How to set up Assimp for Qt6 MinGW 64-bit to run on WebAssembly

[8Observer8]

The next steps work for me (after I added C:\emsdk\upstream\emscripten to the Path variable):

cd assimp-5.2.5 && mkdir build && cd build
emcmake cmake ..
emmake make

These commands generated the libassimp.a library:

I try to set up this library in Qt Creator like this:

INCLUDEPATH += "E:/libs/assimp-5.2.5/include"
LIBS += -L"E:/libs/assimp-5.2.5/build/lib"
LIBS += -lassimp

I had this error: error: 'assimp/config.h' file not found. I solved this error by copying this file E:\libs\assimp-5.2.5\build\include\assimp\config.h to this directory: E:\libs\assimp-5.2.5\include\assimp.

Issues: :-1: error: [Makefile:69: .\load-with-assimp-wasm-opengles2-qt6-cpp.js] Error 1 But I have already built another examples with OpenGL ES 2.0 to WASM without the problem.

Compiler output:

15:56:34: Running steps for project load-with-assimp-wasm-opengl2-qt6-cpp...
15:56:34: Starting: "C:\Qt\6.7.0\wasm_singlethread\bin\qmake.bat" E:\_Projects\LoadingModels\load-with-assimp-wasm-opengl2-qt6-cpp\load-with-assimp-wasm-opengl2-qt6-cpp.pro -spec wasm-emscripten "CONFIG+=debug" "CONFIG+=qml_debug"
15:56:36: The process "C:\Qt\6.7.0\wasm_singlethread\bin\qmake.bat" exited normally.
15:56:36: Starting: "C:\Qt\Tools\mingw1120_64\bin\mingw32-make.exe" -f E:/_builds/build-load-with-assimp-wasm-opengl2-qt6-cpp-WebAssembly_Qt_6_7_0_single_threaded-Debug/Makefile qmake_all
mingw32-make: Nothing to be done for 'qmake_all'.
15:56:36: The process "C:\Qt\Tools\mingw1120_64\bin\mingw32-make.exe" exited normally.
15:56:36: Starting: "C:\Qt\Tools\mingw1120_64\bin\mingw32-make.exe" -j4
C:\Qt\6.7.0\mingw_64\bin\qmake6.exe -install sed -e s/@APPNAME@/load-with-assimp-wasm-opengl2-qt6-cpp/g -e s/@APPEXPORTNAME@/load_with_assimp_wasm_opengl2_qt6_cpp_entry/g -e s/@PRELOAD@//g C:/Qt/6.7.0/wasm_singlethread/plugins/platforms/wasm_shell.html > E:/_builds/build-load-with-assimp-wasm-opengl2-qt6-cpp-WebAssembly_Qt_6_7_0_single_threaded-Debug/load-with-assimp-wasm-opengl2-qt6-cpp.html
copy /y C:\Qt\6.7.0\wasm_singlethread\plugins\platforms\qtloader.js E:\_builds\build-load-with-assimp-wasm-opengl2-qt6-cpp-WebAssembly_Qt_6_7_0_single_threaded-Debug
copy /y C:\Qt\6.7.0\wasm_singlethread\plugins\platforms\qtlogo.svg E:\_builds\build-load-with-assimp-wasm-opengl2-qt6-cpp-WebAssembly_Qt_6_7_0_single_threaded-Debug
        1 file(s) copied.
        1 file(s) copied.
em++ -s 'ASYNCIFY_IMPORTS=qt_asyncify_suspend_js,qt_asyncify_resume_js' -s WASM=1 -s MAX_WEBGL_VERSION=2 -s ERROR_ON_UNDEFINED_SYMBOLS=1 --bind -s FETCH=1 -s MODULARIZE=1 -s WASM_BIGINT=1 -s STACK_SIZE=5MB -g2 -s WASM=1 -s MAX_WEBGL_VERSION=2 -s ERROR_ON_UNDEFINED_SYMBOLS=1 --bind -s FETCH=1 -s MODULARIZE=1 -s WASM_BIGINT=1 -s STACK_SIZE=5MB -s DEMANGLE_SUPPORT=1 --profiling-funcs -s EXPORTED_RUNTIME_METHODS=UTF16ToString,stringToUTF16,JSEvents,specialHTMLTargets,FS -s EXPORT_NAME=load_with_assimp_wasm_opengl2_qt6_cpp_entry -sALLOW_MEMORY_GROWTH -s INITIAL_MEMORY=50MB C:/Qt/6.7.0/wasm_singlethread/lib/libQt6BundledFreetype.a C:/Qt/6.7.0/wasm_singlethread/lib/libQt6BundledLibpng.a -o .\load-with-assimp-wasm-opengl2-qt6-cpp.js   @object_script.load-with-assimp-wasm-opengl2-qt6-cpp.js
wasm-ld: error: E:/libs/assimp-5.2.5/build/lib\libassimp.a(AssbinLoader.cpp.o): undefined symbol: uncompress
wasm-ld: error: E:/libs/assimp-5.2.5/build/lib\libassimp.a(Compression.cpp.o): undefined symbol: inflateInit_
wasm-ld: error: E:/libs/assimp-5.2.5/build/lib\libassimp.a(Compression.cpp.o): undefined symbol: inflateInit2_
wasm-ld: error: E:/libs/assimp-5.2.5/build/lib\libassimp.a(Compression.cpp.o): undefined symbol: inflate
wasm-ld: error: E:/libs/assimp-5.2.5/build/lib\libassimp.a(Compression.cpp.o): undefined symbol: inflate
wasm-ld: error: E:/libs/assimp-5.2.5/build/lib\libassimp.a(Compression.cpp.o): undefined symbol: inflate
wasm-ld: error: E:/libs/assimp-5.2.5/build/lib\libassimp.a(Compression.cpp.o): undefined symbol: inflateReset
wasm-ld: error: E:/libs/assimp-5.2.5/build/lib\libassimp.a(Compression.cpp.o): undefined symbol: inflateSetDictionary
wasm-ld: error: E:/libs/assimp-5.2.5/build/lib\libassimp.a(Compression.cpp.o): undefined symbol: inflateEnd
