Fused CSG

The solid of Basic CSG built as a fused composition (see Fused composition): a shape whose type spells out the whole tree, evaluated with nothing to interpret. The source is at Examples/FusedCSG/main.cpp.

Building it fused

The functions in namespace Fused (EBGeometry_Fused.hpp) are the builder’s operations as types. They are called qualified (Fused::Union, not Union, which is the builder’s), and where the builder takes a std::vector they take the operands as arguments:

const auto fused = Fused::Difference(Fused::Intersection(cube, ball), drillX, drillY, drillZ);

Against the tape

The program builds the same solid through the builder and a Tape and prints both values at a point, which are the same to rounding, and the time per point of each on the host: the tape fetches and dispatches each clause, the fused solid has nothing to interpret.

Fused parts in a tape

A fused solid is one shape with one surface. Listed after T it is one leaf of a tape, so a scene known only at run time can place compiled parts, and closestPrimitive() names the part:

const Tape<T, FusedSolid> scene(pool, Union(Expr<T>(fused), Translate(Rotate(fused, 45, 1), Vec3(3, 0, 0))));

The same query on a GPU

The fused solid holds its shapes, not offsets into a pool, so it goes to the device as it is: GPU::transform(Distance<FusedSolid>{fused}, line, values), with nothing to mirror.

Looking at it

The example ends with Render::view(scene, pool, argc, argv), a window on the scene of two fused parts.

The window needs SDL2 and is built with make VIEWER=SDL2 or cmake -DEBGEOMETRY_VIEWER=SDL2 (see The viewer window (EBGEOMETRY_VIEWER)); otherwise, and with --no-view or without a display, view() prints why and returns. Drag to orbit and scroll to zoom; the window lists its other keys (see The viewer’s keys).

Building and running

See Building for how to compile it with CMake, GNU Make, or a direct compiler invocation, and Running on a GPU for a GPU build.

cd Examples/FusedCSG
./FusedCSG.ex