On Dec 26, 2004, at 10:32 PM, Christopher Niederauer wrote:
I am wondering how I could load an array (or even more than 1) of
vertices (and related colors, normals, tangents, texcoords) into
the memory of the graphics card, once and for all.
The mac-specific extension is really not an option sinc the code must
work on Linux, so I looked into ARB_vertex_buffer_object, and this is
really weird, but apple's developer website doesn't talk about it
(http://developer.apple.com/graphicsimaging/opengl/extensions.html),
and glxinfo on X11 doesn't give me that extension (any way to get the
opengl extensions without using glxinfo on X11 ?). When I read from
the spec you gave me, it says that this extension is used in OpenGL
1.4, but OS X.3 uses OpenGL 1.2.1... So where is this extension
hidden ?
ARB_vertex_buffer_object (aka VBO) was added in 10.3.4 and should be
supported on any card that already supports APPLE_vertex_array_range
(aka VAR). If you are running on a capable system, double check the
extensions list for it (not all ARB extensions are next to each other)
– but please do file a bug if its really not there.
Let me ring in here, too, that APPLE_vertex_array_range is a better
suited spec for certain circumstances, such as modifying a small sub
range of data for streaming. It has the ability to flush a sub range
of data when modified, whereas VBO requires at the very least a call
to BufferSubData (which means at least one more copy for non-cached
data) or flushing the entire range if you modify a piece of the data
manually via mapping (whew, did that make sense? ;-). The main
benefit that VBO provides over VAR is the ability to mix and match
multiple buffer objects (ie streamable vertex positions with static
texture coords). Since you are asking about statically caching data
on the video card, I think VBO should work out fine, but don't let
#ifdef's stop you from using a better suited API whenever applicable
(not just VAR vs VBO)!
Chris
Thanks for the advice Chris. I now updated to OS X.3.7, and I found the
extension in the list of supported extension. Thanks to the
documentation I was able to rewrite my code pretty fast to take
advantage of it, but now one problem arises : in what header is this
extension defined ?
I took a look in /System/Frameworks/Opengl.framework/header/glext.h but
it's just not there, although the oss.sgi.com website says it should be
right in there :|
Fred
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