The problem is that textures with float internal formats can be used in framebuffers only when some extensions are available. This is a basic functionality and we need something that is supported on all drivers. As far as I tested, the basic integer GL_RGBA8 format works fine.
Another problem is with GL_BGRA format. The extension with GL_BGRA support is available for almost every device and irrlicht is able to load all textures from files (it has a fallback mode anyway), but when it's used as a texture for framebuffer, it produces a black screen. Again it works fine with GL_RGBA format.
The only issue that is not fixed is SSAO rendering. It uses linear depth rtt, which has GL_R32F type and which can't be easily changed to something other. I disabled SSAO for now, because it is too slow for embedded devices anyway.
I didn't change anything in original OpenGL 3.x rendering, so everything should work as before.
On desktop medium and high precision is generally the same, at least for mesa drivers. But on some Android devices medium precision is much worse, which causes artifacts. We need high precision float variables in vertex shaders for proper scene rendering. Setting different precision for fragment and vertex shaders seems to be not possible, so we just set it to high for both shader types when it's available.
The GL_CONDITION_SATISFIED says that the sync was signaled before the timeout expired. In this case there is no reason to make another glClientWaitSync execution.
Our vidmode code is old, has some bugs (eg. resolution is not restored properly in some cases), doesn't have multi monitor support and IMO shouldn't be used in current state.
If someone really wants to use it, the flags can be set directly in IrrCompileConfig.h.
It allows to increase performance on devices that have only one available resolution.
It also allows to draw GUI elements in full resolution while rendering the scene with slightly lower resolution, which gives you few additional FPS.
Note that particles don't work as expected yet with this feature.
