It is an error to use a gl.Context concurrently. (Each Context
contains a state machine, so there is no way this can work.)
Up until now only the GL driver could report such a misuse, and
it generally does a poor job of it. Our command buffer adds some
small oppertunity for the race detector to help, but it makes it
harder to debug other kinds of driver crashes, so it is worth
disabling in debug mode.
To make it easy, compiling with -tags gldebug now inserts an
explicit check that there are no other active GL calls outstanding.
Adding something like:
go func() {
for {
glctx.GetInteger(gl.ALPHA_BITS)
}
}()
to x/mobile/example/basic now reliably crashes when compiled
with -tags gldebug, providing a stack trace that includes both
misbehaving goroutines.
Change-Id: I3d85d94220bca2a15eaf2742f13b44db1f3428bf
Reviewed-on: https://go-review.googlesource.com/15180
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
All OpenGL functions are now methods on a Context interface. The
gl.Context matches the one loaded into thread-local storage in C.
For mobile apps, the context is owned by an app.App. For now, it is
provided through the events channel on a lifecycle event. Long-term,
it should probably be available by a method on app.App, but this is
inherently racey with our current use of a channel to deliver events.
Shiny-based programs will have a gl.Context associated with a each
shiny.Window. The expectation is each Window will have different
contexts, allowing them to draw separately.
Change-Id: Ie09986fb74e493129f2ea542a151c95c6fa29812
Reviewed-on: https://go-review.googlesource.com/13431
Reviewed-by: Nigel Tao <nigeltao@golang.org>
This change will break Darwin. I have only built and tested this on
desktop linux and Android linux. A follow-up CL will fix Darwin.
Currently, OpenGL gets its own thread, and UI C code (e.g. the Android
event loop, or the X11 event loop) gets its own thread. This relies on
multiple system-provided UI-related C libraries working nicely together,
even when running on different threads. Keeping all the C code on the
one thread seems more sound.
As side-effects:
- In package app/debug, DrawFPS now takes an explicit Config.
- In package app, some callbacks now take an explicit Config.
- In package exp/sprite, Render now takes an explicit Config.
- In package event, there are new events (Config, Draw, Lifecycle),
and an event filter mechanism to replace multiple app Callbacks.
- In package geom, the deprecated Width, Height and PixelsPerPt global
variables were removed in favor of an event.Config that is
explicitly passed around (and does not require mutex-locking).
Converting a geom.Pt to pixels now requires passing a pixelsPerPt.
- In package gl, the Do, Start and Stop functions are removed, as well
as the need to call Start in its own goroutine. There is no longer a
separate GL thread. Instead, package app explicitly performs any GL
work (gl.DoWork) when some is available (gl.WorkAvailable).
- In package gl/glutil, Image.Draw now takes an explicit Config.
Callbacks are no longer executed on 'the UI thread'.
Changing the app programming model from callbacks to events (since a
channel of events works with select) will be a follow-up change.
Change-Id: Id9865cd9ee1c45a98c613e9021a63c17226a64b1
Reviewed-on: https://go-review.googlesource.com/11351
Reviewed-by: David Crawshaw <crawshaw@golang.org>
All GL function calls fill out a C.struct_fnargs and drop it on the
work queue. The Start function drains the work queue and hands
over a batch of calls to C.process which runs them. This allows
multiple GL calls to be executed in a single cgo call.
A GL call is marked as blocking if it returns a value, or if it
takes a Go pointer. In this case the call will not return until
C.process sends a value on the retvalue channel.
Change-Id: I4c76b2a8ad55f57b0c98d200d0fb708d4634e042
Reviewed-on: https://go-review.googlesource.com/10452
Reviewed-by: Nigel Tao <nigeltao@golang.org>
