VR: Initial Virtual Reality support - Milestone 1, Scene Inspection

NOTE: While most of the milestone 1 goals are there, a few smaller features and
improvements are still to be done.

Big picture of this milestone: Initial, OpenXR-based virtual reality support
for users and foundation for advanced use cases.
Maniphest Task: https://developer.blender.org/T71347
The tasks contains more information about this milestone.

To be clear: This is not a feature rich VR implementation, it's focused on the
initial scene inspection use case. We intentionally focused on that, further
features like controller support are part of the next milestone.

- How to use?
Instructions on how to use this are here:
https://wiki.blender.org/wiki/User:Severin/GSoC-2019/How_to_Test
These will be updated and moved to a more official place (likely the manual) soon.

Currently Windows Mixed Reality and Oculus devices are usable. Valve/HTC
headsets don't support the OpenXR standard yet and hence, do not work with this
implementation.

---------------

This is the C-side implementation of the features added for initial VR
support as per milestone 1. A "VR Scene Inspection" Add-on will be
committed separately, to expose the VR functionality in the UI. It also
adds some further features for milestone 1, namely a landmarking system
(stored view locations in the VR space)

Main additions/features:
* Support for rendering viewports to an HMD, with good performance.
* Option to sync the VR view perspective with a fully interactive,
  regular 3D View (VR-Mirror).
* Option to disable positional tracking. Keeps the current position (calculated
  based on the VR eye center pose) when enabled while a VR session is running.
* Some regular viewport settings for the VR view
* RNA/Python-API to query and set VR session state information.
* WM-XR: Layer tying Ghost-XR to the Blender specific APIs/data
* wmSurface API: drawable, non-window container (manages Ghost-OpenGL and GPU
  context)
* DNA/RNA for management of VR session settings
* `--debug-xr` and `--debug-xr-time` commandline options
* Utility batch & config file for using the Oculus runtime on Windows.
* Most VR data is runtime only. The exception is user settings which are saved
  to files (`XrSessionSettings`).
* VR support can be disabled through the `WITH_XR_OPENXR` compiler flag.

For architecture and code documentation, see
https://wiki.blender.org/wiki/Source/Interface/XR.

---------------

A few thank you's:
* A huge shoutout to Ray Molenkamp for his help during the project - it would
  have not been that successful without him!
* Sebastian Koenig and Simeon Conzendorf for testing and feedback!
* The reviewers, especially Brecht Van Lommel!
* Dalai Felinto for pushing and managing me to get this done ;)
* The OpenXR working group for providing an open standard. I think we're the
  first bigger application to adopt OpenXR. Congratulations to them and
  ourselves :)

This project started as a Google Summer of Code 2019 project - "Core Support of
Virtual Reality Headsets through OpenXR" (see
https://wiki.blender.org/wiki/User:Severin/GSoC-2019/).
Some further information, including ideas for further improvements can be found
in the final GSoC report:
https://wiki.blender.org/wiki/User:Severin/GSoC-2019/Final_Report

Differential Revisions: D6193, D7098

Reviewed by: Brecht Van Lommel, Jeroen Bakker

1 files changed, 10 insertions, 10 deletions

diff --git a/source/blender/editors/space_view3d/view3d_utils.c b/source/blender/editors/space_view3d/view3d_utils.c
index bad283740c8..55778db7353 100644
--- a/source/blender/editors/space_view3d/view3d_utils.c
+++ b/source/blender/editors/space_view3d/view3d_utils.c
@@ -459,7 +459,7 @@ bool ED_view3d_persp_ensure(const Depsgraph *depsgraph, View3D *v3d, ARegion *re
   RegionView3D *rv3d = region->regiondata;
   const bool autopersp = (U.uiflag & USER_AUTOPERSP) != 0;
 
-  BLI_assert((rv3d->viewlock & RV3D_LOCKED) == 0);
+  BLI_assert((RV3D_LOCK_FLAGS(rv3d) & RV3D_LOCK_ANY_TRANSFORM) == 0);
 
   if (ED_view3d_camera_lock_check(v3d, rv3d)) {
     return false;
@@ -679,7 +679,7 @@ static void view3d_boxview_clip(ScrArea *sa)
     if (region->regiontype == RGN_TYPE_WINDOW) {
       RegionView3D *rv3d = region->regiondata;
 
