SHAPE_POLY_SET: fix crash in VertexCount when it is a empty poly set, or when params are incorrect.
minor other fixes:
warning in degug mode in dialog_dxf_import_base.cpp
pcb_painter.cpp: remove a useless debug line.
Removes the need of using the legacy code in polygon/PolyLine.{h,cpp},
refactoring all CPolyLine instances with SHAPE_POLY_SET instances.
The remaining legacy methods have been ported to SHAPE_POLY_SET;
mainly: Chamfer, Fillet, {,Un}Hatch.
The iteration over the polygon vertices have been simplified using the
family of ITERATOR classes.
* Split and rewrite the preview window and canvas.
* Create a new class for handling the board information.
* Adds new render targets: openGL, legacy, and ray tracing.
* Render targets take full advantage of the new 3D plugins system and 3D cache
for a fast 3D model loading.
* Faster board loading.
* New OpenGL render is faster than the old one.
* New ray tracing render target with a post processing shader.
* Use of new 3D plugins (WRL, X3D, STEP and IGES) and 3D model caching.
* Preview of 3D model while browsing the file name.
* 3D preview of the footprint while adding / align 3D shapes.
* Render of 3D models according to attributes: Normal, Normal+Insert, Virtual.
* Pivot rotation centered in one point over the PCB board.
* Shortcuts keys improved for XYZ orientation..
* Animated camera.
In polygon calculations (combining polygons, fracture) the mode of calculation (fast or strictly simple polygon option) as no more a default value, because choosing the best mode is better to optimize the calculation time.
In 3D viewer, this option can take a *very long* calculation time (minutes instead of seconds, or hangs) and they are now using aFastMode = true to do polygon calculations, especially for zones inside zones belong to the same net but having different priority (which creates weak polygons).
aFastMode = false is the default for other calculations (zone filling) as before.