Raab, Andreas Andreas.Raab@disney.com
In fact, if you look closely at Squeak-Alice then you'll notice that Squeak-Alice *is* a retained mode framework - and a pretty good one at this because it allows you to script arbitrary objects in the 3D world. That it is currently not at the same speed as other retained mode frameworks has nothing at all to do with Squeak-Alice. It is the immediate mode stuff which drops us in the framerate
- everything in Squeak is currently run from software only, there is no
hardware accelleration at all.
Hmmm...
What is the overhead of the retained-mode portion? My impression is that once you DO get hardware acceleration support, the fact that the retained-mode database is interpreted WILL be noticeable. In fact, I suspect that it already is noticeable in some cases.
------------------------------------------------------------------------- Lawson English. Squeak, snore, etc. Check out http://www.squeak.org -------------------------------------------------------------------------
At 07:57 AM 7/28/99, Lawson English wrote:
What is the overhead of the retained-mode portion? My impression is that once you DO get hardware acceleration support, the fact that the retained-mode database is interpreted WILL be noticeable. In fact, I suspect that it already is noticeable in some cases.
The most time consuming operations in Squeak-Alice are the matrix transformations, specifically matrix multiplication and inverting matrices. When you're running an animation, every frame Alice needs to determine the new composite matrix (and resize matrix, if necessary) for the animated object. So the more animations you're running, the more matrix math the system needs to do, and the slower it goes. The most computationally expensive operations that Alice performs are probably the animations that work in other reference frames, because this requires walking up the scene graph from the reference object (inverting matrices all the way) and then walking back down it to the affected object to determine the relative composite matrix.
Luckily a lot of this stuff is amenable to pushing down into C, so if Andreas or I (or other interested parties) get time we can push some of the bottlenecks down.
Jeff
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