Millionth Camera question

um...here

typedef union {
 struct {
VECTOR right;		//X vector
GLfloat pad_0;	
VECTOR up;		//Y vector
GLfloat pad_1;	
VECTOR dir;		//Z vector
GLfloat pad_2;	
VECTOR pos;		//pos vector
GLfloat pad_3;
};
 GLfloat m[16];} UMATRIX;
 

And remember, the camera is the inverse of this.

>> 0 -r.z r.y
r.z 0 -r.x
-r.y r.x 0<<

?? are u trying to combine your rotation matirces together? u have to first do one + then do the next eg rotate first around the x axis + then around the y axis (ie u cant go rotate x+y together)

http://uk.geocities.com/sloppyturds/gotterdammerung.html

>> 0 -r.z r.y
r.z 0 -r.x
-r.y r.x 0<<

That builds a rotation matrix for a rotation around an arbitrary axis. I use it to rotate around the camera's right vector for looking up and down, as opposed to using the x axis, because if the camera is rotated then the x axis might be running through the camera, and I'd get a roll instead.

Edited by - outRider on February 6, 2002 9:25:19 AM

Anyhow, I pulled out a piece of paper and started visualizing everything. It seems to me that to rotate the camera left/right I should use the y axis, not the camera''s up vector, since to simulate human head movement up would always be up, unless your whole body changes orientation. To rotate up/down I should use the camera''s right vector, not the x axis, since if I rotate the camera left/right 90deg the x axis would not be to the right of the camera and might be where the z axis is and I''d get a roll. Well, I''ve tried this and it doesn''t seem to work. Even on paper, rotating through the y axis left 90deg, then rotating up or down through the right vector produces a roll. I''ve worked it out on paper, and it seems to work.

Here''s what I did

Cam pos (0, 0, 0) R (1, 0, 0) U (0, 1, 0) F (0, 0, 1) cos90 0 sin90 1 0 0 Ry = 0 1 0 Cam = [R|U|F] = 0 1 0 -sin90 0 cos90 0 0 1 0 0 1 Ry * Cam = 0 1 0 -1 0 0

So that''s rotated the camera 90 degrees to its left, next, if I want to rotate up I''d rotate through the x axis, but the camera''s forward vector should be the x axis now and that should produce a roll, so intead I rotate through the camera''s right vector. To build a rotation matrix for the right vector I use the above formula, I + sin(angle)*S + (1-cos(angle))*S^2. (I realize that since the right vector is now mapped to the z axis I should get a matrix for a rotation around the z axis, which I do)

0 1 0 0 0 1 Rright = -1 0 0 Cam = 0 1 0 0 0 1 -1 0 0 0 1 0 Rright * Cam = 0 0-1 -1 0 0

Now the forward and up vectors has been rotated down 90deg. Though it works fine there, it doesn''t work when I actually use it in my app. Is this a correct way to do it? If so I''ll have to see if it''s something else thats screwing things up. If anyone has any insight on where the problem might be I''d appreciate it.

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- outRider -