Advanced Palette (Godot 4)
Advanced Palette, Godot 4 version.
Enables the use of swappable 256-color palettes and partial or full sprite color cycling, with a toggle for blending between each cycle step.
Requires recoloring the sprite. In return, you can supply palettes as PNG files of any width and height and with more or fewer colors than the sprite was designed for, and they will be handled automatically.
An alternative version that allows for multiple palettes to be defined in a single PNG file is available from Github.
A tutorial on how to use Advanced Palette is available at the below “See more” link.
Shader code
// Godot 4 Advanced Palette Shader
shader_type canvas_item;
#pragma disable_preprocessor
uniform bool disableProcessing;
uniform vec4 modulate: source_color = vec4(1.0);
group_uniforms palette;
uniform sampler2D palette: filter_nearest;
group_uniforms cycling;
uniform int cycleMode: hint_range(0, 2, 1);
uniform float cycleRate: hint_range(-120, 120, 1);
uniform float cycleOffset: hint_range(0, 256, 0.1);
uniform bool colorBlending;
vec4 applyPalette(vec4 sprTex)
{ // Palette data
ivec2 palSize = textureSize(palette, 0);
int palCount = palSize.x * palSize.y;
// Color channel data
float idxPalette = floor(sprTex.r * 256.00); // Color index
float idxCycEnds = floor(sprTex.g * 256.00); // Color cycle end index
float idxCycLeng = floor(sprTex.b * 256.00); // Color cycle length
// Cycling
float idxCycle = cycleOffset + TIME * cycleRate; // Cycle frame
float idxCycNext = idxPalette;
// Ignore index #0
if (idxPalette > 0.0)
{
switch (cycleMode)
{
case 1: // Localized color cycling
if (idxCycEnds * idxCycLeng > 0.0)
{
idxPalette = floor(idxPalette + mod(idxCycle, idxCycLeng));
idxCycNext = idxPalette + 1.0;
// Wrap indices around if they exceed end of cycle
if (idxPalette > idxCycEnds)
idxPalette -= idxCycLeng;
if (idxCycNext > idxCycEnds)
idxCycNext -= idxCycLeng;
}
break;
case 2: // Palette-wide color cycling
idxPalette = floor(idxPalette + idxCycle);
idxCycNext = idxPalette + 1.0;
break;
}
// Wrap indices back within palette bounds, skipping index 0
idxPalette = mod(idxPalette - 1.0, float(palCount - 1)) + 1.0;
idxCycNext = mod(idxCycNext - 1.0, float(palCount - 1)) + 1.0;
}
// Palette sampler UV
float yxUV = idxPalette / float(palSize.x);
// Sample palette from center of pixel (maximum result accuracy)
float xUV = fract(yxUV) + (0.5 / float(palSize.x));
float yUV = floor(yxUV) / float(palSize.y) + (0.5 / float(palSize.y));
vec2 palUV = vec2(xUV, yUV);
if (!colorBlending)
{
// Unblended result
return texture(palette, palUV);
}
else
{
// Next cycle step sampler UV
float nyxUV = idxCycNext / float(palSize.x);
// Center next index sampler
float nxUV = fract(nyxUV) + (0.5 / float(palSize.x));
float nyUV = floor(nyxUV) / float(palSize.y) + (0.5 / float(palSize.y));
vec2 nxtUV = vec2(nxUV, nyUV);
// Blend result
vec4 pixel = texture(palette, palUV);
vec4 next = texture(palette, nxtUV);
return mix(pixel, next, fract(idxCycle));
}
}
void fragment()
{
if (!disableProcessing)
{
COLOR = applyPalette(texture(TEXTURE, UV)) * modulate;
}
}
