没有光滑的OpenGL纹理

Question

I searched for Texture Implementations without the Slick Utils library. I found 2 ways, to do this:

The first, saves the pixels with strange byteshifting in a byte buffer:

int loadTexture(){
        try{
            BufferedImage img = ImageIO.read(getClass().getClassLoader().getResourceAsStream("background.png"));
            int pixels[] = new int[img.getWidth() * img.getHeight()];
            img.getRGB(0, 0, img.getWidth(), img.getHeight(), pixels, 0, img.getWidth());
            ByteBuffer buffer = BufferUtils.createByteBuffer(img.getWidth() * img.getHeight() * 3);
            for(int x = 0; x < img.getWidth(); x++){
                for(int y = 0; y < img.getHeight(); y++){
                    int pixel = pixels[y * img.getWidth() + x];
                    buffer.put((byte) ((pixel >> 16) & 0xFF));
                    buffer.put((byte) ((pixel >> 8) & 0xFF));
                    buffer.put((byte) (pixel & 0xFF));
                }
            }
            buffer.flip();
            int textureId = glGenTextures();
            glBindTexture(GL_TEXTURE_2D, textureId);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL12.GL_CLAMP_TO_EDGE);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL12.GL_CLAMP_TO_EDGE);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, img.getWidth(), img.getHeight(), 0, GL_RGB, GL_UNSIGNED_BYTE, buffer);
            return textureId;
        }
        catch(Exception e){
            e.printStackTrace();
            return 0;
        }
    }

This returns a texture id as well, and i haven't any idea how tu use this id.

The second way doesnt do any byteshifting, and uses a IntBuffer: Also, it is a ready class to save different textures with names and so on. The Code of these:

ublic class TextureIO {

    private final IntBuffer texture;
    private final int       width;
    private final int       height;

    private int             id;


    public TextureIO(final InputStream inputStream) throws IOException {

        BufferedImage image = ImageIO.read(inputStream);

        width = image.getWidth();
        height = image.getHeight();

        final AffineTransform tx = AffineTransform.getScaleInstance(1, -1);
        tx.translate(0, -height);

        final AffineTransformOp op = new AffineTransformOp(tx, AffineTransformOp.TYPE_NEAREST_NEIGHBOR);
        image = op.filter(image, null);

        final int[] pixels = image.getRGB(0, 0, width, height, null, 0, width);
        texture = BufferUtils.createIntBuffer(pixels.length);
        texture.put(pixels);
        texture.rewind();

    }


    public void init() {

        GL11.glEnable(GL11.GL_TEXTURE_2D);

        final IntBuffer buffer = BufferUtils.createIntBuffer(1);
        GL11.glGenTextures(buffer);
        id = buffer.get(0);

        GL11.glBindTexture(GL11.GL_TEXTURE_2D, id);
        GL11.glTexParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_MAG_FILTER, GL11.GL_LINEAR);
        GL11.glTexParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_MIN_FILTER, GL11.GL_LINEAR);

        GL11.glTexImage2D(GL11.GL_TEXTURE_2D, 0, GL11.GL_RGBA8, width, height, 0, GL12.GL_BGRA, GL12.GL_UNSIGNED_INT_8_8_8_8_REV, texture);

        GL11.glBindTexture(GL11.GL_TEXTURE_2D, 0);

    }


    public void bind() {

        GL11.glBindTexture(GL11.GL_TEXTURE_2D, id);

    }


    public void unbind() {

        GL11.glBindTexture(GL11.GL_TEXTURE_2D, 0);

    }


}

Im really new to lwjgl development, and want to know which version is better. Cause im a friend of implementing such things by myself, i want the lwjgl.jar to be the own library im using.

I read on different sites, the buffer.flip() method would be necassary. but why? And why the second version doesnt do this? Also, i want to understand the difference between this two implementations, what happens in the first and what in the second?

Thank you!

Answer 1

Both of those are pretty bad implementations IMO. I would recommend watching this video for a more standard approach. Although you would have to also use the PNGDecoder.jar library it is like an extension to the lwjgl library.