Slick Forums

Hey there,

I noticed something weird when using Image.getColor.
I have an OpenGL displaylist containing my terrain. When generating the displaylist I get the color of an Image at every point of the heightmap, using getColor(xx,yy) in my for-loop. However, I've noticed that after I did that, my terrain suddenly got the heightmap texture. So I did some debugging and when I removed the getColor line for checking my height, the texture didn't change. I've looked through the source code but can't find anything that causes this.

Anyone got an idea why this happens/how this can be fixed?

Yes, it binds a texture.

The first time it's called, it copies pixels from the backing texture via glGetTexImage. The data is cached until next time you call flushPixelData() or whenever you change the image through getGraphcis().flush() -- that will set the data to null, forcing it to copy next time you try to call getColor.

Calling getColor beforehand and then being careful not to use getGraphics() will ensure that it only binds once.

For maximum performance, load the image into a byte buffer using Slick's LoadableImageData utility, and then read the pixel data directly. Using Image.getColor for your height map means an OpenGL texture has to be constructed for something that you'll never need to show on-screen and the data needs to be copied into an array using glGetTexImage.