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Rotation from Normal?

Started by miketavius Dec 8, 2001 at 1:22 AM 0 replies 850+ views

Original Post

Dec 8, 2001 at 1:22 AM

I''m currently working on a futuristic racing game similar to f-zero (but of course in 3d), and I need to somehow retrieve a rotation matrix from a plane normal (the track), so I can apply it to the car. It looks quite silly when the car travels up the track, or on a ramp... and stays perfectly flat

I''m using OpenGL, so I need the rotation matrix to be in column major form. I''m posting this as a last resort, cuz I''ve been searching the forums all night, but have yet to find a definitive answer to my question. Any help would be appreciated!!!

henryx

Dec 8, 2001 at 5:09 AM

You need more than just the plane normal to get the car''s rotation matrix. However, if you know the cars direction in the x-z plane - which I assume that you have to point the car in the correct direction then you can build a rotation matrix from that info.

The up vector (U) of the car is the plane normal.

You already know the x and z component of the direction vector (D) for the car so from U.D = 0 you can find the z component of D.

Normalise D then the right vector (R) for the car is R=DxU.

You now hae all three vextors for the rotation matrix and can build it. Remember to add in the positional components as well.

I haven''t tried this out but hopefully it will get you going in the right direction (sorry about the pun).

henry

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