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How can I load bufferedImage as opengl texture?

I'm trying to create a texture from a loaded Buffered image like this:

public static long loadTexture(String img) throws IOException{


     File imgPath = new File(img);
     BufferedImage bufferedImage = ImageIO.read(imgPath);


    byte[] pixels = ((DataBufferByte) bufferedImage.getRaster().getDataBuffer()).getData();
    int id = glGenTextures();

    glBindTexture(GL_TEXTURE_2D, id);

    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, bufferedImage.getWidth(), bufferedImage.getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, ByteBuffer.wrap(pixels));

    glGenerateMipmap(GL_TEXTURE_2D);

    return id; 
}

But this code gives me a java sigsegv error. I am using a Java.nio.Bytebuffer because the sun one isn't supported in java 11. So what am I doing wrong? The Image is loaded correctly, with 4bpp:

//last 2 digits are lenght
FF-AD-6F-CB-FF-FF-FF-00-FF-FF-FF-00-FF-FF-FF-00-FF-FF-FF-00-FF-00-00-FF-FF-00-00-FF-FF-FF-FF-00-FF-FF-FF-00-FF-00-00-FF-FF-00-00-FF-FF-FF-FF-00-FF-FF-FF-00-FF-FF-FF-00-FF-FF-FF-00-FF-FF-FF-00-64

Heres the image: enter image description here its pretty small of course but the data is correct.

So why am I getting a sigsegv? the log is pretty useless and long so I can't post it.

And how do I create an opengl texture from a 4bpp byte array?

Solution

  • As suggested in Java Code Examples for org.lwjgl.opengl.GL11.glTexImage2D() (Example 5) you have to copy the data to a ByteBuffer in loops:

    public static long loadTexture(String img) throws IOException{

    File imgPath = new File(img);
    BufferedImage image = ImageIO.read(imgPath);

    int[] pixels = new int[image.getWidth() * image.getHeight()];
    image.getRGB(0, 0, image.getWidth(), image.getHeight(), pixels, 0, image.getWidth());
    ByteBuffer buffer = ByteBuffer.allocateDirect(image.getWidth() * image.getHeight() * 4);

    for(int h = 0; h < image.getHeight(); h++) {
        for(int w = 0; w < image.getWidth(); w++) {
            int pixel = pixels[h * image.getWidth() + w];

            buffer.put((byte) ((pixel >> 16) & 0xFF));
            buffer.put((byte) ((pixel >> 8) & 0xFF));
            buffer.put((byte) (pixel & 0xFF));
            buffer.put((byte) ((pixel >> 24) & 0xFF));
        }
    }

    buffer.flip();

    int id = glGenTextures();
    glBindTexture(GL_TEXTURE_2D, id);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, image.getWidth(), image.getHeight(),
                 0, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
    glGenerateMipmap(GL_TEXTURE_2D);

    return id; 
}

    Note, glPixelStorei(GL_UNPACK_ALIGNMENT, 1) is unnecessary in that case, because the size of a RGBA pixel is 4 bytes, so each row is aligned to 4 bytes and GL_UNPACK_ALIGNMENT by default is 4.

    Furthermore, if you want to use Mipmaps (glGenerateMipmap), then the minifying function (GL_TEXTURE_MIN_FILTER) has to be GL_NEAREST_MIPMAP_NEAREST, GL_LINEAR_MIPMAP_NEAREST, GL_NEAREST_MIPMAP_LINEAR or GL_LINEAR_MIPMAP_LINEAR. (See glTexParameter)