NV_system_time

EGL_NV_system_time

Jason Allen, NVIDIA Corporation (jallen 'at' nvidia.com)

TBD

Version 1, July 7, 2011

EGL Extension #31

Requires EGL 1.2

This extension exposes an alternative method of querying the system time
from the driver instead of the operating system. 

Add 64 bit types?

  Yes, EGL doesn't support any 64 bit types so this extension adds int64
  and uint64 types.

EGLint64NV: 64bit signed integer
EGLuint64NV: 64bit unsigned integer

EGLuint64NV eglGetSystemTimeFrequencyNV(void);
EGLuint64NV eglGetSystemTimeNV(void);

None

The command:

    EGLuint64NV eglGetSystemTimeFrequencyNV(void);

returns the frequency of the system timer, in counts per second. The
frequency will not change while the system is running.

The command:

    EGLuint64NV eglGetSystemTimeNV(void);

returns the current value of the system timer. The system time in seconds
can be calculated by dividing the returned value by the frequency returned
by the eglGetSystemTimeFrequencyNV command.

Multiple calls to eglGetSystemTimeNV may return the same values, applications
need to be careful to avoid divide by zero errors when using the interval
calculated from successive eglGetSystemTimeNV calls.

EGLuint64NV frequency = eglGetSystemTimeFrequencyNV();

loop
{
    EGLuint64NV start = eglGetSystemTimeNV() / frequency;

    // draw 

    EGLuint64NV end = eglGetSystemTimeNV() / frequency;

    EGLuint64NV interval = end - start;
    if (interval > 0)
        update_animation(interval);

    eglSwapBuffers(dpy, surface);
}