Six Channel Colour Shader

A simple shader for colouring static objects dynamically. Contains 6 channels, Red, Magenta, Green, Yellow, Blue, Cyan. Example:

x = any_number>0

  • Red = Color(X,0.0,0.0,1.0)
  • Magenta = Color(X, 0.0,X,1.0)
  • Non shaded colour = Color(X,X,X,1.0)

Can be shaded, so

  • Bright = Color(1.0,0.0,0.0,1.0)
  • Medium = Color(0.5,0.0,0.0,1.0)
  • Dark = Color(0.1,0.0,0.0,1.0)

Interacts poorly with non-pixel perfect moving objects.

Edit: Just to clarify on the non shaded colour. If you wanted pure green that wouldn’t get shaded you’d put Color(0.01,1.0,0.01,1.0).

Shader code
shader_type canvas_item;
uniform vec4 Red: hint_color;
uniform vec4 Magenta: hint_color;
uniform vec4 Green: hint_color;
uniform vec4 Yellow: hint_color;
uniform vec4 Blue: hint_color;
uniform vec4 Cyan: hint_color;

void fragment(){
	vec4 col = texture(TEXTURE, UV);
	vec4 chosen_col = col;
 	if (col.r == 0.0){
		if (col.b == 0.0){
			if (col.g > 0.0){
				chosen_col.rgb = Green.rgb*col.g;
			}
		}else{
			if(col.g == 0.0){
				chosen_col.rgb = Blue.rgb*col.b;
			}else{
				chosen_col.rgb = Cyan.rgb*((col.g+col.b)/2.0);
			}
		}
	}else{
		if (col.b == 0.0){
			if (col.g == 0.0){
				chosen_col.rgb = Red.rgb*col.r;
			}else{
				chosen_col.rgb = Yellow.rgb*((col.r+col.g)/2.0);
			}
		}else{
			if (col.g == 0.0){
				chosen_col.rgb = Magenta.rgb*((col.r+col.b)/2.0);
			}
		}
	}
    COLOR = chosen_col;
}
Tags
2d, colour, palette, team

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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.
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Filip Novotný
Filip Novotný
8 months ago

Looks very cool, I’m just feared about the performance, because using lots of if statements is highly unrecommended in shaders.

Dubey
Dubey
8 months ago
Reply to  Filip Novotný

It branches up to three times. Using several sqrt is worse than that in most cases.

I’ve never had a problem with hundreds of instances on screen. You’d have to stress test it (as you should do with any shader code) but my question would be why aren’t you using a texture substitution if you want more than a few hundred instances?

William Godwin
William Godwin
8 months ago

Too many branching operators. It is much more efficient to use a constant array of vectors.