@mesmotronic/three-retropass/dist/utils/createColorPalette.js

RetroPass applies a retro aesthetic to your Three.js project, emulating the visual style of classic 8-bit and 16-bit games

import * as THREE from 'three';
/**
 * Creates a 3D cube quantized colour palette the same or smaller than the
 * specified size, by default padded with greyscale up to the size.
 */
export function createQuantizedColorPalette(size = 0, padded = true) {
    const levels = Math.min(16, Math.floor(Math.pow(size + 1, 1 / 3)));
    const palette = [];
    let divisor = levels - 1;
    for (let r = 0; r < levels; r++) {
        for (let g = 0; g < levels; g++) {
            for (let b = 0; b < levels; b++) {
                palette.push(new THREE.Color(r / divisor, g / divisor, b / divisor));
            }
        }
    }
    if (padded) {
        const cubeSize = palette.length;
        divisor = size - cubeSize - 1;
        while (palette.length < size) {
            const v = (palette.length - cubeSize) / divisor;
            palette.push(new THREE.Color(v, v, v));
        }
    }
    return palette;
}
/**
 * Creates a color palette based on the specified color count
 */
export function createColorPalette(colorCount) {
    let colorPalette = [];
    switch (true) {
        // Find optimised palette closest to the requested color count
        case colorCount > 16: {
            colorPalette = createQuantizedColorPalette(colorCount);
            break;
        }
        // 16 colours - Microsoft Windows Standard VGA Palette
        case colorCount > 8: {
            colorPalette = [
                new THREE.Color(0x000000), // Black
                new THREE.Color(0x0000AA), // Blue
                new THREE.Color(0x00AA00), // Green
                new THREE.Color(0x00AAAA), // Cyan
                new THREE.Color(0xAA0000), // Red
                new THREE.Color(0xAA00AA), // Magenta
                new THREE.Color(0xAA5500), // Brown
                new THREE.Color(0xAAAAAA), // Light Gray
                new THREE.Color(0x555555), // Dark Gray
                new THREE.Color(0x5555FF), // Light Blue
                new THREE.Color(0x55FF55), // Light Green
                new THREE.Color(0x55FFFF), // Light Cyan
                new THREE.Color(0xFF5555), // Light Red
                new THREE.Color(0xFF55FF), // Light Magenta
                new THREE.Color(0xFFFF55), // Yellow
                new THREE.Color(0xFFFFFF), // White
            ];
            break;
        }
        // 8 colours - Similar to ZX Spectrum (without dark shades), BBC Micro, Acorn Electron
        case colorCount > 4: {
            colorPalette = createQuantizedColorPalette(colorCount);
            break;
        }
        // 4 colours - CGA Mode 1 (Palette 0, High Intensity)
        case colorCount > 2: {
            colorPalette = [
                new THREE.Color(0x000000), // Black
                new THREE.Color(0x55FFFF), // Cyan
                new THREE.Color(0xFF55FF), // Magenta
                new THREE.Color(0xFFFFFF), // White
            ];
            break;
        }
        // 2 colours - Monochrome
        case colorCount >= 0: {
            colorPalette = [
                new THREE.Color(0x000000), // Black
                new THREE.Color(0xFFFFFF), // White
            ];
            break;
        }
        default: {
            throw new Error(`Invalid colorCount: ${colorCount}`);
        }
    }
    if (colorPalette.length !== colorCount) {
        console.warn(`${colorCount} colour palette not available, returned ${colorPalette.length}.`);
    }
    return colorPalette;
}