Only sync WebVR framedata with compositor when GetFrameData function is called inside a VRDisplay.requestAnimationFrame callback.

This commit is contained in:
Imanol Fernandez 2017-03-22 17:27:07 +01:00
parent cea1760eb7
commit 134e918aae

View file

@ -71,6 +71,7 @@ pub struct VRDisplay {
frame_data_status: Cell<VRFrameDataStatus>,
#[ignore_heap_size_of = "channels are hard"]
frame_data_receiver: DOMRefCell<Option<IpcReceiver<Result<Vec<u8>, ()>>>>,
running_display_raf: Cell<bool>
}
unsafe_no_jsmanaged_fields!(WebVRDisplayData);
@ -110,6 +111,7 @@ impl VRDisplay {
raf_callback_list: DOMRefCell::new(vec![]),
frame_data_status: Cell::new(VRFrameDataStatus::Waiting),
frame_data_receiver: DOMRefCell::new(None),
running_display_raf: Cell::new(false),
}
}
@ -169,8 +171,13 @@ impl VRDisplayMethods for VRDisplay {
// https://w3c.github.io/webvr/#dom-vrdisplay-getframedata-framedata-framedata
fn GetFrameData(&self, frameData: &VRFrameData) -> bool {
// If presenting we use a synced data with compositor for the whole frame
if self.presenting.get() {
// If presenting we use a synced data with compositor for the whole frame.
// Frame data is only synced with compositor when GetFrameData is called from
// inside the VRDisplay.requestAnimationFrame. This is checked using the running_display_raf property.
// This check avoids data race conditions when calling GetFrameData from outside of the
// VRDisplay.requestAnimationFrame callbacks and fixes a possible deadlock during the interval
// when the requestAnimationFrame is moved from window to VRDisplay.
if self.presenting.get() && self.running_display_raf.get() {
if self.frame_data_status.get() == VRFrameDataStatus::Waiting {
self.sync_frame_data();
}
@ -525,6 +532,7 @@ impl VRDisplay {
fn handle_raf(&self, end_sender: &mpsc::Sender<Result<(f64, f64), ()>>) {
self.frame_data_status.set(VRFrameDataStatus::Waiting);
self.running_display_raf.set(true);
let mut callbacks = mem::replace(&mut *self.raf_callback_list.borrow_mut(), vec![]);
let now = self.global().as_window().Performance().Now();
@ -536,6 +544,7 @@ impl VRDisplay {
}
}
self.running_display_raf.set(false);
if self.frame_data_status.get() == VRFrameDataStatus::Waiting {
// User didn't call getFrameData while presenting.
// We automatically reads the pending VRFrameData to avoid overflowing the IPC-Channel buffers.