Question

I have fix the problem and following is how I did it,

The binding code in RenderEngine:

public int bindTexture(String location)
{
    BufferedImage texture;
    File il = new File(location);

    if(textureMap.containsKey(location))
    {
        glBindTexture(GL_TEXTURE_2D, textureMap.get(location));
        return textureMap.get(location);
    }

    try 
    {
        texture = ImageIO.read(il); 
    }
    catch(Exception e)
    {
        texture = missingTexture;
    }

    try
    {
        int i = glGenTextures();
        ByteBuffer buffer = BufferUtils.createByteBuffer(texture.getWidth() * texture.getHeight() * 4);
        Decoder.decodePNGFileToBuffer(buffer, texture);
        glBindTexture(GL_TEXTURE_2D, i);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, texture.getWidth(), texture.getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
        textureMap.put(location, i);
        return i;
    }
    catch(Exception e)
    {
        e.printStackTrace();
    }

    return 0;
}

And the PNG decoder method:

public static void decodePNGFileToBuffer(ByteBuffer buffer, BufferedImage image)
{
    int[] pixels = new int[image.getWidth() * image.getHeight()];
    image.getRGB(0, 0, image.getWidth(), image.getHeight(), pixels, 0, image.getWidth());

    for(int y = 0; y < image.getHeight(); y++)
    {
        for(int x = 0; x < image.getWidth(); x++)
        {
            int pixel = pixels[y * image.getWidth() + x];
            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();
}

I hope this helps anybody with the same problem
P.S. textureMap is just a HashMap with String as the key and a Integer as the value

Answer 1

You’ve got the order completely wrong. You need to:

1. Generate a texture name/ID with glGenTextures – store that ID in a variable
2. Bind that ID using glBindTexture
3. any only then you can upload the data with glTexImage

In your drawing code you’re calling the whole texture load, which is inefficient, also you’re recreating a new texture name each time. Use a map to map texture filenames to an ID, and only if no ID has been assigned yet Gen/Bind/TexImage the texture. Otherwise, just Bind it.