# The Industry's Foundation for High Performance Graphics

1. ## Math behind gluLookAt

Does anyone know how to convert a forward vector from the camera to angles?

By that i mean, the camera is looking in the direction of a normalized vector. Instead of using gluLookAt, how can i convert this vector to angles.

2. ## Re: Math behind gluLookAt

Project the vector to each plane and work out the angle to the axis.

for ex. if you have the vector (1,2,3), then consider the angle of the vector (1,2) on the Z plane (ie. theta1=arctan(0.5)). this is the rotation about the y-axis.
Similarly, projecting the vector onto the X plane gives theta2=arctan(2/3); Thus, the requried rotation is

glRot(arctan(2/3), 1.0, 0.0, 0.0);
glRot(arctan(0.5), 0.0, 1.0, 0.0);

you can't recover z rotation (since it isn't specified). I hope the maths is right. ;-) but the idea should be sound: projection to recover one angle.

Hope this helps,

cheers,
John

3. ## Re: Math behind gluLookAt

Thanks, ill give it a go asap

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