Better documentation of lookAt and headsUp

[Germanunkol]

Description

In the documentation, the lookAt and headsUp functions (and their various overloads) could use some more explanation, I think.

Here are some questions I had that the Docs dont't answer, in my opinion:

• What's the difference between NodePath.lookAt( point, up ) and Nodepath.headsUp( point, up )?
• What space are the point and the up vector in?
• How does this change when adding the other argument? (I found out the hard way that up stays in the node path's parent's space)

[rdb]

For the record, documentation of heads-up:

Given two vectors defining a forward direction and an up vector, constructs the matrix that rotates things from the defined coordinate system to y-forward and z-up. The up vector will be rotated to z-up first, then the forward vector will be rotated as nearly to y-forward as possible. This will only have a different effect from look_at() if the forward and up vectors are not perpendicular.

Documentation of look-at:

Given two vectors defining a forward direction and an up vector, constructs the matrix that rotates things from the defined coordinate system to y-forward and z-up. The forward vector will be rotated to y-forward first, then the up vector will be rotated as nearly to z-up as possible. This will only have a different effect from heads_up() if the forward and up vectors are not perpendicular.

So, one will prefer aligning the object with the Y axis, the other will prefer aligning it with the Z axis.

The other argument works like it does in other NodePath operations: it indicates which space the other parameters are relative to, the default being the NodePath's own parent.

I am not sure where exactly in the manual this information would fit, did you have a suggestion?