Well, thought that subject would make you look here... Now to the problem: I''m trying to write a 3D editor, such as QOOLE for quake, etc... I made a CFace3 class (which is a triangle), and a CFace4 (which is a quad, derived from CFace3).
Each CFace can move, stretch itself, and find its centre point. I use a matrix to stretch/move them
There''s also a CPolygon class which stores arrays of CFace''s, and is sort of a message router, when u move something on the X axis, it goes through its own CFace3 array and calls CFace3::MoveX(), then through its CFace4 array and calls CFace4::MoveX() for each CFace4.
Now I''m up to making them rotate (well have been up to this for about a week and a half!). I (for some weird reason) didnt make a rotate function for the CFace''s, but only in CPolygon, which creates a rotation matrix depending on the axis you are rotating on, and multiplies each vertex of each CFace3/4 by this matrix. Now, problem is, if the CPolygon isnt centred at (0,0,0), when you rotate the polygon, it sorta orbits this origin (Its obvious to me why, that''s not my question
). To make it rotate each CPolygon properly, I made it find the centre of the CPolygon, move it by - of that value (which effectively moves it to (0,0,0)), and then rotated it, and then moved it back to where it came from...
This sorta works, except that it doesnt
... Somehow a rounding error or something creeps in somewhere, (I''m suspecting the GetCentrePoint() function of the CPolygon) and after a few rotates, it doesnt centre itself on (0,0,0) any more and it starts the orbiting thing again.
Does anyone know of any other way to rotate the polygons so they dont orbit but rotate about their own centre point??? Its been driving me mad for over a week now, no sleep, eyes red, etc... I just cant think of any other way to rotate them other than moving to the origin then back.
Here''s my code for making a rotation matrix:
void Mat4::CreateRotation(float angle, bool xRot, bool yRot, bool zRot)
{
float ca = cos(angle*PI_OVER_180);
float sa = sin(angle*PI_OVER_180);
float x = 0;//pt.getX();
float y = 0;//pt.getY();
float z = 0;//pt.getZ();
if(xRot==true)
{
m[0][0]*=1; m[0][1]*=0; m[0][2]*=0; m[0][3]*=0;
m[1][0]*=0; m[1][1]*=ca; m[1][2]*=-sa; m[1][3]*=0;
m[2][0]*=0; m[2][1]*=sa; m[2][2]*=ca; m[2][3]*=0;
m[3][0]*=0; m[3][1]*=0; m[3][2]*=0; m[3][3]*=1;
}
if(yRot==true)
{
m[0][0]*=ca; m[0][1]*=0; m[0][2]*=-sa; m[0][3]*=0;
m[1][0]*=0; m[1][1]*=1; m[1][2]*=0; m[1][3]*=0;
m[2][0]*=sa; m[2][1]*=0; m[2][2]*=ca; m[2][3]*=0;
m[3][0]*=0; m[3][1]*=0; m[3][2]*=0; m[3][3]*=1;
}
if(zRot==true)
{
m[0][0]*=ca; m[0][1]*=-sa; m[0][2]*=0; m[0][3]*=x;
m[1][0]*=sa; m[1][1]*=ca; m[1][2]*=0; m[1][3]*=y;
m[2][0]*=0; m[2][1]*=0; m[2][2]*=1; m[2][3]*=z;
m[3][0]*=0; m[3][1]*=0; m[3][2]*=0; m[3][3]*=1;
}
}
Maybe the rotate matricies are wrong??? Any ideas would be greatly appreciated