wasm-ld: error: E:/libs/assimp-5.2.5/build/lib\libassimp.a(Compression.cpp.o): undefined symbol: inflateEnd
wasm-ld: error: E:/libs/assimp-5.2.5/build/lib\libassimp.a(Compression.cpp.o): undefined symbol: inflateInit2_
wasm-ld: error: E:/libs/assimp-5.2.5/build/lib\libassimp.a(unzip.c.o): undefined symbol: get_crc_table
wasm-ld: error: E:/libs/assimp-5.2.5/build/lib\libassimp.a(unzip.c.o): undefined symbol: crc32
wasm-ld: error: E:/libs/assimp-5.2.5/build/lib\libassimp.a(Compression.cpp.o): undefined symbol: inflate
wasm-ld: error: E:/libs/assimp-5.2.5/build/lib\libassimp.a(unzip.c.o): undefined symbol: crc32
em++: error: 'C:/emsdk/upstream/bin\wasm-ld.exe -o .\load-with-assimp-wasm-opengl2-qt6-cpp.wasm C:/Qt/6.7.0/wasm_singlethread/lib/libQt6BundledFreetype.a C:/Qt/6.7.0/wasm_singlethread/lib/libQt6BundledLibpng.a main.obj load-with-assimp-wasm-opengl2-qt6-cpp.js_plugin_import.obj -LE:/libs/assimp-5.2.5/build/lib E:/libs/assimp-5.2.5/build/lib\libassimp.a C:/Qt/6.7.0/wasm_singlethread/lib/objects-Release/QWasmIntegrationPlugin_resources_1/.rcc/qrc_wasmfonts_init.cpp.o C:/Qt/6.7.0/wasm_singlethread/lib/objects-Release/QWasmIntegrationPlugin_resources_2/.rcc/qrc_wasmwindow_init.cpp.o C:/Qt/6.7.0/wasm_singlethread/lib/objects-Release/Gui_resources_1/.rcc/qrc_qpdf_init.cpp.o C:/Qt/6.7.0/wasm_singlethread/lib/objects-Release/Gui_resources_2/.rcc/qrc_gui_shaders_init.cpp.o C:/Qt/6.7.0/wasm_singlethread/plugins/platforms/libqwasm.a C:/Qt/6.7.0/wasm_singlethread/plugins/iconengines/libqsvgicon.a C:/Qt/6.7.0/wasm_singlethread/plugins/imageformats/libqgif.a C:/Qt/6.7.0/wasm_singlethread/plugins/imageformats/libqico.a C:/Qt/6.7.0/wasm_singlethread/plugins/imageformats/libqjpeg.a C:/Qt/6.7.0/wasm_singlethread/lib/libQt6BundledLibjpeg.a C:/Qt/6.7.0/wasm_singlethread/plugins/imageformats/libqsvg.a C:/Qt/6.7.0/wasm_singlethread/lib/libQt6Svg.a C:/Qt/6.7.0/wasm_singlethread/lib/objects-Release/Widgets_resources_1/.rcc/qrc_qstyle_init.cpp.o C:/Qt/6.7.0/wasm_singlethread/lib/objects-Release/Widgets_resources_2/.rcc/qrc_qstyle1_init.cpp.o C:/Qt/6.7.0/wasm_singlethread/lib/objects-Release/Widgets_resources_3/.rcc/qrc_qstyle_fusion_init.cpp.o C:/Qt/6.7.0/wasm_singlethread/lib/objects-Release/Widgets_resources_4/.rcc/qrc_qmessagebox_init.cpp.o C:/Qt/6.7.0/wasm_singlethread/lib/libQt6OpenGLWidgets.a C:/Qt/6.7.0/wasm_singlethread/lib/libQt6OpenGL.a C:/Qt/6.7.0/wasm_singlethread/lib/libQt6Widgets.a C:/Qt/6.7.0/wasm_singlethread/lib/libQt6Gui.a C:/Qt/6.7.0/wasm_singlethread/lib/libQt6BundledHarfbuzz.a C:/Qt/6.7.0/wasm_singlethread/lib/libQt6BundledFreetype.a C:/Qt/6.7.0/wasm_singlethread/lib/libQt6BundledLibpng.a C:/Qt/6.7.0/wasm_singlethread/lib/libQt6Core.a C:/Qt/6.7.0/wasm_singlethread/lib/libQt6BundledZLIB.a C:/Qt/6.7.0/wasm_singlethread/lib/libQt6BundledPcre2.a -LC:\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten --whole-archive -lfetch -lembind-rtti --no-whole-archive -lGL-webgl2 -lal -lhtml5 -lstubs-debug -lnoexit -lc-debug -ldlmalloc -lcompiler_rt -lc++-noexcept -lc++abi-debug-noexcept -lsockets -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr C:\Users\8OBSER~1\AppData\Local\Temp\tmpl78yuxdvlibemscripten_js_symbols.so --export-if-defined=main --export-if-defined=__start_em_asm --export-if-defined=__stop_em_asm --export-if-defined=__start_em_lib_deps --export-if-defined=__stop_em_lib_deps --export-if-defined=__start_em_js --export-if-defined=__stop_em_js --export-if-defined=__main_argc_argv --export-if-defined=fflush --export=emscripten_stack_get_end --export=emscripten_stack_get_free --export=emscripten_stack_get_base --export=emscripten_stack_get_current --export=emscripten_stack_init --export=__cxa_demangle --export=stackSave --export=stackRestore --export=stackAlloc --export=__errno_location --export=malloc --export=free --export=__wasm_call_ctors --export-table -z stack-size=5242880 --initial-memory=52428800 --no-entry --max-memory=2147483648 --stack-first' failed (returned 1)
mingw32-make: *** [Makefile:69: .\load-with-assimp-wasm-opengl2-qt6-cpp.js] Error 1
15:56:50: The process "C:\Qt\Tools\mingw1120_64\bin\mingw32-make.exe" exited with code 2.
Error while building/deploying project load-with-assimp-wasm-opengl2-qt6-cpp (kit: WebAssembly Qt 6.7.0 (single-threaded))
When executing step "Make"
15:56:50: Elapsed time: 00:16.

