Re: info-performer Oct 08 1999
Jean-Francois Panisset (panisset++at++discreet.com)
Sat, 09 Oct 1999 16:17:05 -0400
>
> From: Sylvain Mayer <mayer++at++CAE.CA>
> Date: Fri, 08 Oct 1999 16:53:11 -0400
> Subject: image processing on an O2
>
>Good morning,
>
>is there any particularities using convolution stuff on O2?
>
>I have some code that runs fine on an Indigo2/Impact but runs very slowly on m
>y
>O2. Here are the portions of code I suspect is causing slowdown (which is tak
>en
>from the draw function of a pfChannel derived class):
>
> glSeparableFilter2DEXT( GL_SEPARABLE_2D_EXT,
> GL_LUMINANCE,
> 3, 3, GL_LUMINANCE, GL_FLOAT,
> kern, kern );
>
> // apply scaling factor
> glPixelTransferf(GL_RED_SCALE,gain);
> glPixelTransferf(GL_GREEN_SCALE,gain);
> glPixelTransferf(GL_BLUE_SCALE,gain);
>
> // apply bias factor
> glPixelTransferf(GL_RED_BIAS,level);
> glPixelTransferf(GL_GREEN_BIAS,level);
> glPixelTransferf(GL_BLUE_BIAS,level);
>
> // set color table
> glColorTableSGI(GL_COLOR_TABLE_SGI, GL_RGBA8_EXT, colorTableSize,
> GL_LUMINANCE, GL_UNSIGNED_BYTE, colorTable);
>
> // Perform color table lookup followed by convolution.
> glEnable(GL_COLOR_TABLE_SGI);
> glEnable(GL_SEPARABLE_2D_EXT);
> glCopyPixels(0,0,sizeX,sizeY,GL_COLOR);
>
>
>Is it normal that it is slow on an O2 ??
>
>My desktop is configured to be 32+32 bitplanes and I tried using the following
>pixel format: 0x3a, 0x3b but any of these would give me good performance. I'
>m
>using Performer 2.2.2 and IRIX 6.3.
>
The problem is most likely not with convolutions, but with the LUTs
you are enabling with glColorTableSGI(): LUTs are not hardware-accelerate
on the O2 as far as I can tell, and force you into the very slow software
path. Try removing the color table and enabling only the convolution,
it should probably be faster.
JF
Jean-Francois Panisset panisset++at++discreet.com
Software Engineer
Discreet Logic
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on Sat Oct 09 1999 - 13:17:12 PDT