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RE: What's the poop on point sprites?



Title: What's the poop on point sprites?
On PowerPC machines running Tiger, OpenGL didn't receive any updates since 10.4.3 so there were a lot of long-standing bugs that didn't get addressed until Leopard. If you can't require Leopard, you are basically on your own to work around the issues. Intel was a little more lucky and got several updates during 10.4's lifespan, though whether it will see any future updates is an open quesion.
 
You should probably be more specific about which configurations work and which do not... that might help narrow down the issues more specifically. OS version, Intel-or-PowerPC and GPU type are the most important variables.

From: mac-opengl-bounces+jstiles=email@hidden on behalf of Richard S. Wright Jr.
Sent: Tue 10/30/2007 10:09 AM
To: OpenGL Mailing List List
Subject: What's the poop on point sprites?


I'm using point sprites and a custom shader to render a star field in 
an astronomy program. Switching to this method makes my star fields 
almost "free", so it's a very desirable optimization (they are 
rendered via a VBO). I have four test machines, and depending on how I 
move the shells around (a metaphor for you non-american readers) I get 
a variety of results:

Newer machines running Tiger or Leopard... wow, that's fast and pretty.

Older machines, depending on the order of operations, or changes to 
the shader... locks up machine completely with a test shader (OS X 
10.4.11), or stars are always green (same machine), or points do not 
obey GL_VERTEX_PROGRAM_POINT_SIZE.
I've never seen a single OpenGL feature behave so many different ways 
on different machines/configurations. Point sprites really don't seem 
to me to be _that_ hard to implement...

A search of the archives reveals that all these problems have been 
reported before, but no one from Apple seems to have any response (or 
if so, I have missed them). Older ATI hardware with 9600 based 
chipsets... is this EVER going to be fixed? I'm running the newest 
10.4.11 PPC build and my whole machine just freak'n hangs. I would be 
happy to at least hear "this is a hardware limitation and we just 
can't fix it". At least that would show up in the archives and all us 
point sprite fan boys could give up our false hopes ;-)

Richard


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References: 
 >What's the poop on point sprites? (From: "Richard S. Wright Jr." <email@hidden>)



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