Having recently finished the port of a couple of games (Commandos 2 &
3) which do a large amount of in-level texture uploading, I can offer
the following advice.
-Stick to the standard Mac formats (8888 ARGB & 1555 ARGB or 422 YUV
for QuickTime movie data)
This avoids any pixel swizzling happening in the driver level which
will impact your performance (requiring a copy of the data in the
driver as well as the pixel swizzling itself).
ie:
internalformat = GL_RGBA8;
format = GL_BGRA_EXT;
type = GL_UNSIGNED_INT_8_8_8_8_REV;
for 8888 ARGB
internalformat = GL_RGB5_A1;
format = GL_BGRA_EXT;
type = GL_UNSIGNED_SHORT_1_5_5_5_REV;
for 1555 ARGB
internalformat = GL_RGBA;
format = GL_YCBCR_422_APPLE;
type = GL_UNSIGNED_SHORT_8_8_REV_APPLE;
for 422 YUV (QT movie data)
-Use rectangle textures
This is the current fast path for texturing on OS X. It does come with
some possibly severe limitations like no mipmaps and only clamped wrap
modes.
-Use client side storage
This removes another driver side copy of the data but does mean you are
now responsible for the data and will need to synchronize access to
that data.
// Set row pixels
glPixelStorei(GL_UNPACK_ROW_LENGTH, rowPixels);
// Set storage hint. Can also use GL_STORAGE_SHARED_APPLE see docs.
glTexParameteri(GL_TEXTURE_RECTANGLE_EXT,
GL_TEXTURE_STORAGE_HINT_APPLE , GL_STORAGE_CACHED_APPLE);
// Set client storage
glPixelStorei(GL_UNPACK_CLIENT_STORAGE_APPLE, GL_TRUE);
// Set proper state for rectangle textures
glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_MIN_FILTER,
GL_NEAREST);
glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_MAG_FILTER,
GL_NEAREST);
glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_WRAP_S,
GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_WRAP_T,
GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_RECTANGLE_EXT, 0, internalformat, Width,
Height,
0, format, type, pixelData);
// turn off client storage so it doesn't get picked up for the next
texture
glPixelStorei(GL_UNPACK_CLIENT_STORAGE_APPLE, GL_FALSE);
}
Assuming you will changing the texture data and re-uploading it to GL
using glTexSubImage2D, you will need to synchronize with the GL to
ensure that you do not change the texture data while the GL is using it
since we have used client storage.
There are a bunch of ways to do this but I found the most convenient to
be glFinishObjectAPPLE (which can be used for pretty much any of the GL
objects and not just texture objects). Basically, before you change the
texture data call:
// ensure any previous use of the texture has completed
glFinishObjectAPPLE( GL_TEXTURE, GLTextureID );
This will block until the GL has finished using the texture data, at
which point you are free to modify the data.
One other thing you can try is threading your texture uploads. Create a
shared context on a separate thread and use it to upload all of the
textures. The GL should handle the thread synchronization between the
shared contexts (ie. the shared threaded upload context and the other
shared contexts that would actually be using the textures. Remember
never access the same context from different threads). I have not tried
this approach yet although it is on my list of things to explore :)
On Apr 25, 2005, at 1:05 AM, Jonathan del Strother wrote:
I'm loading textures on-the-fly - a few hundred files from harddisk,
mostly around 300x300 pixels in size, as & when needed. I'm currently
using Quicktime (GetGraphicsImporterForFile, GraphicsImportDraw etc) -
I found this about 50% faster than loading the file into an NSImage ->
TIFFRepresentation -> NSBitmapImageRep.
I could do with some suggestions on speeding this up. Are there any
file formats which Quicktime will process faster than others? Any
resources discussing the fastest ways of uploading the texture data to
video? Any random tips I might be missing would be greatly
appreciated.
Cheers,
Jon
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