I want to make CMake and Emscripten friends. Didn't find more or less informative documentation on the Emscripten project website, but they provide CMake toolchain file so I think it should be possible.
So far very basic compilation without advanced parameters works fine, but I have issues while using embind
and preloading files.
warning: unresolved symbol: _embind_register_class
which results in respective errors while loading compiled JS file in rowser..data
file is generated during the compilation.I've created a minimalistic example which includes two targets: one "normal" (client) and one manual (manual-client) which simply runs emcc as I expect it to be run: https://github.com/xwaffelx/minimal-cmake-emscripten-project/blob/master/README.md
Although manual way works, I don't think it is a proper way to do it...
--- Update ---
As requested, here is even more short example:
cmake_minimum_required(VERSION 2.8)
cmake_policy(SET CMP0015 NEW)
project(emtest)
set(CMAKE_VERBOSE_MAKEFILE on)
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/build.emscripten)
include_directories("lib/assimp/include")
link_directories("lib/assimp/lib-js")
link_libraries("assimp")
file(GLOB_RECURSE CORE_HDR src/.h)
file(GLOB_RECURSE CORE_SRC src/.cpp)
add_definitions("-s DEMANGLE_SUPPORT=1 --preload-file ${CMAKE_SOURCE_DIR}/assets --bind")
add_executable(client ${CORE_SRC} ${CORE_HDR})
Result should be equivalent to running the following command manualy:
emcc
-Ilib/assimp/include
-s DEMANGLE_SUPPORT=1
--preload-file assets
--bind
Application.cpp
lib/assimp/lib-js/libassimp.so
-o client.js
Here is the Application.cpp:
#include "Application.h"
#include <iostream>
#include <assimp/Importer.hpp>
#include <assimp/scene.h>
#include <assimp/postprocess.h>
void Application::Initialize() {
std::cout << "Initializing application." << std::endl;
Assimp::Importer importer; // For test purpose
}
void Application::SayHello() {
std::cout << "Hello!" << std::endl;
}
and Application.h:
#ifndef APPLICATION_H
#define APPLICATION_H
#include <emscripten/html5.h>
#include <emscripten/bind.h>
namespace e = emscripten;
class Application {
public:
void Initialize();
void SayHello();
};
EMSCRIPTEN_BINDINGS(EMTest) {
e::class_<Application>("Application")
.constructor()
.function("Initialize", &Application::Initialize)
.function("SayHello", &Application::SayHello);
}
#endif
THen I run cmake as follows:
cmake -DCMAKE_TOOLCHAIN_PATH=path/to/Emscripten.cmake .. && make
However, warnings like warning: unresolved symbol: _embind_register_class
are produced during linking and running the code and no preloaded data in client.data
file is created while compiling CMake project. At the same time no warnings and everything runs OK while compiling manually.
To build using Emscripten you need to replace gcc with emcc in your makefiles. This is done using emconfigure, which sets the appropriate environment variables like CXX (C++ compiler) and CC (the compiler).
emcmake is a helper for cmake, setting various environment. variables so that emcc etc.
asm. js is superseded by WebAssembly.
The solution was to specify all the flags during the linking by providing following CMake instruction:
set_target_properties(client PROPERTIES LINK_FLAGS "-s DEMANGLE_SUPPORT=1 --preload-file assets --bind")
Thanks to developers of emscripten who helped in the github issues tracker.
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