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Shaping Options

We have discussed almost everything about shaping. There is left a section here called Shaping Options. This section is responsible of a few important options which control how the model will react to shaping actions.

Elasticities

Let's start with elasticities. If you pick a vertex and move it, the edges attached to it change shape. Let's look at this edge for instance. This happens because one side of the edge is changing, while the other side of the edge is not. This is pretty much common in graphics softwares which use curves. Here in Curved Poly, you can ask the editor to do something about this. Elasticities indeed controls the way in which edges reacts to reshaping actions.

The most simple option, but not the most reccomended, here, is Clayish mode. In Clayish mode, the edge does not react to shaping at all. This is waht happens in most of the other graphics tools around, so we think you should used to it.

The other elasticities works in this way: they change the lenght of the handles of the edge, to match some shaping action. So if I move this vertex, with this handle picked, the handle change its length during the process.

So, with the Proportional mode, active by default, if the lenght of an edge decreases, also the length of the handles decreases. Proportional mode follow the principle of keeping the shape of the edge the way it is, under some transforms, by scaling the edge proportionally.

The opposite to Proportional is Elastic. In elastic mode, when an edge length would increase, the handles react like springs reducing their length, and if the edge length decreases, the handles react by increasing their length. The principle here is to make the edge work like a spring indeed, making its shape change drastically to match as much as possible the original length.

Last, but not least, we have the Elliptic elasticity. This works works in a way which is similar to proportional, but it stretches the shape of the edges such that elliptic arcs keep being elliptic arcs, so it works very well on shapes which has been designed to have circles or ellipses.

Furthermore, while you are shaping a group of elements, you can try out the elasticities and choose the one which looks better for you. To do so, you just transform your selection a bit, then you go to Shaping Options and change the elasticity mode. This will recompute the transform on the selection, updating the edges which are affected by elasticities settings.

Edge Normal

Another important group of tools here, are the ones which control editing normals on groups of elements. We have already covered the role of editing normals, both on vertices and on edges. As you can see here, we have three options which are similar to the ones used for edges normal. The difference is that, like elasticities, these options applies by default on all edges which are changing shape. Again, by default the option here is the Axis Normal, which is usually the best solution, but you could try to work with the others.

Each curved edge has as a Normal vector assigned to its center. This normal may be used by the Interpolation/Filling Algorithms to correct the orientation of polygons across the edge, so it's very important that you understand what you can do to correct its orientation.

When an edge is reshaped, its normal must be recomputed. Here are the algorithms which are automatically applied during the process.

Axis Normal (Default-Optimal Choice): an algorithm which takes into accounts the shape of the Edge, the two editing normals on the two extremes vertices and also the direction of other edges nearby the extremes. Such direction is called the Axis. Axis Normal is more correct to use in situation where there are sharp angles between edges.

Edge Normal: an algorithm which takes into accounts only the shape of the Edge and the two editing normals on the two extremes vertices.

Balance Normal: an algorithm which takes into account the shape of the Edge, the two editing normals on the two extremes vertices and also the position of any opposite edge (for quads) or opposite vertex (for triangles) on adjacent polygons. The Editing Normal will be perfectly balanced between the two opposite positions: this is correct on spherical surfaces equally subdivided (as it is for spherical primitives) .

Reset Normals: reset edges normals on all selected edges.

Fix Normals: recompute all the normals, both the ones on vertices and then the ones on edges. Best used when something looks weird in the way edges normals are assigned.

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