Curves

A curve is continuous line made of splines and lines. ppModeler allows mixing lines and curves in any way. There are 2D and 3D curves, and curves can be opened or closed.
2D closed curves can be grouped/ungrouped. A group of curves (eventually one) is called a shape. The inner curves of a shape define holes in the outer curve. That's why curves that intersect can't be grouped.

Two curves grouped...

defines a face with a hole.
Boolean operations can be performs on shapes. A Boolean operation is done by selecting two shapes, and press the csg button (). For example, the following 2 shapes
can be mix in the following ways:

Union of the two curves
The Boolean operation window is opened, where the user can select the appropriate operation (and preview the result), and if he/she wants to replace the two selected curves by the resulting one, or add the resulting curve without touching the two selected curves.

Intersection of the two curves

Substraction of one curve

Substraction of the other curve

XOR of the two curves
There are 4 different basic shapes ():
Text Curves
First, the user must point to a True Type Font file by clicking on the "Load..." button. Then, the text can be edited, and previewed. There are two parameters:
  • Resolution: the number of lines used to approximate a curve in the preview panel.
  • Scale: the relative scale of the text.

Editing Curves

The curve tools work at two levels. The curve level, where you can add basic curve, move, rotate, group and delete curves or shapes (see the curve toolbox) and the point level where you can edit the curves themselves (add, remove, and edit points and tangents (see the curve point toolbox)). A shape can be edited at the point level by Clicking on the point tool ().
When the user selects a point, the tangents are displayed. The user can then drag the point or the tangents ends. In the control panel, a dropdown button allows to move numerically the selected point, and also to change its continuity type.
There are 3 continuity types:
  • Corner: The two tangents (left and right) can be changed independently in length and direction.
  • Continuous: The two tangents must have the same direction, but a different length.
  • Smooth: The two tangents must have the same length and direction.