(float num) {
+	return num < 0.0001;
+}
+
+
+bool has_contrary_neighbour(vec2 uv, vec2 texture_pixel_size, sampler2D tex) {
+	float i = -ceil(width);
+	float j = ceil(width);
+	float x1 = abs(i) > width ? width * sign(i) : i;
+	float x2 = abs(j) > width ? width * sign(j) : j;
+	float y1 = abs(i) > width ? width * sign(i) : i;
+	float y2 = abs(j) > width ? width * sign(j) : j;
+
+	vec2 xy1 = uv + texture_pixel_size * vec2(x1, y1);
+	vec2 xy2 = uv + texture_pixel_size * vec2(x2, y2);
+
+	if (xy1 != clamp(xy1, vec2(0.0), vec2(1.0)) || is_zero_approx(texture(tex, xy1).a) || xy2 != clamp(xy2, vec2(0.0), vec2(1.0)) || is_zero_approx(texture(tex, xy2).a)) {
+		return true;
+	}
+
+	return false;
+}

src/Shaders/MarchingAntsOutline.gdshader

@@ -2,39 +2,15 @@
 // Also thanks to https://andreashackel.de/tech-art/stripes-shader-1/ for the stripe tutorial
 shader_type canvas_item;
 
+#include "CanvasCommon.gdshaderinc"
 uniform vec4 first_color : source_color = vec4(1.0);
 uniform vec4 second_color : source_color = vec4(0.0, 0.0, 0.0, 1.0);
 uniform bool animated = true;
-uniform float width : hint_range(0, 2) = 0.05;
 uniform float frequency = 50.0;
 uniform float stripe_direction : hint_range(0, 1) = 0.5;
 
 
-bool is_zero_approx(float num) {
-	return num < 0.0001;
-}
-
-
-bool has_contrary_neighbour(vec2 uv, vec2 texture_pixel_size, sampler2D tex) {
-	float i = -ceil(width);
-	float j = ceil(width);
-	float x1 = abs(i) > width ? width * sign(i) : i;
-	float x2 = abs(j) > width ? width * sign(j) : j;
-	float y1 = abs(i) > width ? width * sign(i) : i;
-	float y2 = abs(j) > width ? width * sign(j) : j;
-
-	vec2 xy1 = uv + texture_pixel_size * vec2(x1, y1);
-	vec2 xy2 = uv + texture_pixel_size * vec2(x2, y2);
-
-	if (xy1 != clamp(xy1, vec2(0.0), vec2(1.0)) || is_zero_approx(texture(tex, xy1).a) || xy2 != clamp(xy2, vec2(0.0), vec2(1.0)) || is_zero_approx(texture(tex, xy2).a)) {
-		return true;
-	}
-
-	return false;
-}
-
 void fragment() {
-	COLOR = texture(TEXTURE, UV);
 	vec2 ts = TEXTURE_PIXEL_SIZE;
 
 	if (COLOR.a > 0.0 && has_contrary_neighbour(UV, ts, TEXTURE)) {
@@ -47,8 +23,7 @@ void fragment() {
 		float value = floor(fract(pos) + 0.5);
 		COLOR = mix(first_color, second_color, step(1.0, mod(value, 2.0)));
 	}
-	else {
-		// Erase the texture's pixels in order to only keep the outline visible
+	else { // Erase the texture's pixels in order to only keep the outline visible
 		COLOR.a = 0.0;
 	}
 }

src/UI/Canvas/Canvas.tscn

@@ -28,15 +28,17 @@ blend_mode = 4
 
 [sub_resource type="ShaderMaterial" id="2"]
 shader = ExtResource("9")
+shader_parameter/width = 0.05
 shader_parameter/first_color = Color(1, 1, 1, 1)
 shader_parameter/second_color = Color(0, 0, 0, 1)
 shader_parameter/animated = true
-shader_parameter/width = 0.05
 shader_parameter/frequency = 200.0
 shader_parameter/stripe_direction = 0.5
 
 [sub_resource type="ShaderMaterial" id="3"]
 shader = ExtResource("17_lowhf")
+shader_parameter/width = 0.05
+shader_parameter/hollow_shapes = true
 
 [node name="Canvas" type="Node2D"]
 material = SubResource("ShaderMaterial_6b0ox")

src/UI/Canvas/Previews.gd

@@ -1,6 +1,10 @@
 extends Node2D
 
 
+func _ready() -> void:
+	Global.camera.zoom_changed.connect(_update_on_zoom)
+
+
 func _input(event: InputEvent) -> void:
 	if event is InputEventMouse or event is InputEventKey:
 		queue_redraw()
@@ -9,3 +13,7 @@ func _input(event: InputEvent) -> void:
 func _draw() -> void:
 	if Global.can_draw:
 		Tools.draw_preview()
+
+
+func _update_on_zoom() -> void:
+	material.set_shader_parameter("width", 1.0 / Global.camera.zoom.x)