(3ds max SDK) How do I get the node of a Control?

Question

I am implementing a LookAt Controller plugin by deriving from the Control class.

Everything works fine, except that I don't understand how I can get a INode pointer to the node that the Control belongs to. How do I get this pointer? (I need to access the pointer from within the code of my LookAt class.)

Answer 1

Don't get the node pointer. Controls shouldn't know how their values are being used, just take your inputs, apply your algorithm to it, and return the value.

For example, to create a LookAt, I would define my Control to be of superclass type CTRL_ROTATION_CLASS_ID. When this control evaluates (GetValue is called with method = CTRL_RELATIVE), it will be passed a pointer to the transform you want to apply your value to. Assuming your rotation is part of a PRS, then the transform will be the parents transform, + the Position part of the (P)RS.

void YourClass::GetValue(TimeValue t, void* val, ...)
{
    Matrix3* pInTransform = reinterpret_cast<Matrix3*>(val);
    Point3& pMyPosition = pInTransform->GetTrans();

With the position, you can get the position of your target, then rotate/set that input matrix so your eye vector points at the target

I'd highly recommend the learning path section of the documentation for a general understanding of how the animation hierarchy in Max works.

http://docs.autodesk.com/3DSMAX/15/ENU/3ds-Max-SDK-Programmer-Guide/files/GUID-A39314EC-15B4-4919-BB1B-318FFDC05DD8.htm