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