Function createDiffuseAlphaTexture

lib/loadMtl.js:511–596

(diffuseTexture, alphaTexture, options)

}

function createDiffuseAlphaTexture(diffuseTexture, alphaTexture, options) {
  const packDiffuse = defined(diffuseTexture);
  const packAlpha = defined(alphaTexture);

  if (!packDiffuse) {
    return undefined;
  }

  if (!packAlpha) {
    return diffuseTexture;
  }

  if (diffuseTexture === alphaTexture) {
    return diffuseTexture;
  }

  if (!defined(diffuseTexture.pixels) || !defined(alphaTexture.pixels)) {
    options.logger(
      `Could not get decoded texture data for ${diffuseTexture.path} or ${alphaTexture.path}. The material will be created without an alpha texture.`,
    );
    return diffuseTexture;
  }

  const packedTextures = [diffuseTexture, alphaTexture];
  const dimensions = getMinimumDimensions(packedTextures, options);
  const width = dimensions[0];
  const height = dimensions[1];
  const pixelsLength = width * height;
  const pixels = Buffer.alloc(pixelsLength * 4, 0xff); // Initialize with 4 channels
  const scratchChannel = Buffer.alloc(pixelsLength);

  // Write into the R, G, B channels
  const redChannel = getTextureChannel(
    diffuseTexture,
    0,
    width,
    height,
    scratchChannel,
  );
  writeChannel(pixels, redChannel, 0);
  const greenChannel = getTextureChannel(
    diffuseTexture,
    1,
    width,
    height,
    scratchChannel,
  );
  writeChannel(pixels, greenChannel, 1);
  const blueChannel = getTextureChannel(
    diffuseTexture,
    2,
    width,
    height,
    scratchChannel,
  );
  writeChannel(pixels, blueChannel, 2);

  // First try reading the alpha component from the alpha channel, but if it is a single color read from the red channel instead.