Skip to content

README-android.md

Latest commit

 

History

History
98 lines (61 loc) · 3.42 KB

README-android.md

File metadata and controls

98 lines (61 loc) · 3.42 KB

Android README

Hello everyone, I'm going to write here a few difficulties that I encountered when I ported my game engine to Android:

  1. SDL_GetBasePath() doesn't return anything on android, so you should use and empty string as the base path (""), NOT "./" as in the docs Example: to access assets/texture.png, just pass the string "assets/texture.png" to SDL IO.

  2. All the direct filesystem calls have to go: <filesystem> doesn't work on Android and produces cryptic false-positive runtime exceptions.

Stuff like stbi_load should be replaced with a combination of SDL_LoadFile which loades the file to memory and stbi_load_from_memory which reads from the memory.

For assimp you need to compile it yourself (see README.md). You do NOT need ASSIMP_ANDROID_JNIIOSYSTEM. It won't work, trust me.

Link it by specifing the directory of your compiled assimp in CMakeLists.txt

Dynamic link it, don't worry

For assimp you also need custom IOs, see src/managers/assimpIO.cpp

SDL_GetPathInfo doesn't work on android, so you must test the file by trying to make a IO stream with it, slow but no other method

  1. Android rotation should not be specified in androidmanifest.xml, it won't work. Instead set the hint:
SDL_SetHint(SDL_HINT_ORIENTATIONS, "LandscapeLeft LandscapeRight");

Also to hide the top bar, just set the window to fullscreen

  1. The assets shall go to android/app/src/main/assets, it get's packed automatically

  2. OpenGL glPolygonMode isn't present in OpenGL ES, Remove it

  3. When looking at SDL examples, look at opengles2 the 2 is important. Same when setting the driver hint.

  4. Use glad's gladLoadGLES2Loader to load opengl funcs

  5. Don't forget to replace the version string when compiling shaders. ImGui too.

  6. Android NDK's stdc++ is horribly outdated, stuff like <ranges> and string.contains() should be used behind feature tests.

Here is a patch to make Eigen work

@@ -1306,14 +1306,14 @@ inline int queryTopLevelCacheSize() {
 * This wraps C++20's std::construct_at, using placement new instead if it is not available.
 */

#if EIGEN_COMP_CXXVER >= 20
using std::construct_at;
#else
// #if EIGEN_COMP_CXXVER >= 20
// using std::construct_at;
// #else
template <class T, class... Args>
EIGEN_DEVICE_FUNC T* construct_at(T* p, Args&&... args) {
  return ::new (const_cast<void*>(static_cast<const volatile void*>(p))) T(std::forward<Args>(args)...);
}
#endif
// #endif

/** \internal
 * This wraps C++17's std::destroy_at.  If it's not available it calls the destructor.

10: Here is the order for initializing OpenGL:

1. Set SDL Hints

2. Init SDL

3. Set GL atrributes

4. Make window

5. Make context

6. Load GL with glad

7. Make context current

8. Print gl info
  1. Don't forget to change context flags:
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);

  1. Android needs java 17, and can only use 17. While compiling assimp add the API level 24 flag.

  2. When using SDL android projects, just delete all the android.mk

  3. Uncaught RuntimeError: indirect call to null is probably just a undefined opengl function in Emscripten

  4. When compiling for web, you need to add flags: -sMIN_WEBGL_VERSION=2 -sMAX_WEBGL_VERSION=2 -sFULL_ES2 -sFULL_ES3 -sALLOW_MEMORY_GROWTH or your app will break.