It needs to use Bool (which is an int) and not BOOL (which is CARD8), which
causes problems on platforms with different byte order and alignment, etc.
Fixes Bugzilla #4326.
On Mojave, this will report large numbers for retina displays in fullscreen
mode, which isn't how it works on previous versions.
(transplanted from c6c1731780e2bef94f944a4795e2dfbba46d9500)
I have no idea if this works (or if it ever worked, having now examined this
code), as I have no way to compile or test this.
If it's broken, send patches. :)
This means it doesn't have to block while the current frame finishes using the
vertex buffer; it just moves on to the next, probably-not-in-use buffer.
- high-level filters out duplicate render commands from the queue so
backends don't have to.
- Setting draw color is now a render command, so backends can put color
information into the vertex buffer to upload with everything else instead
of setting it with slower dynamic data later.
- backends can request that they always batch, even for legacy programs,
since the lowlevel API can deal with it (Metal, and eventually Vulkan
and such...)
- high-level makes sure the queue has at least one setdrawcolor and
setviewport command before any draw calls, so the backends don't ever have
to manage cases where this hasn't been explicitly set yet.
- backends allocating vertex buffer space can specify alignment, and the
high-level will keep track of gaps in the buffer between the last used
positions and the aligned data that can be used for later allocations
(Metal and such need to specify some constant data on 256 byte boundaries,
but we don't want to waste all that space we had to skip to meet alignment
requirements).
It now uses a growable linked list that keeps a pool of allocated items for
reuse, and reallocs the vertex array as necessary. Testsprite2 can scale to
20,000 (or more!) draws now without drama.
This moves all the rendering to a command list that is flushed to the GL as
necessary, making most common activities upload a single vertex buffer per
frame and dramatically reducing state changes. In pathological cases,
like Emscripten running on iOS's Safari, performance can go from a dozen
draw calls killing your performance to 1000 draw calls running smoothly.
This is work in progress, and not ready to ship. Among other things, it has
a hardcoded array that isn't checked for overflow. But the basic idea is
sound!
