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Jitendra Tiwari's questions

Martin Hope
Jitendra Tiwari
Asked: 2024-08-08 21:15:00 +0800 CST
  • 6

我正在使用 PNGDecoder 解码高度图 png。然而，当我打印控制台中返回的值时，我发现一些 rgb 值返回为负数

-128, -128, -128, -1
-128, -128, -128, -1
-128, -128, -128, -1
-124, -124, -124, -1
-119, -119, -119, -1
-118, -118, -118, -1

我用来解码然后读取的代码如下

public static ByteBuffer decodeImage(String path) throws IOException {
        InputStream stream = new FileInputStream(path);
        PNGDecoder decoder = new PNGDecoder(stream);
        ByteBuffer decodedImageData = ByteBuffer.allocateDirect(4 * decoder.getWidth() * decoder.getHeight());
        decoder.decodeFlipped(decodedImageData, decoder.getWidth() * 4, PNGDecoder.Format.RGBA);
        decodedImageData.flip();
        return decodedImageData;
    }

private void applyHeightMap (String heightMapPath) throws IOException {
        float vertices[] = plane.getVertices();
        ByteBuffer buffer = Texture.decodeImage(heightMapPath);
        for (int i = 0; i < 2624 * 1756; i++) {
            byte r = buffer.get();
            byte g = buffer.get();
            byte b = buffer.get();
            byte a = buffer.get();
            if(r < 0 || b < 0 || g < 0) {
                System.out.println(r + ", " + g + ", " + b+", "+a);
            }
        }
    }

不确定为什么负值很少，以及为什么 alpha 通道读为 -1

我使用的图像是https://learnopengl.com/img/guest/2021/tessellation/height_map/iceland_heightmap.png

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