Re: [Algorithms] Representing Animation Key Frame with Quaternion+Translation Vector

[Jon W. <jw...@gm...>]

pontus birgersson wrote:
> I'm guessing it depends on the target plattform. Early rather crude 
> tests on my old GeForce 6800 told me that it might be worth sending a 
> bit more data in order to releave the vertex shader of the additional 
> reconstruction. Since since we're mainly targetting the Xbox 360 which 
> I've heard has a beast for vertex processor, the same will probably 
> not be true there.
>  

Why reconstruct a 4x4 for a bone matrix? You can blend the bones as 
three vector4s, and you can transform the vertex using three dot 
products. Only the projection matrix really needs a full 4x4.
The point about "sending more data" does not have to do with the data 
throughput, it has to do with how many bones you can cram into a single 
pass, without splitting your mesh. With 4x4 matrices, you can do about 
60; with 4x3 you can do about 80; with offset + quaternion you can do 
about 120!

Sincerely,

jw