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What's the meaning of m34 of the structure CATransform3D, I only know it can change the perspective, but what's the meaning when the value is -0.001 and 0.001?

A: 

Well, this +/- set up by apple, it's related to optical perspective, when the value is + plus, the perspective (3D object projects on 2D surface) is larger when it's near the spot point; smaller when it's far from the spot point. This is what we feel regular, our eyes and brain works with space like this. another one is -, minus, this is the strange one, exactly opposite to the + one, far object seems Larger, nearby object seems Smaller. I remember many art works has this perspective. That's + & -. and 0 is the infinite distance perspective between object and spot point, which is parallel perspective. hope this helps. better wiki it.

flutewang