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Re: Weird figures with OpenGL 3.2 and Intel HD3000 Ingemar Ragnemalm Thu Feb 02 06:07:16 2012


400000 triangles is a lot, but when 15000 takes the same time, there is another bottleneck somewhere. What happens for very small models? Still 10 ms? How about drawing several? Maybe the overhead is somewhere else?

I can try the same program on a 9400 if you like, to see if it is the same for other GPUs.


/Ingemar


justin meiners wrote:
You are rendering quite a bit of geometry, do you have another
benchmark to test it against to see how your Mac performs with that?
My experience with intel graphics is not great and It wouldn't
surprise me if you are maxing it out.

Sent from my iPod

On Jan 17, 2012, at 7:15 AM, Vincent Habchi <[EMAIL PROTECTED]> wrote:

Hi there,

I’m getting what I consider to be far too big drawing time with a small app 
using GL 3.2 Core Profile I’m currently programming. I run it on the latest 
MacMini, with no discrete GPU (so relying on Intel HD3000). More specifically, 
the drawing of a textured sphere takes around 10 µs, a figure almost 
independent of the number of vertices:

9079.92 µs  glDrawElements(GL_TRIANGLES, 15552, GL_UNSIGNED_SHORT, 0x00000000);
10583.03 µs glDrawElements(GL_TRIANGLES, 97200, GL_UNSIGNED_SHORT, 0x00000000);
8720.80 µs glDrawElements(GL_TRIANGLES, 388800, GL_UNSIGNED_SHORT, 0x00000000);

Neither the vertex nor the fragment shader are trivial, but I have tried to 
optimize both: I moved lightning from fragment to vertex level, and got rid of 
both DOT3 lightning and shadow mapping. To stay concise, the vertex level 
computes a basic Phong lightning, and fragment level fetches one or two 
textures and applies some blending (multi-texturing) if necessary.

Size of window does not seem to alter the time spent in glDrawElements. I have 
tried to modify various texture parameters (GL_UNPACK_ALIGNMENT), the kind of 
filter applied for mip-maping, and so on. No change.

These figures above correspond to a single sphere, I have two to draw and the 
GL cannot keep up with the 60 Hz display link (I get 50 fps at maximum).

Do anybody have an idea of why it does take so long?

Thanks a lot,
Vincent _______________________________________________
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