adding mask options

ui_scenes/selectedSprite/mask.gdshader

@@ -0,0 +1,23 @@
+shader_type canvas_item;
+
+uniform sampler2D mask_texture : source_color;
+uniform bool use_mask = false;
+uniform float mask_opacity : hint_range(0.0, 1.0) = 1.0;
+
+void fragment() {
+	// Get the original sprite color
+	vec4 sprite_color = texture(TEXTURE, UV);
+	
+	if (use_mask) {
+		// Sample the mask texture
+		vec4 mask_sample = texture(mask_texture, UV);
+		
+		// Use the mask's alpha channel to determine visibility
+		float mask_alpha = mask_sample.a * mask_opacity;
+		
+		// Apply the mask by multiplying the sprite's alpha with the mask alpha
+		sprite_color.a *= mask_alpha;
+	}
+	
+	COLOR = sprite_color;
+}