PS1/PSX PostProcessing

Usage:

  1.  Set up the scene as follows:
    SubViewportContainer -> SubViewport -> Spatial
    where Spatial is your 3D scene.
  2. In the SubViewportContainer  add a new ShaderMaterial
  3. In the ShaderMaterial add a new Shader
  4. Copy the script below into the Shader-Editor.

Documentation

  • enabled: Easy option to switch off the shader.
  • dither_size: Defines the pixel size that is used for dithering
  • dithering: Use the dithering pattern.
  • colors: Amount of colors that will be used.

Hint

This shader is written for Godot 4.

 

Shader code
shader_type canvas_item;

render_mode unshaded;

#define MAXCOLORS 16

uniform bool enabled = true;
uniform bool dithering = true;
uniform int colors : hint_range(1, MAXCOLORS) = 12;
uniform int dither_size: hint_range(1, 8) = 2;

float dithering_pattern(ivec2 fragcoord) {
	const float pattern[] = {
		0.00, 0.50, 0.10, 0.65, 
		0.75, 0.25, 0.90, 0.35, 
		0.20, 0.70, 0.05, 0.50, 
		0.95, 0.40, 0.80, 0.30
	};
	
	int x = fragcoord.x % 4;
	int y = fragcoord.y % 4;
	
	return pattern[y * 4 + x];
}

float reduce_color(float raw, float dither, int depth) {
	float div = 1.0 / float(depth);
	float val = 0.0;
	int i = 0;

	while (i <= MAXCOLORS)
	{
		if (raw > div * (float(i + 1))) {
			i = i + 1;
			continue;
		}

		if (raw * float(depth) - float(i) <= dither * 0.999)
		{
			val = div * float(i);
		} 
		else
		{
			val = div * float(i + 1);
		}
		return val;

		i = i+1;
	}

	return val;
}

void fragment() {
	vec4 raw = texture(TEXTURE, SCREEN_UV);
	ivec2 uv = ivec2(FRAGCOORD.xy / float(dither_size));

	if (enabled == true){
		float dithering_value = 1.0;
		if (dithering)
		{
			dithering_value = dithering_pattern(uv);
		}
		
		COLOR.r = reduce_color(raw.r, (dithering_value - 0.5) * dithering_value + 0.5, colors - 1);
		COLOR.g = reduce_color(raw.g, (dithering_value - 0.5) * dithering_value + 0.5, colors - 1);
		COLOR.b = reduce_color(raw.b, (dithering_value - 0.5) * dithering_value + 0.5, colors - 1);

	} else {
		COLOR.rgb = raw.rgb;
	}
}
Tags
godot4, lowpoly, ps1, psx, retro
The shader code and all code snippets in this post are under CC0 license and can be used freely without the author's permission. Images and videos, and assets depicted in those, do not fall under this license. For more info, see our License terms.

More from Grau

Gameboy Look

PS1/PSX Model

Related shaders

PS1/PSX Model

PSX Shader with Vertex Lighting

PS1 Shader

Subscribe
Notify of
guest

7 Comments
Oldest
Newest Most Voted
Inline Feedbacks
View all comments
davidrodmad
5 months ago

This rules, thank you!

dancovich
4 months ago

The only dithering shader I ever got to work. Thank you very much for this great work.

Norko
Norko
1 month ago

is there a way to use this in 4;3 aspect ratio?

Chipik
Chipik
1 month ago

How to set spatial?

skyth
skyth
16 days ago
Reply to  Chipik

see usage

skyth
skyth
16 days ago
Reply to  Chipik

if you think most canvas item shaders dont work in 3d.. they do. just add colorrect select anchor preset and check top level in visible
it’ll work
btw feel free to ask me questions if you want
tis my discord username “skyth_.”

cortrano
cortrano
27 days ago

Is that possible to use this shader with ColorRect/TextureRect Instead?