Avendish geometry / mesh template

This provides a basic, canonical template for making geometry / mesh objects with Avendish: a single C++ object that generates a mesh and is compiled, without rewrite, to several host plug-in formats.

It is the geometry counterpart of the audio processor template: where that one ticks per audio buffer and processes samples, this one ticks per frame and produces a mesh (vertices, normals, colors, indices) on its output.

What gets built

The avnd_make_geometry(...) macro in CMakeLists.txt instantiates the geometry back-ends. From src/Model.hpp you get:

Back-end	Object kind	SDK required
TouchDesigner SOP	Surface Operator	TouchDesigner Custom Operator SDK
TouchDesigner POP	Particle Operator	TouchDesigner Custom Operator SDK
Godot	GDExtension node producing an ArrayMesh	none — godot-cpp is fetched automatically
ossia score	geometry process	libossia

Back-ends whose SDK is not provided are silently skipped, so you can build just the ones you need.

Note on Max/MSP: Max is intentionally not a geometry target. Max's Avendish binding (Jitter) only handles matrix / texture outputs and rejects geometry output ports at compile time, so a geometry object cannot be emitted for Max. Use the audio/message template for Max objects.

The object

src/Model.hpp / src/Model.cpp implement MyGeometry, a generator that emits a subdivided plane mesh displaced by a sine wave, with controllable size, subdivision count, displacement height and color. It writes positions, normals, per-vertex colors and a triangle index buffer into a halp::position_normals_color_index_geometry output.

Start from there: change the ports in the inputs struct, and rewrite operator() to fill the mesh buffers however you like. See examples/Tutorial/CubeGenerator.hpp in Avendish for the canonical reference, and halp/geometry.hpp for the other ready-made mesh layouts (position-only point clouds, packed/interleaved attributes, per-attribute buffers, fully dynamic run-time geometry, …).

Building

cmake -S . -B build -G Ninja \
  -DCMAKE_BUILD_TYPE=Release
cmake --build build

With no extra options this builds the Godot back-end (it fetches godot-cpp automatically). To enable the other back-ends, pass the relevant SDK paths below.

To see a complete build procedure, refer to the Github actions workflows, which compile the project on clean virtual machines.

Godot

godot-cpp is fetched via CMake FetchContent by default. To build against an existing checkout instead, pass:

-DGODOT_CPP_PATH=path/to/godot-cpp

The build produces build/godot/my_geometry_geo.{so,dll,dylib} and a matching .gdextension file you can drop into a Godot project.

TouchDesigner (SOP + POP)

Point CMake at a TouchDesigner Custom Operator SDK whose include/ directory contains the operator base headers. Avendish reads ${TOUCHDESIGNER_SDK_PATH}/include/:

-DTOUCHDESIGNER_SDK_PATH=path/to/CustomOperatorSamples

This produces a TouchDesigner SOP (build/td/...SOP...) and a TouchDesigner POP (build/td/...POP...).

• The SOP back-end only needs CPlusPlus_Common.h + SOP_CPlusPlusBase.h, present in the public TouchDesigner/CustomOperatorSamples.
• The POP back-end is experimental and additionally needs POP_CPlusPlusBase.h plus the POP-enabled CPlusPlus_Common.h, which Derivative ships only inside the experimental TouchDesigner installation (Samples/CPlusPlus). The jcelerier/CustomOperatorSamples fork bundles these under include/, so pointing TOUCHDESIGNER_SDK_PATH at a checkout of that fork builds both SOP and POP. This is what the CI does.

Note: TouchDesigner uses the MSVC ABI on Windows — build with clang-cl or MSVC, not MinGW (the CI builds the TouchDesigner back-ends on Linux and macOS with Clang).

ossia score

Install libossia (or build score and point CMake at its 3rdparty tree) so that find_package(ossia) succeeds; the geometry process then becomes available inside ossia score.

TODO

• Support importing the template with a package manager
• Max/MSP (Jitter) mesh output