texture swap shader

source/funkin/graphics/shaders/TextureSwap.hx

@@ -0,0 +1,48 @@
+package funkin.graphics.shaders;
+
+import flixel.system.FlxAssets.FlxShader;
+import flixel.util.FlxColor;
+import openfl.display.BitmapData;
+
+class TextureSwap extends FlxShader
+{
+  public var swappedImage(default, set):BitmapData;
+  public var amount(default, set):Float;
+
+  function set_swappedImage(_bitmapData:BitmapData):BitmapData
+  {
+    image.input = _bitmapData;
+
+    return _bitmapData;
+  }
+
+  function set_amount(val:Float):Float
+  {
+    fadeAmount.value = [val];
+
+    return val;
+  }
+
+  @:glFragmentSource('
+        #pragma header
+
+        uniform sampler2D image;
+        uniform float fadeAmount;
+
+        void main()
+        {
+            vec4 tex = flixel_texture2D(bitmap, openfl_TextureCoordv);
+            vec4 tex2 = flixel_texture2D(image, openfl_TextureCoordv);
+
+            vec4 finalColor = mix(tex, vec4(tex2.rgb, tex.a), fadeAmount);
+
+            gl_FragColor = finalColor;
+        }
+    ')
+  public function new()
+  {
+    super();
+
+    this.amount = 1;
+  }
+}