#5 Huge CPU usage?

open
nobody
None
5
2008-07-24
2008-07-24
James Gregory
No

Steps to reproduce:
1. Run "top" in a terminal
2. Run the provided FTGLDemo in another terminal

On my AMD 3400+ with Geforce 6800 this uses about 87% CPU.

Strangely, if I then click with the mouse on the demo text to slightly adjust the viewing angle, CPU usage then drops to pretty much zero.

Discussion

  • If you click-and-drag the text and release the mouse while dragging, the text continues 'spinning'. The screen updates many times per second, appearing as an animation. This will use more CPU usage.

    When the application starts, the screen is drawing itself over-and-over the same way it would if you had done the above drag-and-release action, but there is no delta in any of the axis so the text does not appear to move. This is why if you "click", causing the animation to stop, the cpu usage drops.

    seems like the bug is really that there is no delta on any axis so the screen shouldn't have to refresh over and over.