
Rotate object around its local coordinate system
Hi! I'm trying to rotate a 3d object (just a square plane) around ITS coordinate system, and not Processings global coordinate system. When using rotateX(), rotateY(), and rotateZ(), the rotation is always around Processings origo. I want to do a rotation around x at first, which is fine to use rotateX since it's the first rotation, and then rotate around the objects new yaxis. In other words, I want the rotation to always be around the object itself. So imagine there being a coordinate system on the square plane with zaxis orthogonal against the plane, and the x and yaxes in the plane (parallel).
I tried rotating around x first with rotateX, and then calculate a new yaxis (variable called new_vy) by multiplying the vector vy = {0, 1, 0} by x's rotational matrix, and then use rotate(angle, new_vy[0], new_vy[1], new_vy[2]);
Some semipsuedocode: //Code begin
rotateX(angleX);
new_vy = Rx(angleX)*vy; //Rx is the rotational matrix for xrotation. Note that this is a matrix operation,
//and the actual code doesn't look like this.
//vy is just the unit vector for the y axis, vy = {0, 1, 0}
rotate(angleY, new_vy[0], new_vy[1], new_vy[2]); //this function is pretty much the same as glRotatef(angle, x, y, z);
draw3dobject();
//Code end
This should be done for z aswell, but x and y is enough for starters.
So, any suggestions? Doesn't have to be a modification to my code, can be an entirely different method.
I've found something about quaternions, but I would prefer not to use them, since I don't entirely understand them, and I think that this should work with out them.
The purpose of this is to simulate a quadcopter, so therefor I need to input three separate angles, pitch, roll yaw, (euler angles).
/Daniel
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