pyopengl-users

RE: [Pyopengl-users] patch to trackball.py

[Tarn W. B. <twb...@ma...>]

| 1. trackball.py
|
| I have been playing around with trackballing under C, and I find that
| the trackball.py is horribly broken. It makes me wonder whether it was
| included there by accident. After spending quite a bit of time looking
| at it, I found that there were a fair number of bugs in it, which I have
| fixed up.

No, quaternion was a late addition and I obviously didn't look at trackball
close enough.

I applied some of your changes, but not all.  One thing that worries me is
the line

phi = 2.0 * math.asin(t)

in your source.  This is not in any CVS version.  Which
distribution/platform did you install?

In the future please submit patches via the Patch Tracker at the sourceforge
page.  Also you can always check the current status of code to see if a bug
has already been fixed using the CVS browser.

| 2. Vertex Arrays in PyOpenGL 2.0.44
|
| Are the working ? I just get seg faults everytime I try glDrawElement()
| and others ? Maybe it's just me :)

Yep.  Look at the documentation.  The array functions have slightly
difference prototypes that the spec so this might be the cause.

thanks,
Tarn Weisner Burton

RE: [Pyopengl-users] patch to trackball.py

[Tarn W. B. <twb...@ma...>]

| I've got OpenGLContext installed, maybe I'll have a look at those. The
| demos in the OpenGL directory don't use vertex arrays at all (as far as
| I grepped).

da/dots.py uses glVertexPointerd

Tarn

RE: [Pyopengl-users] patch to trackball.py

[Alastair (L. T. <liq...@op...>]

Hi Tarn,

On 05 Sep 2001 10:44:17 -0500, Tarn Weisner Burton wrote:
> I applied some of your changes, but not all.  One thing that worries me is
> the line
> 
> phi = 2.0 * math.asin(t)

Hehe .. It must have been the comment I wrote below that threw you :)

Actually, I was debugging something and I forgot to remove it. That was
basically from the SGI code that implemented the trackball. The original
trackball.py was right (at least to my little trig knowledge). You can
ignore that line. So the bit should go :

t = max(min(t, 1.0), -1.0)
			
scale = 1.0/math.sqrt(a[0]**2 + a[1]**2 + a[2]**2)
q = [math.sqrt(1.0-t**2)] + map(lambda x, y: x*y, a, [t*scale]*3) 

> In the future please submit patches via the Patch Tracker at the sourceforge
> page.  Also you can always check the current status of code to see if a bug
> has already been fixed using the CVS browser.

Yeah, thanks for the suggestion. I will check the CVS code next time. In
fact I only had a look at the trackball.py code today and was in a rush
to get it working.

> Yep.  Look at the documentation.  The array functions have slightly
> difference prototypes that the spec so this might be the cause.

Thanks for the pointer. I'll take a look at the documentation again.

Cheers,

Alastair.

> 
> thanks,
> Tarn Weisner Burton
> 
> 
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> Pyopengl-users mailing list
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