SOFTIMAGE|3D expressions and constraints import into Softimage, but the order in which they are evaluated is different. For example, in SOFTIMAGE|3D you can apply a direction constraint to an object and also assign an expression to the object that controls its Y rotation. In Softimage, you can do this as well, but only the constraint will work.
When you import an object into Softimage that uses both a constraint and an expression, messages appear in the command log suggesting how you can replace the constraints with expressions so that the object will behave as it did in SOFTIMAGE|3D. For example:
WARNING : "3093 - The following expression(s) could be created to compensate for a constraint: WARNING : "3055 - PosConst_ExpY_1-0.cube1.kine.global.posx = PosConst_ExpY_1-0.cone1.kine.global.posx WARNING : "3055 - PosConst_ExpY_1-0.cube1.kine.global.posz = PosConst_ExpY_1-0.cone1.kine.global.posz WARNING : "3094 - CnsPos on cube1 could be replaced with the previous expression(s)
When importing scenes and models with expressions from SOFTIMAGE|3D, you should be aware of a slight difference that affects a small number of cases. With the distance functions ctr_dist, ctr_dist_cam, and ctr_dist_cam_int, SOFTIMAGE|3D does not evaluate past the object name. This means that in SOFTIMAGE|3D the following string is valid even if obj1 is not on a path:
ctr_dist(pref.obj1.trans, pref.obj2)
However, when the expression is imported, the result is invalid because Autodesk Softimage tries to resolve the path reference. To avoid this and similar problems, change pref.obj1.trans to pref.obj1 before importing.
Autodesk Softimage v.7.5