On 28-Apr-06, at 5:24 PM, Mike Woodworth wrote:
hey all,
i'm looking into speeding up an app i'm currently workign on by
using opengl to do the screen drawing. i found asher's opengl
declare library, and i started trying to shoe horn some of the
examples i've found into his example project... but they don't
work, and i'm not sure where to look. the problem is, the code
compiles fine, but nothing is displayed. for someone with so
little experience, this makes for tough debugging. are there any
tools out there to help me try to diagnose the problem? or does
opengl fail silently when trying to load something improperly?
You should call glGetError frequently in debug builds to get an idea
of where (or if) stuff is failing. Set up a method that calls
glGetError in a loop until it returns GL_NO_ERROR, and log any errors
it finds (System.DebugLog will do in a pinch). I call a method like
this at the end of every single method that declares into OpenGL,
passing the current method name so I can easily go in and narrow
things down further when needed. Wrap these calls in "#if DebugBuild"
conditionals though, 'cause you don't this overhead for release builds.
You should also call aglGetError during the context/drawable setup
(or whatever's appropriate for the windowing API you're using) but
these errors are usually easier to spot - e.g. the function calls
themselves will fail outright rather than posting an error and
continuing as gl* functions might.
Once you rule out actual errors you'll have to do some tougher
debugging. An empty display could simply mean your projection isn't
set up right, or your geometry is outside the frustum, or facing the
wrong way, etc.
Frank.
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