Added underpinnings for advanced screen flash; tweaked default values

for existing screen flash.

scenes/boss.gd

@@ -62,7 +62,7 @@ func boss_horse():
   if heart_taken == false:
     print("Boss horse!")
     await get_tree().create_timer(2).timeout
-    EventBus.flash_screen.emit(.25)
+    EventBus.flash_screen.emit(.15)
     $Heart.hide()
     $Heart.monitoring = false
     $Sprite2D.frame = 7
@@ -71,7 +71,7 @@ func boss_horse():
     var horse_player = $Horse/AnimationPlayer
     horse_player.play("run")
     await get_tree().create_timer(10).timeout
-    EventBus.flash_screen.emit(.25)
+    EventBus.flash_screen.emit(.15)
     $Horse.hide()
     $Horse.end()
     await get_tree().create_timer(5).timeout

scenes/main.gd

@@ -184,7 +184,7 @@ func _on_win_game(value: int):
       start_button.show()
       
     
-func _on_flash_screen(duration: float):
+func _on_flash_screen(duration: float = .25):
     print("flash!")
     $CanvasLayer/ColorRect.visible = true
     await get_tree().create_timer(duration).timeout

scenes/wave.gd

@@ -57,7 +57,7 @@ func spawn_enemies():
       print("Enemy Wave: ", wave_count)
       
       # Spawn Table
-      EventBus.flash_screen.emit(.25)
+      EventBus.flash_screen.emit(.15)
       var t = TABLE.instantiate()
       add_child(t)
       t.position = Vector2(screensize.x / 2, position.y + 125)
@@ -67,7 +67,7 @@ func spawn_enemies():
       ts.play()
       ts = t.get_child(0)
       ts.frame = 1
-      EventBus.flash_screen.emit(.25)
+      EventBus.flash_screen.emit(.15)
       await get_tree().create_timer(1.5).timeout
       
       # Spawn Mirror

shaders/flash_screen.gdshader

@@ -0,0 +1,15 @@
+shader_type canvas_item;
+
+uniform vec4 flash_color : source_color = vec4(1.0, 0.0, 0.0, 1.0); 
+uniform float intensity : hint_range(0.0, 1.0) = 0.0; 
+uniform float edge_power : hint_range(0.1, 4.0) = 2.5; 
+uniform float inner_ratio : hint_range(0.0, 1.0) = 0.75; 
+uniform float feather : hint_range(0.01, 1.0) = 0.4; 
+
+void fragment() { 
+    vec2 uv = UV * 2.0 - 1.0; 
+    float dist = length(uv); 
+    float a = smoothstep(inner_ratio, inner_ratio + feather, dist); 
+    a = pow(a, edge_power); 
+    COLOR = vec4(flash_color.rgb, a * flash_color.a * intensity); 
+}

shaders/flash_screen.gdshader.uid

@@ -0,0 +1 @@
+uid://d1nem2giyx0sy