Implement support for elapsed time in loaded shaders for layer effects

Simply add `uniform float PXO_time;` in the shader's uniforms, and replace all instances of `TIME` with `PXO_time`. This will make the shader animate per frame.

src/Classes/Cels/BaseCel.gd

@@ -24,6 +24,13 @@ func get_final_opacity(layer: BaseLayer) -> float:
 	return layer.opacity * opacity
 
 
+func get_frame(project: Project) -> Frame:
+	for frame in project.frames:
+		if frame.cels.has(self):
+			return frame
+	return null
+
+
 # Methods to Override:
 
 

src/Classes/Layers/BaseLayer.gd

@@ -234,8 +234,10 @@ func display_effects(cel: BaseCel, image_override: Image = null) -> Image:
 	for effect in effects:
 		if not effect.enabled or not is_instance_valid(effect.shader):
 			continue
+		var params := effect.params
+		params["PXO_time"] = cel.get_frame(project).position_in_seconds(project)
 		var shader_image_effect := ShaderImageEffect.new()
-		shader_image_effect.generate_image(image, effect.shader, effect.params, image_size)
+		shader_image_effect.generate_image(image, effect.shader, params, image_size)
 	# Inherit effects from the parents, if their blend mode is set to pass through
 	for ancestor in get_ancestors():
 		if ancestor.blend_mode != BlendModes.PASS_THROUGH:

src/Classes/ShaderLoader.gd

@@ -62,6 +62,8 @@ static func create_ui_for_shader_uniforms(
 		var u_init := u_left_side[0].split(" ")
 		var u_type := u_init[1]
 		var u_name := u_init[2]
+		if u_name == "PXO_time":
+			continue
 		# Find custom data of the uniform, if any exists
 		# Right now it only checks if a uniform should have another type of node
 		# Such as integers having OptionButtons

src/UI/Timeline/LayerEffects/LayerEffectsSettings.gd

@@ -177,8 +177,10 @@ func _apply_effect(layer: BaseLayer, effect: LayerEffect) -> void:
 			undo_data[cel_image.indices_image] = cel_image.indices_image.data
 		undo_data[cel_image] = cel_image.data
 		var image_size := cel_image.get_size()
+		var params := effect.params
+		params["PXO_time"] = frame.position_in_seconds(project)
 		var shader_image_effect := ShaderImageEffect.new()
-		shader_image_effect.generate_image(cel_image, effect.shader, effect.params, image_size)
+		shader_image_effect.generate_image(cel_image, effect.shader, params, image_size)
 
 	var tile_editing_mode := TileSetPanel.tile_editing_mode
 	if tile_editing_mode == TileSetPanel.TileEditingMode.MANUAL: