LICENSE

@@ -1,21 +1,28 @@
-MIT License
+BSD 3-Clause License
 
-Copyright (c) 2024 Julian Müller (ChaoticByte)
+Copyright (c) 2025, Julian Müller (ChaoticByte)
 
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
 
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
 
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

README.md

@@ -74,3 +74,33 @@ void fragment() {
 	COLOR = hsv_offset(COLOR, 0.32, 0.2, 0.0);
 }
 ```
+
+## Commandline interface
+
+You can run Fragmented from the commandline or scripts.
+
+> Note: Headless mode is not supported. Using the commandline interface still opens a window.
+
+### Usage
+
+```
+./Fragmented cmd --shader PATH [--load-image PATH]
+
+  --shader PATH      The path to the shader
+  --output PATH      Where to write the resulting image to
+  --load-image PATH  The path to the image. This will overwrite the
+                     load directive of the shader file (optional)
+
+```
+
+You can also run `./Fragmented cmd help` to show the help message.
+
+#### Examples
+
+```
+./Fragmented cmd --shader ./examples/oklab.gdshader --output ./output.png
+```
+
+```
+./Fragmented cmd --shader ./examples/oklab.gdshader --load-image ~/Pictures/test.png --output ./output.png
+```

examples/blur.gdshader

@@ -0,0 +1,8 @@
+shader_type canvas_item;
+
+//!load ./images/swamp.jpg
+#include "res://shaderlib/blur.gdshaderinc"
+
+void fragment() {
+	COLOR = gaussian_blur(TEXTURE, UV, 48, 24.0);
+}

examples/color_and_pixelate.gdshader

@@ -1,6 +1,6 @@
 shader_type canvas_item;
 
-#include "res://shaderlib/hsv.gdshaderinc"
+#include "res://shaderlib/colorspaces.gdshaderinc"
 #include "res://shaderlib/effects.gdshaderinc"
 
 //!load ./images/swamp.jpg
@@ -8,6 +8,7 @@ shader_type canvas_item;
 void fragment() {
 	COLOR = pixelate(TEXTURE, UV, 200.0);
 	vec4 hsv = rgb2hsv(COLOR);
-	COLOR = hsv_offset(COLOR, 0.65, .42-(hsv.y*.3), -.125);
-	COLOR = hsv_multiply(COLOR, 1.0, 1.0, 1.25);
+	hsv.xyz += vec3(0.65, .42-(hsv.y*.3), -.125);
+	hsv.xyz *= vec3(1.0, 1.0, 1.25);
+	COLOR = hsv2rgb(hsv);
 }

examples/oklab.gdshader

@@ -0,0 +1,12 @@
+shader_type canvas_item;
+
+#include "res://shaderlib/colorspaces.gdshaderinc"
+
+//!load ./images/swamp.jpg
+
+void fragment() {
+	vec4 oklab = rgb2oklab(COLOR);
+	vec4 oklch = oklab2oklch(oklab);
+	oklch.z -= 2.0;
+	COLOR = oklab2rgb(oklch2oklab(oklch));
+}

project.godot

@@ -11,7 +11,7 @@ config_version=5
 [application]
 
 config/name="Fragmented"
-config/version="v6.2"
+config/version="v7.0"
 run/main_scene="res://scenes/main.tscn"
 config/features=PackedStringArray("4.3", "Mobile")
 run/low_processor_mode=true

scenes/main.tscn

@@ -1,7 +1,7 @@
 [gd_scene load_steps=10 format=3 uid="uid://bjah7k4bxo044"]
 
 [ext_resource type="Script" path="res://src/Main.gd" id="1_2625y"]
-[ext_resource type="Script" path="res://src/Compositor.gd" id="2_hvo65"]
+[ext_resource type="Script" path="res://src/ImageCompositor.gd" id="2_4thch"]
 [ext_resource type="Shader" path="res://src/shader/ivd_outline.gdshader" id="3_6xihe"]
 [ext_resource type="Script" path="res://src/ImageViewportDisplay.gd" id="3_n4itb"]
 [ext_resource type="Script" path="res://src/UIWindow.gd" id="6_8k0ha"]
@@ -20,14 +20,7 @@ script = ExtResource("1_2625y")
 
 [node name="Compositor" type="SubViewport" parent="."]
 unique_name_in_owner = true
-disable_3d = true
-transparent_bg = true
-canvas_item_default_texture_filter = 0
-render_target_update_mode = 4
-script = ExtResource("2_hvo65")
-
-[node name="ImageSprite" type="Sprite2D" parent="Compositor"]
-unique_name_in_owner = true
+script = ExtResource("2_4thch")
 
 [node name="ImageViewportDisplay" type="Sprite2D" parent="."]
 unique_name_in_owner = true
@@ -44,6 +37,7 @@ unique_name_in_owner = true
 disable_3d = true
 position = Vector2i(48, 36)
 size = Vector2i(704, 704)
+visible = false
 script = ExtResource("6_8k0ha")
 
 [node name="UserInterfaceContainer" parent="EditorWindow" instance=ExtResource("7_5ci0e")]

shaderlib/blur.gdshaderinc

@@ -0,0 +1,32 @@
+
+/*
+	gaussian_blur adapted from https://godotshaders.com/shader/customizable-gausian-blur/
+	original code by https://godotshaders.com/author/djbob-gaming-yt/
+	maximum radius is 64
+*/
+vec4 gaussian_blur(sampler2D texture, vec2 uv, int radius, float sigma) {
+	vec2 resolution = 1.0 / vec2(textureSize(texture, 0));
+	// calculate kernel
+	float kernel[64];
+	float sum = 0.0;
+	for (int i = 0; i <= radius; i++) {
+		kernel[i] = exp(-0.5 * float(i * i) / (sigma * sigma));
+		sum += i == 0 ? kernel[i] : 2.0 * kernel[i];
+	}
+	for (int i = 0; i <= radius; i++) {
+		kernel[i] /= sum;
+	}
+	//
+	vec4 final_color = vec4(0.0);
+	float total_weight = 0.0;
+	for (int x = -radius; x <= radius; x++) {
+		for (int y = -radius; y <= radius; y++) {
+			float weight = kernel[abs(x)] * kernel[abs(y)];
+			vec2 offset = vec2(float(x), float(y)) * resolution;
+			final_color += texture(texture, uv + offset) * weight;
+			total_weight += weight;
+		}
+	}
+	final_color /= total_weight;
+	return final_color;
+}

shaderlib/colorspaces.gdshaderinc

@@ -0,0 +1,90 @@
+
+/*
+	Color space conversion functions always work with vec4.
+	The fourth value is always alpha.
+*/
+
+#include "res://shaderlib/common.gdshaderinc"
+
+/*
+	rgb2hsv and hsv2rgb functions adapted
+	from https://godotshaders.com/shader/hsv-adjustment/
+	original code by https://godotshaders.com/author/al1-ce/
+*/
+
+// Convert RGB to HSV (hue, saturation, brightness)
+vec4 rgb2hsv(vec4 c) {
+	vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
+	vec4 p = mix(vec4(c.bg, K.wz), vec4(c.gb, K.xy), step(c.b, c.g));
+	vec4 q = mix(vec4(p.xyw, c.r), vec4(c.r, p.yzx), step(p.x, c.r));
+	float d = q.x - min(q.w, q.y);
+	float e = 1.0e-10;
+	return vec4(abs(q.z + (q.w - q.y) / (6.0 * d + e)), d / (q.x + e), q.x, c.a);
+}
+
+// Convert HSV back to RGB (red, green, blue)
+vec4 hsv2rgb(vec4 c) {
+	vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
+	vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
+	vec3 rgb =  c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
+	return vec4(rgb.r, rgb.g, rgb.b, c.a);
+}
+
+/*
+	OkLab and OkLCh
+	For more details on oklab, see
+		- https://bottosson.github.io/posts/oklab/
+		- https://en.wikipedia.org/wiki/Oklab_color_space
+*/
+
+vec4 rgb2oklab(vec4 c) {
+	float l = 0.4122214708f * c.r + 0.5363325363f * c.g + 0.0514459929f * c.b;
+	float m = 0.2119034982f * c.r + 0.6806995451f * c.g + 0.1073969566f * c.b;
+	float s = 0.0883024619f * c.r + 0.2817188376f * c.g + 0.6299787005f * c.b;
+
+	float l_ = cbrt(l);
+	float m_ = cbrt(m);
+	float s_ = cbrt(s);
+
+	return vec4(
+		0.2104542553f*l_ + 0.7936177850f*m_ - 0.0040720468f*s_,
+		1.9779984951f*l_ - 2.4285922050f*m_ + 0.4505937099f*s_,
+		0.0259040371f*l_ + 0.7827717662f*m_ - 0.8086757660f*s_,
+		c.a
+	);
+}
+
+vec4 oklab2rgb(vec4 c) {
+	float l_ = c.x + 0.3963377774f * c.y + 0.2158037573f * c.z;
+	float m_ = c.x - 0.1055613458f * c.y - 0.0638541728f * c.z;
+	float s_ = c.x - 0.0894841775f * c.y - 1.2914855480f * c.z;
+
+	float l = l_*l_*l_;
+	float m = m_*m_*m_;
+	float s = s_*s_*s_;
+
+	return vec4(
+		+4.0767416621f * l - 3.3077115913f * m + 0.2309699292f * s,
+		-1.2684380046f * l + 2.6097574011f * m - 0.3413193965f * s,
+		-0.0041960863f * l - 0.7034186147f * m + 1.7076147010f * s,
+		c.a
+	);
+}
+
+vec4 oklab2oklch(vec4 c) {
+	return vec4(
+		c.x,
+		sqrt((c.y * c.y) + (c.z * c.z)),
+		atan(c.z, c.y),
+		c.a
+	);
+}
+
+vec4 oklch2oklab(vec4 c) {
+	return vec4(
+		c.x,
+		c.y * cos(c.z),
+		c.y * sin(c.z),
+		c.a
+	);
+}

shaderlib/common.gdshaderinc

@@ -0,0 +1,5 @@
+
+// inefficient cuberoot function
+float cbrt(float x) {
+	return pow(x, 1.0/3.0);
+}

shaderlib/denoise.gdshaderinc

@@ -1,32 +1,34 @@
 
-/* glslSmartDenoise by Michele Morrone, adapted
-original code: https://github.com/BrutPitt/glslSmartDeNoise
-license of the original code:
-BSD 2-Clause License
+/*
+	glslSmartDenoise by Michele Morrone, adapted
+	original code: https://github.com/BrutPitt/glslSmartDeNoise
+	license of the original code:
 
-Copyright (c) 2019-2020 Michele Morrone
-All rights reserved.
+	BSD 2-Clause License
 
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are met:
+	Copyright (c) 2019-2020 Michele Morrone
+	All rights reserved.
 
-1. Redistributions of source code must retain the above copyright notice, this
+	Redistribution and use in source and binary forms, with or without
+	modification, are permitted provided that the following conditions are met:
+
+	1. Redistributions of source code must retain the above copyright notice, this
 	   list of conditions and the following disclaimer.
 
-2. Redistributions in binary form must reproduce the above copyright notice,
+	2. Redistributions in binary form must reproduce the above copyright notice,
 	   this list of conditions and the following disclaimer in the documentation
 	   and/or other materials provided with the distribution.
 
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
-AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
-IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
-DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
-FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
-DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
-SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
-CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
-OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+	AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+	IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+	DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+	FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+	DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+	SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+	CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+	OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+	OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
 #define INV_SQRT_OF_2PI 0.39894228040143267793994605993439  // 1.0/SQRT_OF_2PI

shaderlib/hsv.gdshaderinc

@@ -1,50 +0,0 @@
-
-// rgb2hsv and hsv2rgb functions adapted
-// from https://godotshaders.com/shader/hsv-adjustment/
-// original code by https://godotshaders.com/author/al1-ce/
-
-// Convert RGB to HSV (hue, saturation, brightness)
-vec4 rgb2hsv(vec4 c) {
-	vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
-	vec4 p = mix(vec4(c.bg, K.wz), vec4(c.gb, K.xy), step(c.b, c.g));
-	vec4 q = mix(vec4(p.xyw, c.r), vec4(c.r, p.yzx), step(p.x, c.r));
-	float d = q.x - min(q.w, q.y);
-	float e = 1.0e-10;
-	return vec4(abs(q.z + (q.w - q.y) / (6.0 * d + e)), d / (q.x + e), q.x, c.a);
