Projection Matrix vs. Animation Speed
I am building a Mac OS X (Carbon) app to create scriptbased movies of a scaffold model (drawn using gluSphere and gluCylinder objects). The model is animated by manipulating the modelview â€“ rather than the projection â€“ matrix between each frame. The movie making process begins by setting an identity projection matrix (camera's lineofsight), which looks effectively into the zaxis (protruding from the monitor); the projection matrix remains untouched throughout the entire movie. The animation is quite choppy for even the simplest models. But if the projection matrix is set just a tiny bit off (from identity), then the animation moves about 10x more smoothly.
I find the animation is choppy anytime the projection looks directly into any of the axes (+/ x, +/ y, +/ z); any other arbitrary projection results in a very smooth animation.
Does anybody have a clue as to why such a small deviation in the projection matrix improves the animation so dramatically?
Thanks in advance.
 Jeff
I find the animation is choppy anytime the projection looks directly into any of the axes (+/ x, +/ y, +/ z); any other arbitrary projection results in a very smooth animation.
Does anybody have a clue as to why such a small deviation in the projection matrix improves the animation so dramatically?
Thanks in advance.
 Jeff
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