Posted by NickJPGeorge on Oct 08, 2010; 8:37pm
URL: https://forum.jogamp.org/Empty-Begin-End-drawing-things-tp1667610.html

EDIT: I realize how difficult it is to make any sense of the following problem, and I know no one wants to sift through the gory details of my program, so let me simply state:  I have something that's being drawn occasionally (maybe 1 in 20 times) in my program, when I have an empty glBegin(GL2.GL_QUADS);gl.glEnd();, that is not being drawn if I comment that out.  Why would that happen?


Longer version:

Ok, this is simply the most perplexing bug I've ever had with JoGL.  It took me many many hours just to characterize the bug this far.  The simplest way I can describe it is the following:

Something seems to be getting stuck in some kind of buffer.  My program draws a lot of a specific object (a box made with quads).  Originally I used a gl list for this, but for the sake of debugging, I made it make explicit calls every time.  I also have a sprite effect.  Sometimes when I draw the sprite effect, it gets covered up with a box that shouldn't be there.  I found that if I replaced the ENTIRE sprite drawing with

                gl.glBegin(GL2.GL_QUADS);
                gl.glEnd();

the box would somehow still be drawn.  If I comment out these last two lines, the box is not drawn.  Therefore, somehow, just having a begin/end with no code in between is causing an earlier displayed series of quad calls (the box) to be recalled.  What on earth could be causing this?!

Thanks for any help,
Nick