Load additional images via //!load directive - closes #4

src/ImageViewport.gd

@@ -4,6 +4,11 @@ extends SubViewport
 
 var image_original_tex: ImageTexture
 var image_result: Image
+var load_uniform_regex: RegEx
+
+func _ready():
+	load_uniform_regex = RegEx.new()
+	load_uniform_regex.compile(r'\/\/!load\s(\w*)\s(.*)')
 
 func set_original_image(image: Image):
 	image_original_tex = ImageTexture.create_from_image(image)
@@ -16,6 +21,14 @@ func update():
 		image_sprite.texture = image_original_tex
 		var mat = ShaderMaterial.new()
 		mat.shader = Globals.shader
+		# load images from //!load directives and apply them to
+		# the material as shader parameters
+		for m in load_uniform_regex.search_all(Globals.shader.code):
+			var u_image = Image.load_from_file(m.strings[2])
+			mat.set_shader_parameter(
+				m.strings[1], # uniform param name
+				ImageTexture.create_from_image(u_image))
+		# assign material
 		image_sprite.material = mat
 		# Get viewport texture
 		await RenderingServer.frame_post_draw # for good measure

src/presets/Presets.gd

@@ -5,7 +5,8 @@ const dir = "res://src/presets/shaders/"
 @onready var presets = {
 	"Empty": load(dir + "empty.gdshader"),
 	"Greyscale": load(dir + "greyscale.gdshader"),
-	"Lowpass": load(dir + "lowpass.gdshader")
+	"Lowpass": load(dir + "lowpass.gdshader"),
+	"Mix": load(dir + "mix.gdshader")
 }
 
 var default_preset: String = "Empty"

src/presets/shaders/mix.gdshader

@@ -0,0 +1,8 @@
+shader_type canvas_item;
+
+//!load img2 ./icon.png
+uniform sampler2D img2: repeat_enable, filter_nearest;
+
+void fragment() {
+	COLOR = mix(COLOR, texture(img2, UV), .5);
+}