@ultrapowa/sc-tools/lib/interlacing.mjs

A tool to unpack, repack, edit and play 2d animations from Supercell games

export const deinterlace = (pixels, width, height) => {
  const result = new Array(height * width);
  let pixelIndex = 0;
  for (let currentHeight = 0; currentHeight < height; currentHeight += 32) {
    const subBlockHeight = Math.min(currentHeight + 32, height) - currentHeight;
    for (let i = 0; i < width; i += 64) {
      const subBlockWidth = Math.min(width - i, 64);
      let remaining = subBlockWidth;
      let blockIndex = 0;
      for (let j = i; j < i + subBlockWidth; j += 32) {
        const step = Math.min(remaining, 32);
        remaining -= step;
        let arrayIndex = j + currentHeight * width;
        for (let k = 0; k < subBlockHeight; k += 1) {
          for (let l = 0; l < step; l += 1) {
            result[arrayIndex + l] = pixels[pixelIndex + blockIndex + l];
          }
          arrayIndex += width;
          blockIndex += step;
        }
      }
      pixelIndex += subBlockWidth * subBlockHeight;
    }
  }
  return result;
};

export const interlace = (pixels, width, height) => {
  const result = new Array(height * width);
  let pixelIndex = 0;
  for (let currentHeight = 0; currentHeight < height; currentHeight += 32) {
    const subBlockHeight = Math.min(currentHeight + 32, height) - currentHeight;
    for (let i = 0; i < width; i += 64) {
      const subBlockWidth = Math.min(width - i, 64);
      let remaining = subBlockWidth;
      let blockIndex = 0;
      for (let j = i; j < i + subBlockWidth; j += 32) {
        const step = Math.min(remaining, 32);
        remaining -= step;
        let arrayIndex = j + currentHeight * width;
        for (let k = 0; k < subBlockHeight; k += 1) {
          for (let l = 0; l < step; l += 1) {
            result[pixelIndex + blockIndex + l] = pixels[arrayIndex + l];
          }
          arrayIndex += width;
          blockIndex += step;
        }
      }
      pixelIndex += subBlockWidth * subBlockHeight;
    }
  }
  return result;
};

export default { interlace, deinterlace };