Sprite3D Indexed Color Palette Swapping Shader

texture_albedo is the image texture you wish to change the palette of.

num_colors is the length of your palette. (it should be 1px in height)

precision is the amount of how accurate it should be, preferable 0.01.

palette_in is the image of the colormap palette.

palette_out is the image of the palette you wish to change the colors to.

Made this because the one’s here didnt work properly for sprite3D.

Have fun ^^! Credit to DETOX and lenscas on discord for helping me figure this out.

Shader code

shader_type spatial;
render_mode blend_mix,depth_draw_alpha_prepass,cull_disabled,unshaded,specular_disabled;
uniform sampler2D texture_albedo : hint_albedo;

uniform int num_colors : hint_range(1, 100, 1) = 1;
uniform float precision : hint_range(0.0, 1.0, 0.01) = 0.1;

uniform sampler2D palette_in : hint_albedo;
uniform sampler2D palette_out : hint_albedo;

vec4 swap_color(vec4 color) {
    float inc = 1.0 / float(num_colors); 
    for (float i = 0.0; i < 1.0; i += inc) {
        vec2 uv = vec2(i, 1.0);
        vec4 color_in = texture(palette_in, uv);
        if (distance(color, color_in) <= precision) {
            return texture(palette_out, uv);
        }
    }
    //return color;
}

void fragment() {
	vec4 albedo_tex = texture(texture_albedo,UV);
	ALBEDO = albedo_tex.rgb;
	ALBEDO = swap_color(albedo_tex).rgb;
	ALPHA = albedo_tex.a;
}

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