4 files changed, 42 insertions, 1 deletions

diff --git a/source/blender/makesrna/intern/rna_xr.c b/source/blender/makesrna/intern/rna_xr.c
index b08e48a4b17..04a8500d136 100644
--- a/source/blender/makesrna/intern/rna_xr.c
+++ b/source/blender/makesrna/intern/rna_xr.c
@@ -45,6 +45,16 @@ static bool rna_XrSessionState_is_running(bContext *C)
 #  endif
 }
 
+static void rna_XrSessionState_reset_to_base_pose(bContext *C)
+{
+#  ifdef WITH_XR_OPENXR
+  wmWindowManager *wm = CTX_wm_manager(C);
+  WM_xr_session_base_pose_reset(&wm->xr);
+#  else
+  UNUSED_VARS(C);
+#  endif
+}
+
 #  ifdef WITH_XR_OPENXR
 static wmXrData *rna_XrSessionState_wm_xr_data_get(PointerRNA *ptr)
 {
@@ -197,6 +207,12 @@ static void rna_def_xr_session_state(BlenderRNA *brna)
   parm = RNA_def_boolean(func, "result", 0, "Result", "");
   RNA_def_function_return(func, parm);
 
+  func = RNA_def_function(srna, "reset_to_base_pose", "rna_XrSessionState_reset_to_base_pose");
+  RNA_def_function_ui_description(func, "Force resetting of position and rotation deltas");
+  RNA_def_function_flag(func, FUNC_NO_SELF);
+  parm = RNA_def_pointer(func, "context", "Context", "", "");
+  RNA_def_parameter_flags(parm, PROP_NEVER_NULL, PARM_REQUIRED);
+
   prop = RNA_def_property(srna, "viewer_pose_location", PROP_FLOAT, PROP_TRANSLATION);
   RNA_def_property_array(prop, 3);
   RNA_def_property_float_funcs(prop, "rna_XrSessionState_viewer_pose_location_get", NULL, NULL);
diff --git a/source/blender/windowmanager/WM_api.h b/source/blender/windowmanager/WM_api.h
index 2f540262a66..219060933f0 100644
--- a/source/blender/windowmanager/WM_api.h
+++ b/source/blender/windowmanager/WM_api.h
@@ -872,6 +872,7 @@ void WM_generic_user_data_free(struct wmGenericUserData *user_data);
 bool WM_xr_session_exists(const wmXrData *xr);
 bool WM_xr_session_is_ready(const wmXrData *xr);
 struct wmXrSessionState *WM_xr_session_state_handle_get(const wmXrData *xr);
+void WM_xr_session_base_pose_reset(wmXrData *xr);
 bool WM_xr_session_state_viewer_pose_location_get(const wmXrData *xr, float r_location[3]);
 bool WM_xr_session_state_viewer_pose_rotation_get(const wmXrData *xr, float r_rotation[4]);
 bool WM_xr_session_state_viewer_pose_matrix_info_get(const wmXrData *xr,
diff --git a/source/blender/windowmanager/xr/intern/wm_xr_intern.h b/source/blender/windowmanager/xr/intern/wm_xr_intern.h
index b53ae45a29f..9b7e9a15948 100644
--- a/source/blender/windowmanager/xr/intern/wm_xr_intern.h
+++ b/source/blender/windowmanager/xr/intern/wm_xr_intern.h
@@ -34,11 +34,16 @@ typedef struct wmXrSessionState {
   float viewer_viewmat[4][4];
   float focal_len;
 
+  /** Copy of XrSessionSettings.base_pose_ data to detect changes that need
+   * resetting to base pose. */
+  char prev_base_pose_type; /* eXRSessionBasePoseType */
+  Object *prev_base_pose_object;
   /** Copy of XrSessionSettings.flag created on the last draw call, stored to detect changes. */
   int prev_settings_flag;
   /** Copy of wmXrDrawData.eye_position_ofs. */
   float prev_eye_position_ofs[3];
 
+  bool force_reset_to_base_pose;
   bool is_view_data_set;
 } wmXrSessionState;
 
diff --git a/source/blender/windowmanager/xr/intern/wm_xr_session.c b/source/blender/windowmanager/xr/intern/wm_xr_session.c
index dc228d1b18b..e9ff38c5a92 100644
--- a/source/blender/windowmanager/xr/intern/wm_xr_session.c
+++ b/source/blender/windowmanager/xr/intern/wm_xr_session.c
@@ -95,6 +95,11 @@ bool WM_xr_session_exists(const wmXrData *xr)
   return xr->runtime && xr->runtime->context && xr->runtime->session_state.is_started;
 }
 
+void WM_xr_session_base_pose_reset(wmXrData *xr)
+{
+  xr->runtime->session_state.force_reset_to_base_pose = true;
+}
+
 /**
  * Check if the session is running, according to the OpenXR definition.
  */
@@ -154,6 +159,17 @@ static void wm_xr_session_draw_data_populate(wmXrData *xr_data,
   wm_xr_session_base_pose_calc(r_draw_data->scene, settings, &r_draw_data->base_pose);
 }
 
+static bool wm_xr_session_draw_data_needs_reset_to_base_pose(const wmXrSessionState *state,
+                                                             const XrSessionSettings *settings)
+{
+  if (state->force_reset_to_base_pose) {
+    return true;
+  }
+  return ((settings->flag & XR_SESSION_USE_POSITION_TRACKING) == 0) &&
+         ((state->prev_base_pose_type != settings->base_pose_type) ||
+          (state->prev_base_pose_object != settings->base_pose_object));
+}
+
 void wm_xr_session_draw_data_update(const wmXrSessionState *state,
                                     const XrSessionSettings *settings,
                                     const GHOST_XrDrawViewInfo *draw_view,
@@ -166,7 +182,8 @@ void wm_xr_session_draw_data_update(const wmXrSessionState *state,
 
   /* Set the eye position offset, it's used to offset the base pose when changing positional
    * tracking. */
-  if (!state->is_view_data_set) {
+  if (!state->is_view_data_set ||
+      wm_xr_session_draw_data_needs_reset_to_base_pose(state, settings)) {
     /* Always use the exact base pose with no offset when starting the session. */
     copy_v3_fl(draw_data->eye_position_ofs, 0.0f);
   }
@@ -223,6 +240,8 @@ void wm_xr_session_state_update(const XrSessionSettings *settings,
 
   copy_v3_v3(state->prev_eye_position_ofs, draw_data->eye_position_ofs);
   state->prev_settings_flag = settings->flag;
+  state->prev_base_pose_type = settings->base_pose_type;
+  state->prev_base_pose_object = settings->base_pose_object;
   state->is_view_data_set = true;
 }