试图解压缩 BC1 纹理压缩的加扰块

Question

我一直在尝试在 Java 中实现 BC1 (DXT1) 解压缩算法。一切似乎都非常精确，但我运行遇到了一些围绕 t运行sparent 块的问题。我一直试图解决它几个小时但没有成功。

简而言之，解压所有块后，除了 t运行sparent 周围的块外，一切看起来都很好。在开发过程中，我一直在检查用 C++ 编写的 DirectXTex (texconv) 的结果。

这是我与 DirectXTex 对比的结果：

这是我使用的代码：

BufferedImage decompress(byte[] buffer, int width, int height)

和实施：

  BufferedImage result = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
  int[] scanline = new int[4 * width]; //stores 4 horizontal lines (width/4 blocks)

  RGBA[] blockPalette = new RGBA[4]; //stores RGBA values of current block

  int bufferOffset = 0;

  for (int row = 0; row < height / 4; row++) {
        for (int col = 0; col < width / 4; col++) {

            short rgb0 = Short.reverseBytes(Bytes.getShort(buffer, bufferOffset));
            short rgb1 = Short.reverseBytes(Bytes.getShort(buffer, bufferOffset + 2));
            int bitmap = Integer.reverseBytes(Bytes.getInt(buffer, bufferOffset + 4));
            bufferOffset += 8;

            blockPalette[0] = R5G6B5.decode(rgb0);
            blockPalette[1] = R5G6B5.decode(rgb1);

            if(rgb0 <= rgb1) {
                int c2r = (blockPalette[0].getRed() + blockPalette[1].getRed()) / 2;
                int c2g = (blockPalette[0].getGreen() + blockPalette[1].getGreen()) / 2;
                int c2b = (blockPalette[0].getBlue() + blockPalette[1].getBlue()) / 2;

                 blockPalette[2] = new RGBA(c2r, c2g, c2b, 255);
                 blockPalette[3] = new RGBA(0, 0, 0, 0);

            } else {
                int c2r = (2 * blockPalette[0].getRed() + blockPalette[1].getRed()) / 3;
                int c2g = (2 * blockPalette[0].getGreen() + blockPalette[1].getGreen()) / 3;
                int c2b = (2 * blockPalette[0].getBlue() + blockPalette[1].getBlue()) / 3;

                int c3r = (blockPalette[0].getRed() + 2 * blockPalette[1].getRed()) / 3;
                int c3g = (blockPalette[0].getGreen() + 2 * blockPalette[1].getGreen()) / 3;
                int c3b = (blockPalette[0].getBlue() + 2 * blockPalette[1].getBlue()) / 3;


                blockPalette[2] = new RGBA(c2r, c2g, c2b, 255);
                blockPalette[3] = new RGBA(c3r, c3g, c3b, 255);

            }

            for (int i = 0; i < 16; i++, bitmap >>= 2) {
                int pi = (i / 4) * width + (col * 4 + i % 4);
                int index = bitmap & 3;
                scanline[pi] = A8R8G8B8.encode(blockPalette[index]);
           }
        }
        //copy scanline to buffered image
        result.setRGB(0, row * 4, width, 4, scanline, 0, width);
  }
  return result;

有谁知道问题出在哪里？我一直在按照规格说明执行完全相同的步骤：Block Compression (Direct3D 10)

Answer 1

难道blockPalette[2].set(c2r, c2g, c2b);应该是blockPalette[2].set(c2r, c2g, c2b, 255);？（在两个位置）

Answer 2

对于那些感兴趣的人，我发现问题在于比较短值。

我刚刚改变了：

if(rgb0 <= rgb1) {

要么

if(Short.compareUnsigned(rgb0, rgb1) <= 0) {

或

if((rgb0 & 0xffff) <= (rgb1 & 0xffff)) {

这确保颜色值作为无符号短裤（正整数）进行比较。

试图解压缩 BC1 纹理压缩的加扰块

scrambled block trying to decompress BC1 texture compression

java

compression

directx

textures

rgba