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Member Since 12 Feb 2011
Offline Last Active Mar 05 2015 01:15 AM

Topics I've Started

Illegal Instruction, possible causes?

11 October 2013 - 08:50 AM

I am getting an Illegal Instruction exception for OpenGL, and I'm wondering what are common causes of this are and how I should go about tracking them down.


  • It only happens on my desktop, but code works fine when I develop on my laptop.  Games and other graphics accelerated applications work fine on the box.
  • I am 99.9% sure a context is current.  I use GLEW in multi-threaded mode, and the context wrapper class sets a thread local GLEWContext to NULL when not current, so OpenGL API functions would not de-reference otherwise.
  • This happens on a call to glClearColor().  This is the first API call I make, but if I put it after my glEnable()/glDisable() initialization, it still fails on glClearColor()
  • I am using a version 4.2 context in compatibility mode.


Thank you for any assistance.

Shading graphs and how they map to implementation in a game engine.

25 July 2013 - 08:02 PM

I have seen that many rendering packages expose shading graphs to artist. I hope I am using the term right, but I am referring to the graphs that typically have a shader as a node, with inputs and outputs of the shader that can be chained to create a final effect.

How are these integrated into a game engine in practice? How do they map to implement ion of the actual shaders compiled and run? It seems like these could get complex very quickly, with either the number of shaders being compiled to support all of the permutations artists might create going through the roof, or a lot of CPU/GPU ping-pong'ing and synching waiting for the output of one stage of the chain being ready for the next stage.

Thanks for any insight.