Help with C++ api example project.

[kurtsansom]

Description

I have made a cool thing with the studio app, but now I want to convert that to using the lower level C++ interface.

The example in the documentation kinda covers it, but do you an example using the c++ interface that creates and object and exports the stl based on some parametric input and has it's own cmake file that builds and links with library?

I know this is simple, but wanted to see if you had an example already around.

The Part I am getting stuck on is with cmake I typically use the find_package command, and am not sure how to deal with the pkgconfig files.

Thank you so much for sharing your work, and your time and effort.

[mkeeter]

Congrats on the cool thing – is it going to be made public eventually?

The easiest way to build on libfive right now is to include it as a Git submodule, then use add_subdirectory(libfive) to include it in the build. You can also use set(BUILD_STUDIO_APP OFF) in your top-level CMakeLists.txt (before add_subdirectory) so that the submodule only builds the core libraries and not the UI.

You can see an example of this in the mpr repo here.

[kurtsansom]

It’s pretty simple, and yes I would be happy to share it.

Thank you for the input and direction. -Kurt

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---

From: Matt Keeter [email protected] Sent: Tuesday, June 9, 2020 6:50 PM To: libfive/libfive Cc: kurtsansom; Author Subject: Re: [libfive/libfive] Help with C++ api example project. (#349)

Congrats on the cool thing – is it going to be made public eventually?

The easiest way to build on libfive right now is to include it as a Git submodule, then use add_subdirectory(libfive) to include it in the build. You can also use set(BUILD_STUDIO_APP OFF) in your top-level CMakeLists.txt (before add_subdirectory) so that the submodule only builds the core libraries and not the UI.

You can see an example of this in the mpr repohttps://github.com/mkeeter/mpr/ herehttps://github.com/mkeeter/mpr/blob/master/CMakeLists.txt#L5-L11.

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHubhttps://github.com/libfive/libfive/issues/349#issuecomment-641638827, or unsubscribehttps://github.com/notifications/unsubscribe-auth/ANP3TVTPAEMFXA7K2S27AHLRV3DE7ANCNFSM4NZZYEFA.

[kayarre]

It looks like the C++ api example is out of date from the current API?

I am having a hard time figuring out a simple example of a sphere and the steps required to generate the shape and export to stl.

[FunMiles]

I got a simple example running with the C++ API example. It does run but I have not visualized the result. I will do visualization in my own project.

#include <libfive.h>
#include <libfive/render/brep/mesh.hpp>
#include <libfive/render/brep/settings.hpp>

using namespace libfive;
int main()
{
	auto x = Tree::X();
	auto y = Tree::Y();
	auto z = Tree::Z();

	// Arithmetic is overloaded for the Kernel::Tree type
	auto out = (x * x) + (y * y) + (z * z) - 1;

	// Pick the target region to render
	auto bounds = Region<3>({-2, -2, -2}, {2, 2, 2});

	// Mesh::render returns a unique_ptr, so it cleans up automatically
	Mesh::render(out, bounds, BRepSettings{})->saveSTL("sphere.stl");

	return 0;
}

Note: I built the library separately and link to it. There is a big difficulty with the aligned allocator of Eigen. This allocator can default to the standard allocator depending of the compilation flags. The result is that the above code may calling the regular de-allocator on a vector that has been allocated by Eigen's aligned allocator, ending up in a crash.

My fix was to add -march=native to the compilation flags to be compatible with the ones the library will trigger from its CMakeLists.txt.

[FunMiles]

PS: I, like @kurtsansom am also for having an install that creates a proper CMake find_package compatible file. It's not terribly difficult to do with the recent CMake versions. I may create one if I have the time and will the do a PR.

[kayarre]

I couldn't get my example to work, I think I was missing the namespaces but I did get this to work.

/*
C++ example
*/
#include "libfive.h"

int main(int, char**)
{
    auto x = libfive::Tree::X();
    auto y = libfive::Tree::Y();
    auto z = libfive::Tree::Z();

    auto out = (x * x) + (y * y) + (z * z) - 1;
    libfive_region3 bounds = {{-2, 2}, {-2, 2}, {-2, 2}};

    std::cout << libfive_tree_print(&out) << std::endl;
    bool result;
    result = libfive_tree_save_mesh(&out,
                        bounds,
                        10,
                        "test.stl");
    std::cout << " did it work: " << result << std::endl;
}

I got yours to work, here's w/o namespaces. Yay!

	auto X = libfive::Tree::X();
	auto Y = libfive::Tree::Y();
	auto Z = libfive::Tree::Z();

	// Arithmetic is overloaded for the libfive::Tree type
	libfive::Tree t = libfive::Tree::X();
        t = min(sqrt((X + 0.5)*(X + 0.5) + Y*Y + Z*Z) - 0.25, sqrt((X - 0.5)*(Y - 0.5) + Y*Y + Z*Z) - 0.25);

	// Pick the target region to render
	auto bounds2 = libfive::Region<3>({-2, -2, -2}, {2, 2, 2});

	// Mesh::render returns a unique_ptr, so it cleans up automatically
	libfive::Mesh::render(out, bounds2, libfive::BRepSettings{})->saveSTL("sphere.stl");

[kayarre]

I decided to hack it a bit, and I think I have something that works. I will create a merge request in a bit mostly for as a way to get it out, but it has no polish. I am not a cmake expert. I have to relearn it every time I do it.