Created a new outline shader.

Instead of changing the albedo of a mesh depending on it's normal
vector at a particular pixel, a new mesh is now created within the
shader that is a slightly expanded version of the original mesh, with
front face culling as to not draw over the original.

This makes the highlighting of certain objects, e.g. cards, more
consistent.

game/Scripts/Game/Pieces/Piece.gd

@@ -421,7 +421,7 @@ puppet func ss(basis0: Basis, basis1: Basis) -> void:
 # color: The color of the outline.
 func set_outline_color(color: Color) -> void:
 	if _outline_material:
-		_outline_material.set_shader_param("Color", color)
+		_outline_material.set_shader_param("OutlineColor", color)
 	else:
 		push_error("Outline material has not been created!")
 
@@ -453,11 +453,11 @@ remotesync func set_translation(new_translation: Vector3) -> void:
 
 # Add the outline material to all mesh instances in this piece.
 func setup_outline_material():
-	var outline_shader = preload("res://Shaders/OutlineShader.tres")
+	var outline_shader = preload("res://Shaders/OutlineShader.shader")
 	
 	_outline_material = ShaderMaterial.new()
 	_outline_material.shader = outline_shader
-	_outline_material.set_shader_param("Color", Color.transparent)
+	_outline_material.set_shader_param("OutlineColor", Color.transparent)
 	
 	for mesh_instance in get_mesh_instances():
 		if mesh_instance is MeshInstance:

game/Scripts/Game/Pieces/Stack.gd

@@ -435,11 +435,11 @@ remotesync func set_piece_order(_order: Array) -> void:
 
 # Add the outline material to the outline mesh instance.
 func setup_outline_material():
-	var outline_shader = preload("res://Shaders/OutlineShader.tres")
+	var outline_shader = preload("res://Shaders/OutlineShader.shader")
 	
 	_outline_material = ShaderMaterial.new()
 	_outline_material.shader = outline_shader
-	_outline_material.set_shader_param("Color", Color.transparent)
+	_outline_material.set_shader_param("OutlineColor", Color.transparent)
 	
 	get_outline_mesh_instance().set_surface_material(0, _outline_material)
 

game/Shaders/OutlineShader.shader

@@ -0,0 +1,24 @@
+// This shader is based off code uploaded by axilirate on Godot Shaders (CC0):
+// https://godotshaders.com/shader/pixel-perfect-outline-shader/
+
+shader_type spatial;
+render_mode cull_front, unshaded;
+
+uniform vec4 OutlineColor: hint_color;
+uniform float OutlineWidth = 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 * OutlineWidth * 2.0;
+	
+	clip_position.xy += offset;
+	
+	POSITION = clip_position;
+}
+
+void fragment() {
+	ALBEDO = OutlineColor.rgb;
+	ALPHA = OutlineColor.a;
+}

game/Shaders/OutlineShader.tres

@@ -1,72 +0,0 @@
-[gd_resource type="VisualShader" load_steps=6 format=2]
-
-[sub_resource type="VisualShaderNodeFresnel" id=1]
-default_input_values = [ 2, false, 3, 3.0 ]
-
-[sub_resource type="VisualShaderNodeColorUniform" id=2]
-uniform_name = "Color"
-
-[sub_resource type="VisualShaderNodeScalarOp" id=3]
-operator = 2
-
-[sub_resource type="VisualShaderNodeInput" id=4]
-input_name = "normal"
-
-[sub_resource type="VisualShaderNodeInput" id=5]
-input_name = "view"
-
-[resource]
-code = "shader_type spatial;
-render_mode specular_schlick_ggx;
-
-uniform vec4 Color : hint_color;
-
-
-
-void vertex() {
-// Output:0
-
-}
-
-void fragment() {
-// ColorUniform:3
-	vec3 n_out3p0 = Color.rgb;
-	float n_out3p1 = Color.a;
-
-// Input:5
-	vec3 n_out5p0 = NORMAL;
-
-// Input:6
-	vec3 n_out6p0 = VIEW;
-
-// Fresnel:2
-	float n_in2p3 = 3.00000;
-	float n_out2p0 = pow(1.0 - clamp(dot(n_out5p0, n_out6p0), 0.0, 1.0), n_in2p3);
-
-// ScalarOp:4
-	float n_out4p0 = n_out3p1 * n_out2p0;
-
-// Output:0
-	ALBEDO = n_out3p0;
-	ALPHA = n_out4p0;
-	EMISSION = n_out3p0;
-
-}
-
-void light() {
-// Output:0
-
-}
-"
-graph_offset = Vector2( -481, 115 )
-nodes/fragment/2/node = SubResource( 1 )
-nodes/fragment/2/position = Vector2( -40, 340 )
-nodes/fragment/3/node = SubResource( 2 )
-nodes/fragment/3/position = Vector2( -40, 160 )
-nodes/fragment/4/node = SubResource( 3 )
-nodes/fragment/4/position = Vector2( 200, 300 )
-nodes/fragment/5/node = SubResource( 4 )
-nodes/fragment/5/position = Vector2( -240, 320 )
-nodes/fragment/6/node = SubResource( 5 )
-nodes/fragment/6/position = Vector2( -240, 380 )
-nodes/fragment/connections = PoolIntArray( 3, 0, 0, 0, 2, 0, 4, 1, 3, 1, 4, 0, 4, 0, 0, 1, 5, 0, 2, 0, 6, 0, 2, 1, 3, 0, 0, 5 )