-      if (rv3d->viewlock & RV3D_BOXCLIP) {
+      if (RV3D_LOCK_FLAGS(rv3d) & RV3D_BOXCLIP) {
         if (ELEM(rv3d->view, RV3D_VIEW_TOP, RV3D_VIEW_BOTTOM)) {
           if (region->winx > region->winy) {
             x1 = rv3d->dist;
@@ -751,7 +751,7 @@ static void view3d_boxview_clip(ScrArea *sa)
     if (region->regiontype == RGN_TYPE_WINDOW) {
       RegionView3D *rv3d = region->regiondata;
 
-      if (rv3d->viewlock & RV3D_BOXCLIP) {
+      if (RV3D_LOCK_FLAGS(rv3d) & RV3D_BOXCLIP) {
         rv3d->rflag |= RV3D_CLIPPING;
         memcpy(rv3d->clip, clip, sizeof(clip));
         if (rv3d->clipbb) {
@@ -822,10 +822,10 @@ void view3d_boxview_sync(ScrArea *sa, ARegion *region)
     if (artest != region && artest->regiontype == RGN_TYPE_WINDOW) {
       RegionView3D *rv3dtest = artest->regiondata;
 
-      if (rv3dtest->viewlock & RV3D_LOCKED) {
+      if (RV3D_LOCK_FLAGS(rv3dtest) & RV3D_LOCK_ROTATION) {
         rv3dtest->dist = rv3d->dist;
         view3d_boxview_sync_axis(rv3dtest, rv3d);
-        clip |= rv3dtest->viewlock & RV3D_BOXCLIP;
+        clip |= RV3D_LOCK_FLAGS(rv3dtest) & RV3D_BOXCLIP;
 
         ED_region_tag_redraw(artest);
       }
@@ -848,12 +848,12 @@ void view3d_boxview_copy(ScrArea *sa, ARegion *region)
     if (artest != region && artest->regiontype == RGN_TYPE_WINDOW) {
       RegionView3D *rv3dtest = artest->regiondata;
 
-      if (rv3dtest->viewlock) {
+      if (RV3D_LOCK_FLAGS(rv3dtest)) {
         rv3dtest->dist = rv3d->dist;
         copy_v3_v3(rv3dtest->ofs, rv3d->ofs);
         ED_region_tag_redraw(artest);
 
-        clip |= ((rv3dtest->viewlock & RV3D_BOXCLIP) != 0);
+        clip |= ((RV3D_LOCK_FLAGS(rv3dtest) & RV3D_BOXCLIP) != 0);
       }
     }
   }
@@ -874,7 +874,7 @@ void ED_view3d_quadview_update(ScrArea *sa, ARegion *region, bool do_clip)
    * properties are always being edited, weak */
   viewlock = rv3d->viewlock;
 
-  if ((viewlock & RV3D_LOCKED) == 0) {
+  if ((viewlock & RV3D_LOCK_ROTATION) == 0) {
     do_clip = (viewlock & RV3D_BOXCLIP) != 0;
     viewlock = 0;
   }
@@ -899,12 +899,12 @@ void ED_view3d_quadview_update(ScrArea *sa, ARegion *region, bool do_clip)
     }
   }
 
-  if (rv3d->viewlock & RV3D_BOXVIEW) {
+  if (RV3D_LOCK_FLAGS(rv3d) & RV3D_BOXVIEW) {
     view3d_boxview_sync(sa, ar_sync ? ar_sync : sa->regionbase.last);
   }
 
   /* ensure locked regions have an axis, locked user views don't make much sense */
-  if (viewlock & RV3D_LOCKED) {
+  if (viewlock & RV3D_LOCK_ROTATION) {
     int index_qsplit = 0;
     for (region = sa->regionbase.first; region; region = region->next) {
       if (region->alignment == RGN_ALIGN_QSPLIT) {