-}
-
-// Convert HSV back to RGB (red, green, blue)
-vec4 hsv2rgb(vec4 c) {
-	vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
-	vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
-	vec3 rgb =  c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
-	return vec4(rgb.r, rgb.g, rgb.b, c.a);
-}
-
-// Offset the hue, saturation and brightness of a RGB color
-vec4 hsv_offset(
-	vec4 rgba,
-	float offset_hue,
-	float offset_saturation,
-	float offset_brightness
-) {
-	vec4 c = rgb2hsv(rgba);
-	c.x += offset_hue;
-	c.y += offset_saturation;
-	c.z += offset_brightness;
-	return hsv2rgb(c);
-}
-
-// Multiply the hue, saturation and brightness of a RGB color
-vec4 hsv_multiply(
-	vec4 rgba,
-	float mult_hue,
-	float mult_saturation,
-	float mult_brightness
-) {
-	vec4 c = rgb2hsv(rgba);
-	c.x *= mult_hue;
-	c.y *= mult_saturation;
-	c.z *= mult_brightness;
-	return hsv2rgb(c);
-}

shaderlib/transform.gdshaderinc

@@ -1,6 +1,8 @@
 
-// Load in a texture from a sampler2D with an offset and scale
-// See examples/place_texture.gdshader
+/*
+	Load in a texture from a sampler2D with an offset and scale
+	See examples/place_texture.gdshader
+*/
 vec4 place_texture(sampler2D sampler, vec2 uv, vec2 texture_pixel_size, vec2 offset, vec2 scale) {
 	vec2 texture_size = vec2(textureSize(sampler, 0));
 	// position of current pixel; sample color c

shaderlib/transparency.gdshaderinc

@@ -1,6 +1,8 @@
 
-// Alpha Blending a over b after Bruce A. Wallace
-// source: https://en.wikipedia.org/wiki/Alpha_compositing
+/*
+	Alpha Blending a over b after Bruce A. Wallace
+	source: https://en.wikipedia.org/wiki/Alpha_compositing
+*/
 vec4 alpha_blend(vec4 b, vec4 a) {
 	float alpha = a.a + (b.a * (1.0 - a.a));
 	vec3 col = ((a.rgb*a.a) + ((b.rgb*b.a) * (1.0 - a.a)) / alpha);

src/Editor.gd

@@ -129,18 +129,20 @@ const gdshader_preprocessor = [
 ]
 # shaderlib
 var shaderlib_regex = {
-	"hsv": RegEx.create_from_string(r'\s*\#include\s+\"res\:\/\/shaderlib\/hsv\.gdshaderinc\"'),
+	"colorspaces": RegEx.create_from_string(r'\s*\#include\s+\"res\:\/\/shaderlib\/colorspaces\.gdshaderinc\"'),
 	"transform": RegEx.create_from_string(r'\s*\#include\s+\"res\:\/\/shaderlib\/transform\.gdshaderinc\"'),
 	"transparency": RegEx.create_from_string(r'\s*\#include\s+\"res\:\/\/shaderlib\/transparency\.gdshaderinc\"'),
 	"effects": RegEx.create_from_string(r'\s*\#include\s+\"res\:\/\/shaderlib\/effects\.gdshaderinc\"'),
-	"denoise": RegEx.create_from_string(r'\s*\#include\s+\"res\:\/\/shaderlib\/denoise\.gdshaderinc\"')
+	"denoise": RegEx.create_from_string(r'\s*\#include\s+\"res\:\/\/shaderlib\/denoise\.gdshaderinc\"'),
+	"blur": RegEx.create_from_string(r'\s*\#include\s+\"res\:\/\/shaderlib\/blur\.gdshaderinc\"'),
 }
 const shaderlib_functions = {
-	"hsv": ["rgb2hsv", "hsv2rgb", "hsv_offset", "hsv_multiply"],
+	"colorspaces": ["rgb2hsv", "hsv2rgb", "oklab2rgb", "rgb2oklab", "oklab2oklch", "oklch2oklab"],
 	"transform": ["place_texture"],
 	"transparency": ["alpha_blend"],
 	"effects": ["pixelate"],
-	"denoise": ["smart_denoise"]
+	"denoise": ["smart_denoise"],
+	"blur": ["gaussian_blur"],
 }
 #
 # configure Highlighter

src/ImageCompositor.gd

@@ -1,9 +1,22 @@
-extends SubViewport
+class_name ImageCompositor extends SubViewport
+
+var image_sprite: Sprite2D
+
+func _init() -> void:
+	# Overwrite some variables
+	self.render_target_update_mode = SubViewport.UPDATE_ALWAYS
+	self.disable_3d = true
+	self.transparent_bg = true
+	self.canvas_item_default_texture_filter = Viewport.DEFAULT_CANVAS_ITEM_TEXTURE_FILTER_NEAREST
+	self.image_sprite = Sprite2D.new()
 
 @onready var camera = %Camera
