Use assimp as mesh importer and exporter

[ghost]

Use assimp to be able to import and export mesh instead of custom code.

Currently just replacing the obj import and export function, but maybe updated later to be more generic

[simogasp]

Maybe add the cmake code to build assimp like the other libs

    set(ASSIMP_TARGET assimp)
    set(ASSIMP_BUILD_OPTIONS -DASSIMP_BUILD_ASSIMP_TOOLS:BOOL=OFF -DASSIMP_BUILD_TESTS:BOOL=OFF)
    set(ASSIMP_AV_VERSION 5.0.1)
    set(ASSIMP_FILENAME v${ASSIMP_AV_VERSION}.tar.gz)
    ExternalProject_Add(${ASSIMP_TARGET}
            URL https://github.com/assimp/assimp/archive/${ASSIMP_FILENAME}
            DOWNLOAD_NAME assimp-${ASSIMP_FILENAME}
            PREFIX ${BUILD_DIR}
            BUILD_IN_SOURCE 0
            BUILD_ALWAYS 0
            SOURCE_DIR ${CMAKE_CURRENT_BINARY_DIR}/assimp
            BINARY_DIR ${BUILD_DIR}/assimp_build
            INSTALL_DIR ${CMAKE_INSTALL_PREFIX}
            CONFIGURE_COMMAND ${CMAKE_COMMAND} ${CMAKE_CORE_BUILD_FLAGS} ${ASSIMP_BUILD_OPTIONS} -DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR> <SOURCE_DIR>
            )
    set(ASSIMP_CMAKE_FLAGS -DAssimp_DIR:PATH=${CMAKE_INSTALL_PREFIX}/lib/cmake/assimp-${ASSIMP_AV_VERSION}/)

Verify the last line as I cannot check if it still installs assimp in a folder named assimp-${ASSIMP_VERSION}

[simogasp]

Suggested change

	pts.push_back(Point3d(v.x, v.y, v.z));
	pts.emplace_back(v.x, v.y, v.z);

requires to add the wrapper method to StaticVector (I think it's worth it because if we ever manage to replace StaticVector with a "pure" std:vector (ie not as member of the class) everything will be smooth)

[simogasp]

I think adding this to StaticVector should work

    template< class... Args >
    void emplace_back( Args&&... args )
    {
        _data.emplace_back(std::forward<Args>(args)...);
    }

[simogasp]

Suggested change

	int vertexId = p.first.first;
	int uvId = p.first.second;
	const int vertexId = p.first.first;
	const int uvId = p.first.second;

[simogasp]

Suggested change

	int triangleId = _atlases[atlasId][i];
	const int triangleId = _atlases[atlasId][i];

[simogasp]

Suggested change

	for(int i = 0; i < _atlases[atlasId].size(); i++)
	for(int i = 0; i < _atlases[atlasId].size(); ++i)

[simogasp]

Suggested change

	int vertexId = mesh->tris[triangleId].v[k];
	int uvId = mesh->trisUvIds[triangleId].m[k];
	const int vertexId = mesh->tris[triangleId].v[k];
	const int uvId = mesh->trisUvIds[triangleId].m[k];

[simogasp]

Suggested change

	for (int k = 0; k < 3; k++)
	for (int k = 0; k < 3; ++k)

[simogasp]

Suggested change

	if (_atlases.size() == 0)
	if (_atlases.empty())

[fabiencastan]

Is there a way to add a message in the OBJ file that it has been generated with AliceVision and specify the version?
Currently it says only assimp and the version of assimp.

[simogasp]

Is there a way to add a message in the OBJ file that it has been generated with AliceVision and specify the version?
Currently it says only assimp and the version of assimp.

I think you can add it in the aiMetadata
https://assimp-docs.readthedocs.io/en/master/API/API-Documentation.html#_CPPv410aiMetadata

code updated

[fabiencastan]

I'm merging it for now.
@servantf Can you check if we can add metadata in a new PR?

[ghost]

There is no way to add metadata in obj files.
aiMetadata are almost never exported but used for importers.
A solution may be to fork assimp and modify it ?