glReadPixels not available

OpenGL Development JOGL Development
#1

Hi,

I am trying to capture the OpenGL screenbuffer in an image. Having ascertained that JOGL has no direct support for creating an offscreen buffer, rendering into it, and saving its contents, I’ve moved onto just resizing my window and using glReadPixels to try and capture the data.

However, glReadPixels does not change the contents of its array - so the image never gets there. This is not the issue I wish to raise right now. I have set this up as an issue (#84).

The problem I have right now is that I call isFunctionAvailable(“glReadPixels”) or isExtensionAvailable(“glReadPixels”) and they both return false!

Why is glReadPixels not showing up? Has anyone else had this problem? Does anyone actually read the issues on the web page and do anything about them?

Pete

#2

Hmm. I’m really not enjoying my experience with JOGL so far.

glIsFunctionAvailable(“glBegin”) returns false also. What is the point of this function? Isn’t it supposed to return true to indicate the availability of core opengl functions? glBegin clearly is available because I’m successfully using it.

So, who’s going to be first to help me out with my issue 84?

Pete

#3

Strange. I just tested the function isFunctionAvailable(String) and it threw an exception for a couple of common core GL functions. Strange because the functions work fine for me.

I would recommend not using this function to test for core functionality. I didn’t even know it existed. I have not had any problems using the core GL functions.

Sean

#4

Also, for what it’s worth, I haven’t had any problems using glReadPixels to capture the framebuffer.

Sean

#5

Hi,
I think that “glIsFunctionAvailable” was meant to be used to seek if extensions were available… So what Sylvie says about core functions seems right to me.