load-with-assimp-wasm-opengles2-qt6-cpp.pro

QT += core gui openglwidgets widgets

win32: LIBS += -lopengl32

INCLUDEPATH += "E:/libs/assimp-5.2.5/include"
LIBS += -L"E:/libs/assimp-5.2.5/build/lib"
LIBS += -lassimp

CONFIG += c++11

# You can make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
# disables all the APIs deprecated before Qt 6.0.0
DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000

SOURCES += \
    main.cpp

main.cpp

#include <QtCore/QDebug>
#include <QtGui/QMatrix4x4>
#include <QtGui/QVector3D>
#include <QtGui/QOpenGLFunctions>
#include <QtOpenGL/QOpenGLBuffer>
#include <QtOpenGL/QOpenGLShaderProgram>
#include <QtOpenGLWidgets/QOpenGLWidget>
#include <QtWidgets/QApplication>
#include <QtWidgets/QMessageBox>

#include <assimp/Importer.hpp>
#include <assimp/postprocess.h>
#include <assimp/scene.h>

class OpenGLWidget : public QOpenGLWidget, private QOpenGLFunctions
{
public:
    OpenGLWidget()
    {
        setWindowTitle("Qt C++, OpenGL");
        resize(400, 400);
    }

private:
    QOpenGLBuffer m_vertPosBuffer;
    QOpenGLShaderProgram m_program;
    int m_numVertices;
    QMatrix4x4 m_modelMatrix;

    void initializeGL() override
    {
        initializeOpenGLFunctions();
        glClearColor(0.1f, 0.1f, 0.1f, 1.f);
        glEnable(GL_DEPTH_TEST);