-@onready var image_sprite = %ImageSprite
 @onready var image_viewport_display = %ImageViewportDisplay
 
+func _ready() -> void:
+	# Add image sprite as child to be rendered
+	self.add_child(image_sprite)
+
 var _fragment_function_regex: RegEx = RegEx.create_from_string(r'\s*void\s+fragment\s*\(\s*\)\s*{\s*')
 
 func validate_shader_compilation(shader: Shader) -> bool:
@@ -31,7 +44,7 @@ func inject_step_uniform(shader_code: String) -> Shader:
 	shader.code = shader_code.insert(fragment_function_match.get_start(), "\nuniform int STEP;")
 	return shader
 
-func update() -> Array: # returns error messages (strings)
+func update(overwrite_image_path: String = "") -> Array: # returns error messages (strings)
 	# inject STEP uniform & get number of steps
 	var shader: Shader = inject_step_uniform(Filesystem.shader_code)
 	var steps: int = ShaderDirectiveParser.parse_steps_directive(shader.code)
@@ -40,11 +53,15 @@ func update() -> Array: # returns error messages (strings)
 		return ["Shader compilation failed!"]
 	var errors = []
 	# load texture(s) from //!load directive -> TEXTURE
+	var original_image_path = ""
+	if overwrite_image_path == "":
 		var m = ShaderDirectiveParser.parse_load_directive(shader.code)
 		if len(m) < 1:
 			errors.append("Didn't find a load directive!")
 			return errors
-	var original_image_path = Filesystem.get_absolute_path(m[1])
+		original_image_path = Filesystem.get_absolute_path(m[1])
+	else:
+		original_image_path = overwrite_image_path
 	var fit_image = false
 	if original_image_path != Filesystem.last_original_image_path:
 		fit_image = true

src/Main.gd

@@ -4,7 +4,54 @@ extends Node
 @onready var ui_container = %UserInterfaceContainer
 @onready var app_name = ProjectSettings.get_setting("application/config/name")
 
+func show_help():
+	print(
+		"Usage:\n\n",
+		"./Fragmented cmd --shader PATH [--load-image PATH]\n\n",
+		"  --shader PATH      The path to the shader\n",
+		"  --output PATH      Where to write the resulting image to\n",
+		"  --load-image PATH  The path to the image. This will overwrite the\n",
+		"                     load directive of the shader file (optional)\n")
+
+func parse_custom_cmdline(args: PackedStringArray):
+	var kwargs: Dictionary = {"--shader": null, "--output": null, "--load-image": null}
+	var args_len = args.size()
+	var i = 0
+	while i < args_len:
+		var a = args[i]
+		if a in kwargs && args_len > i+1:
+			i += 1
+			kwargs[a] = args[i]
+		i += 1
+	return kwargs
+
 func _ready():
+	var args = OS.get_cmdline_args()
+	if "cmd" in args: # commandline interface
+		if "help" in args:
+			show_help()
+			get_tree().quit(1)
+		else:
+			var kwargs: Dictionary = parse_custom_cmdline(args)
+			if kwargs["--shader"] == null or kwargs["--output"] == null:
+				show_help()
+				get_tree().quit(1)
+			else:
+				Filesystem.load_shader(kwargs["--shader"])
+				var errors = []
+				if kwargs["--load-image"] == null:
+					errors = await $Compositor.update()
+				else:
+					errors = await $Compositor.update(kwargs["--load-image"])
+				if errors.size() > 0:
+					print("One or more errors occurred.")
+					for e in errors:
+						printerr(e)
+					get_tree().quit(1)
+				else:
+					Filesystem.save_result(kwargs["--output"])
+					get_tree().quit(0)
+	else:
 		update_title()
 		# position windows
 		get_window().position = Vector2i(
@@ -12,6 +59,7 @@ func _ready():
 			editor_window.position.y)
 		get_window().min_size = Vector2i(400, 400)
 		editor_window.min_size = Vector2i(560, 400)
+		editor_window.show()
 		# Load last opened file
 		Filesystem.remember_last_opened_file()
 		if Filesystem.last_shader_savepath != "":