Re: [PyOpenGL-Users] Fastest way to draw lots of points

[Ian M. <geo...@gm...>]

On Fri, Oct 19, 2012 at 12:37 PM, Henry Gomersall <he...@ca...> wrote:

> On Fri, 2012-10-19 at 14:29 -0400, Ryan Hope wrote:
> > Thanks for the ideas guys. I am a complete OpenGL noob, just started
> > using it last week so things like VBOs and shaders are a little over
> > my head at the moment. I start looking into these things though.
> >
> They're the modern way to do things. To the point that it's probably not
> much worth learning anything else.
>
> Henry

Just because they won't be supported in hardware in 10 years doesn't mean
they're inherently a bad thing. Derakon is right; immediate-mode OpenGL is
easy to use. No, high-end, forward-thinking applications don't use it (as
much), but that doesn't mean it's a worthless technology. Plus, it sounds
like the OP already knows how to use them (and they aren't hard to learn
anyway). They may even have lower overhead than VBOs, because they don't
require expensive buffer glBind(...).

It occurs to me that you could probably rig up a procedural texture
> that would simulate a starfield for you. Then you could just use a set
> of textured quads to do your parallax scrolling starfield. I'm not an
> OpenGL expert though; would anyone more experienced have a sense of
> how this would compare speedwise to the VBO approach? The advantages
> to a procedural texture would be that there'd be no repetition to the
> field, and that of course you'd never have to send more data over to
> the card, except for the parameters to the shader used to generate the
> texture.
>
I would suspect that this would be much slower: any such implementation
would probably be implemented as a fragment program (or at best, and OpenCL
kernel). As such, unless you were very *very* careful, it would be linear
with the number of pixels on the screen, and opposed to linear in the
number of stars. Randomly generating the stars on the CPU into a mapped VBO
implementing a circular buffer would probably accomplish much the same
thing, but faster.

Ian