XR Controller Support Step 4: Controller Drawing

Addresses T77127 (Controller Drawing).

Adds VR controller visualization and custom drawing via draw
handlers. Add-ons can draw to the XR surface (headset display) and
mirror window by adding a View3D draw handler of region type 'XR' and
draw type 'POST_VIEW'.  Controller drawing and custom overlays can be
toggled individually as XR session options, which will be added in a
future update to the VR Scene Inspection add-on.

For the actual drawing, the OpenXR XR_MSFT_controller_model extension
is used to load a glTF model provided by the XR runtime. The model's
vertex data is then used to create a GPUBatch in the XR session
state. Finally, this batch is drawn via the XR surface draw handler
mentioned above.

For runtimes that do not support the controller model extension, a
a simple fallback shape (sphere) is drawn instead.

Reviewed By: Severin, fclem

Differential Revision: https://developer.blender.org/D10948

4 files changed, 20 insertions, 2 deletions

diff --git a/source/blender/makesdna/DNA_screen_types.h b/source/blender/makesdna/DNA_screen_types.h
index f557890e3e8..86fd6b9744a 100644
--- a/source/blender/makesdna/DNA_screen_types.h
+++ b/source/blender/makesdna/DNA_screen_types.h
@@ -666,8 +666,11 @@ typedef enum eRegion_Type {
   RGN_TYPE_EXECUTE = 10,
   RGN_TYPE_FOOTER = 11,
   RGN_TYPE_TOOL_HEADER = 12,
+  /* Region type used exclusively by internal code and add-ons to register draw callbacks to the XR
+     context (surface, mirror view). Does not represent any real region. */
+  RGN_TYPE_XR = 13,
 
-#define RGN_TYPE_LEN (RGN_TYPE_TOOL_HEADER + 1)
+#define RGN_TYPE_LEN (RGN_TYPE_XR + 1)
 } eRegion_Type;
 
 /* use for function args */
diff --git a/source/blender/makesdna/DNA_view3d_enums.h b/source/blender/makesdna/DNA_view3d_enums.h
index aec52da1bf9..59012a0cd8d 100644
--- a/source/blender/makesdna/DNA_view3d_enums.h
+++ b/source/blender/makesdna/DNA_view3d_enums.h
@@ -30,6 +30,9 @@ typedef enum eV3DOffscreenDrawFlag {
   V3D_OFSDRAW_SHOW_ANNOTATION = (1 << 0),
   V3D_OFSDRAW_OVERRIDE_SCENE_SETTINGS = (1 << 1),
   V3D_OFSDRAW_SHOW_GRIDFLOOR = (1 << 2),
+  V3D_OFSDRAW_SHOW_SELECTION = (1 << 3),
+  V3D_OFSDRAW_XR_SHOW_CONTROLLERS = (1 << 4),
+  V3D_OFSDRAW_XR_SHOW_CUSTOM_OVERLAYS = (1 << 5),
 } eV3DOffscreenDrawFlag;
 
 /** #View3DShading.light */
diff --git a/source/blender/makesdna/DNA_view3d_types.h b/source/blender/makesdna/DNA_view3d_types.h
index 4d88f6f0c15..fafc470b95a 100644
--- a/source/blender/makesdna/DNA_view3d_types.h
+++ b/source/blender/makesdna/DNA_view3d_types.h
@@ -373,6 +373,7 @@ typedef struct View3D {
 #define V3D_HIDE_HELPLINES (1 << 2)
 #define V3D_FLAG_UNUSED_2 (1 << 3) /* cleared */
 #define V3D_XR_SESSION_MIRROR (1 << 4)
+#define V3D_XR_SESSION_SURFACE (1 << 5)
 
 #define V3D_FLAG_UNUSED_10 (1 << 10) /* cleared */
 #define V3D_SELECT_OUTLINE (1 << 11)
@@ -465,6 +466,8 @@ enum {
 #define V3D_FLAG2_UNUSED_13 (1 << 13) /* cleared */
 #define V3D_FLAG2_UNUSED_14 (1 << 14) /* cleared */
 #define V3D_FLAG2_UNUSED_15 (1 << 15) /* cleared */
+#define V3D_XR_SHOW_CONTROLLERS (1 << 16)
+#define V3D_XR_SHOW_CUSTOM_OVERLAYS (1 << 17)
 
 /** #View3D.gp_flag (short) */
 #define V3D_GP_FADE_OBJECTS (1 << 0) /* Fade all non GP objects */
diff --git a/source/blender/makesdna/DNA_xr_types.h b/source/blender/makesdna/DNA_xr_types.h
index a9d427777f7..6f4f7e3e8ae 100644
--- a/source/blender/makesdna/DNA_xr_types.h
+++ b/source/blender/makesdna/DNA_xr_types.h
@@ -42,7 +42,9 @@ typedef struct XrSessionSettings {
 
   /** View3D draw flags (V3D_OFSDRAW_NONE, V3D_OFSDRAW_SHOW_ANNOTATION, ...). */
   char draw_flags;
-  char _pad2[3];
+  /** Draw style for controller visualization. */
+  char controller_draw_style;
+  char _pad2[2];
 
   /** Clipping distance. */
   float clip_start, clip_end;
@@ -61,6 +63,13 @@ typedef enum eXRSessionBasePoseType {
   XR_BASE_POSE_CUSTOM = 2,
 } eXRSessionBasePoseType;
 
+typedef enum eXrSessionControllerDrawStyle {
+  XR_CONTROLLER_DRAW_DARK = 0,
+  XR_CONTROLLER_DRAW_LIGHT = 1,
+  XR_CONTROLLER_DRAW_DARK_RAY = 2,
+  XR_CONTROLLER_DRAW_LIGHT_RAY = 3,
+} eXrSessionControllerDrawStyle;
+
 /** XR action type. Enum values match those in GHOST_XrActionType enum for consistency. */
 typedef enum eXrActionType {
   XR_BOOLEAN_INPUT = 1,