        Assimp::Importer importer;
        const char *path = "assets/models/plane-blender.dae";
        const aiScene *scene = importer.ReadFile(path, aiProcess_Triangulate | aiProcess_FlipUVs);
        if (!scene || scene->mFlags & AI_SCENE_FLAGS_INCOMPLETE || !scene->mRootNode)
        {
            qDebug() << "Assimp Error:" << importer.GetErrorString();
            QMessageBox::critical(this, "Assimp Error:", importer.GetErrorString());
            return;
        }

        m_numVertices = scene->mMeshes[0]->mNumVertices;
        float vertPositions[m_numVertices * 3];
        int vertPosIndex = 0;
        for (int i = 0; i < m_numVertices; i++)
        {
            vertPositions[vertPosIndex++] = scene->mMeshes[0]->mVertices[i].x;
            vertPositions[vertPosIndex++] = scene->mMeshes[0]->mVertices[i].y;
            vertPositions[vertPosIndex++] = scene->mMeshes[0]->mVertices[i].z;
           // qDebug() << scene->mMeshes[0]->mVertices[i].x << ", "
           //          << scene->mMeshes[0]->mVertices[i].y << ", "
           //           << scene->mMeshes[0]->mVertices[i].z;
           //  qDebug() << "\n";
        }
        m_vertPosBuffer.create();
        m_vertPosBuffer.bind();
        m_vertPosBuffer.allocate(vertPositions, sizeof(vertPositions));

        const char *vertShaderSrc =
            "attribute vec3 aPosition;"
            "uniform mat4 uModelMatrix;"
            "void main()"
            "{"
            "    gl_Position = uModelMatrix * vec4(aPosition, 1.0);"
            "}";
        const char *fragShaderSrc =
            "void main()"
            "{"
            "    gl_FragColor = vec4(0.5, 0.2, 0.7, 1.0);"
            "}";
        m_program.create();
        m_program.addShaderFromSourceCode(QOpenGLShader::ShaderTypeBit::Vertex,
            vertShaderSrc);
        m_program.addShaderFromSourceCode(QOpenGLShader::ShaderTypeBit::Fragment,
            fragShaderSrc);
        m_program.link();
    }

    void resizeGL(int w, int h) override
    {
        glViewport(0, 0, w, h);
    }

    void paintGL() override
    {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        m_modelMatrix.setToIdentity();
        m_modelMatrix.scale(0.5);
        m_program.bind();
        m_program.setUniformValue("uModelMatrix", m_modelMatrix);
        m_vertPosBuffer.bind();
        m_program.setAttributeBuffer("aPosition", GL_FLOAT, 0, 3);
        m_program.enableAttributeArray("aPosition");
        glDrawArrays(GL_TRIANGLES, 0, m_numVertices);
    }
};

int main(int argc, char *argv[])
{
    QApplication::setAttribute(Qt::ApplicationAttribute::AA_UseDesktopOpenGL);
    QApplication app(argc, argv);
    OpenGLWidget w;
    w.show();
    return app.exec();
}

[8Observer8]

I created the same topics on Qt Forum: https://forum.qt.io/topic/155591/how-to-set-up-assimp-for-qt6-mingw-64-bit and Stack Overflow: https://stackoverflow.com/questions/78230555/how-to-set-up-assimp-for-qt6-mingw-64-bit-to-run-on-webassembly

[8Observer8]

I built zlib with these commands:

> cd zlib-1.3.1 && mkdir build && cd build
> emcmake cmake ..
> emmake make

libz.a (245 KB) was generated.

I set up it like this:

LIBS += -L"E:\libs\zlib-1.3.1\lib"
LIBS += -lz

Now it compiles. But I think Assimp must include zlib. A size of libassimp.a is 89.3 MB.

I have this error now:

I had a problem with loading models from Qt Resources with Assimp: Loading a 3D model from Qt Resources. Assimp Error: No suitable reader found for the file format of file I decided do not use Qt Resources to solve that problem. But now I don't know how to solve it for WASM.

[8Observer8]

Botje wrote the next comment on Stack Overflow:

libassimp.a does not contain zlib. If you inspect the makefile generated by cmake you will see it just collects all the object files and does not add libz in any way. That is reserved for the final step where your application links to libassimp.a, because other dependencies might also need zlib and if each brings its own copy you get conflicts.