Some hardware supports ARB_compute_shader but not 4.3, causing
shader compilation failures because currently we switch to GLSL 430
if compute shaders are detected.
Instead, just detect GL 4.3 instead of looking for the compute shader
extension. This means that compute shaders will sometimes be
unavailable even when they're supported.
It would be possible to improve this by modifying the way shaders
are compiled. Maybe the highest supported GLSL version should be used,
but this makes shader authoring somewhat more difficult.
We never try to do this anyway, and the unmapping code in discard
doesn't flush contents so it's better for people to unmap the
buffer themselves before calling discard.
It appears that GL_MAP_UNSYNCHRONIZED_BIT interferes with
GL_MAP_INVALIDATE_BUFFER_BIT's ability to discard buffer
contents. Removing the unsynchronized bit fixes visual
glitches on Intel HD GPUs.
There are two HOME keys defined in keycodes.h, the previously used
doesn't work and is labeled with the following comment: "This key
is handled by the framework and is never delivered to applications."
A little more declarative, less duplication.
Misc changes:
- Added link time optimization
- Added -Os to link stage
- Use separate Android SDK and NDK paths
OpenXR basically has a hard requirement that a graphics API is available
before its session can be created. Currently the graphics module isn't
always around when headset initialization takes place. Polling the
graphics availability in update/renderTo has some consequences for calls
made to the headset module in lovr.load or during the first few frames.
So instead we're going to delay headset initialization to a special
function that is called after modules are required. It can also be
called manually if the window creation is delayed.