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View Full Version : glDrawPixels on Matrox Millenium G450.



itzike
06-21-2004, 07:59 AM
I made a simple function with the following code:

glPushAttrib(GL_COLOR_BUFFER_BIT);
glDisable(GL_BLEND);
glDisable(GL_LINE_STIPPLE);
glPixelStorei(GL_UNPACK_ALIGNMENT,4);
glRasterPos2i(10, 10);
glDrawPixels( (GLsizei)320, (GLsizei)240,GL_RGBA, GL_UNSIGNED_BYTE, rgbData);
glPopAttrib();

It runs on Windows XP Pentium IV 1.8GHz.
With Matrox Millenium G450 graphic card.
The dual screen is off.

I take about 50 milliseconds to run this code with hardware acceleration, and about 7 milliseconds without hardware acceleration or Microsoft default driver which both of these scores are bad results.

Any idea why?
How can I improve it to a reasonable score?

Thanks.

Relic
06-21-2004, 08:17 AM
If it should be a pure color 2D drawing you need to switch off more:
DEPTH_TEST(!)
LIGHTING
LOGIC_OP
POLYGON_STIPPLE
DITHER

Try different formats like GL_BGRA_EXT.
If that all doesn't help, maybe the Matrix (edit: Hehe, bon mot typo, I meant Matrox) implementation is just not HW accelerated.

Try downloading as Texture and drawing a textured quad. (Switch off everything you don't need too here.)

itzike
06-21-2004, 11:16 PM
I tried to disable every flag, it doesn't improve anything.
Even though, isn't it too big diffrence between hardware and software? 50ms(hardware) against 7ms(software). Shouldn't it be contrary?

Any idea?

Relic
06-22-2004, 02:08 AM
No, that's explainable. The software implementation uses drawing buffers in system memory. The addressing of video memory can be much slower.
G450 is not very new nor highend, and Matrox OpenGL support is not famous.
If glDrawPixels is still too slow try the other hints. This topic has been dicussed often before, search the forum.