This commit fixes the bug that the bgfx does not respect the `devicePixelRatio` parameter passed to nanovg's `nvgBeginFrame()` function. The problem is caused by the `bgfx::setViewRect()` call defined in the `nvgRenderViewport()` function, as it should take size in consideration of the `devicePixelRatio` value.
However, this commit does not fix nanovg's example app because currently there is no easy way to pass the scale value to the `ExampleNanoVG::update()` method as it calls `nvgBeginFrame()`.
This commit moves the additional nanovg functions for bgfx to a separate header file, so it is possible to compile the original nanovg source files with bgfx in a custom build environment.
Change vs_ibl_skybox.sc to correctly use radians instead of degrees when
specifying field-of-view. Additionally, use u_viewRect to find the correct
aspect ratio of the viewport, instead of hard-coding to 4/3.
Change fs_ibl_skybox.sc, fixing a number of small issues and mistakes. These
mistakes would lead to incorrect lighting results, especially with metallic
materials at glancing angles.
This commit does not include the rebuilt .bin output of shaderc for these
shaders.
On Android when the application goes into the background, the EGL
window surface becomes invalid. It is possible to resume rendering when
coming to the foreground by resetting and reinitializing bgfx from
scratch, but this is costly in terms of performance.
This patch provides an alternative by letting the application provide a
new native window, causing bgfx to recreate just the EGL window surface
while keeping the EGL context intact. This allows the application to
resume rendering without needing to reload textures, shaders, etc.
To test, build and run the Hello World example on Android, switch to
another app and then back again. The screen should not remain blank
after switching back.
