[Bf-committers] Shapes / Shape Keys - confusing terminology

[Roger Wickes]

+1 Shape. KISS, people!

In Blender, an object can have many different Shapes. The ultimate shape of an object that you see in the 3D view or in a render is a blend of its Basis Shape and any other Shapes that exert an influence on that Basis Shape, and thus exert some effect the overall shape of the object. Each Shape is defined by the location and other properties of its defining points: for mesh objects, the vertex location; for NURBS objects, the control points, and for curves, the bezier handles.  A special note is that if an object is used in a special way, such as a Bevel Object to bevel a Curve, then as the shape of the Bevel Object changes, the modified shape of the Beveled Curve will change as well. 

Taking the mesh object as a simple example, the Basis shape for a human head may be a neutral, expressionless face. We then create a new Shape, editing the mesh to shape a smile for the mouth, and call that the "Happy" Shape. To go from a neutral expression to a smiling expression on the face, we (over time) increase the influence of the "Happy" Shape over the Basis Shape, eventually decreasing the Basis Shape influence to zero while at the same time increasing the influence of the Happy Shape to 1.0. The position of a vertex at any time is a blend of the Basis shape position and the position of that vertex in all the other Shapes, weighted by the total of all Shape's influence. For example, suppose, in the Basis Shape, a vertex's location was (0,0,0) and in the Happy Shape it was (2,2,0). If on frame 5 the Basis Shape is keyed to have an influence weight of 1.0, and the Happy Shape is keyed to 0.0 influence, the vertex location would be [1*(0,0,0) + 0.0
 *(2,2,0) ] / (1+0), or (0,0,0). If both the Basis and the Happy Shape had a weight of 1.0, the vertex location would be [1*(0,0,0) + 1*(2,2,0)]/(1+1), or (1,1,0) - half-way in-between the two shapes. By keying the influence of each Shape in time, you control the net shape of the object at each frame.

Makes grammatical and logical sense to me...