From d0f2b01a06ffe904faad14ae314f69773190800e Mon Sep 17 00:00:00 2001
From: ForTehLose <fortehlose@gmail.com>
Date: Tue, 3 Sep 2024 14:05:45 -0400
Subject: [PATCH] added an emulated local floor

---
 .../bevy_openxr/examples/common_entities.rs   | 104 +++++++++++++++++-
 1 file changed, 100 insertions(+), 4 deletions(-)

diff --git a/crates/bevy_openxr/examples/common_entities.rs b/crates/bevy_openxr/examples/common_entities.rs
index 20c3da1..4c7ae4b 100644
--- a/crates/bevy_openxr/examples/common_entities.rs
+++ b/crates/bevy_openxr/examples/common_entities.rs
@@ -8,13 +8,14 @@ use bevy_mod_openxr::{
     action_set_attaching::OxrAttachActionSet,
     action_set_syncing::{OxrActionSetSyncSet, OxrSyncActionSet},
     add_xr_plugins,
-    resources::OxrInstance,
+    helper_traits::{ToQuat, ToVec3},
+    resources::{OxrFrameState, OxrInstance, Pipelined},
     session::OxrSession,
-    spaces::OxrSpaceExt,
+    spaces::{OxrSpaceExt, OxrSpaceLocationFlags, OxrSpaceSyncSet, OxrSpaceVelocityFlags},
 };
 use bevy_mod_xr::{
     session::{session_available, session_running, XrSessionCreated, XrTrackingRoot},
-    spaces::XrSpace,
+    spaces::{XrPrimaryReferenceSpace, XrReferenceSpace, XrSpace, XrVelocity},
     types::XrPose,
 };
 use openxr::Posef;
@@ -37,6 +38,16 @@ fn main() {
     app.add_systems(XrSessionCreated, attach_set);
     app.add_systems(Startup, create_actions.run_if(session_available));
 
+    //head space
+    app.add_systems(
+        PreUpdate,
+        update_head_transforms
+            .in_set(OxrSpaceSyncSet)
+            .run_if(session_running),
+    );
+    //local floor emulated
+    app.add_systems(PreUpdate, update_local_floor.after(update_head_transforms));
+
     app.run();
 }
 
@@ -163,6 +174,91 @@ fn spawn_hands(
             right_space,
         ))
         .id();
+    //head?
+    let head_space = session
+        .create_reference_space(openxr::ReferenceSpaceType::VIEW, Transform::IDENTITY)
+        .unwrap();
+    let head = cmds
+        .spawn((
+            PbrBundle {
+                mesh: meshes.add(Cuboid::new(0.2, 0.2, 0.2)),
+                material: materials.add(Color::srgb_u8(255, 144, 144)),
+                transform: Transform::from_xyz(0.0, 0.0, 0.0),
+                ..default()
+            },
+            HeadXRSpace(head_space),
+        ))
+        .id();
+    //local_floor? emulated
+    let local_floor = cmds
+        .spawn((
+            PbrBundle {
+                mesh: meshes.add(Cuboid::new(0.5, 0.1, 0.5)),
+                material: materials.add(Color::srgb_u8(144, 255, 144)),
+                transform: Transform::from_xyz(0.0, 0.0, 0.0),
+                ..default()
+            },
+            LocalFloor,
+        ))
+        .id();
 
-    cmds.entity(root.single()).push_children(&[left, right]);
+    cmds.entity(root.single())
+        .push_children(&[left, right, head, local_floor]);
+}
+
+#[derive(Component)]
+struct HeadXRSpace(XrReferenceSpace);
+
+#[allow(clippy::type_complexity)]
+fn update_head_transforms(
+    session: Res<OxrSession>,
+    default_ref_space: Res<XrPrimaryReferenceSpace>,
+    pipelined: Option<Res<Pipelined>>,
+    frame_state: Res<OxrFrameState>,
+    mut query: Query<(&mut Transform, &HeadXRSpace, Option<&XrReferenceSpace>)>,
+) {
+    for (mut transform, space, ref_space) in &mut query {
+        let ref_space = ref_space.unwrap_or(&default_ref_space);
+        let time = if pipelined.is_some() {
+            openxr::Time::from_nanos(
+                frame_state.predicted_display_time.as_nanos()
+                    + frame_state.predicted_display_period.as_nanos(),
+            )
+        } else {
+            frame_state.predicted_display_time
+        };
+        let space_location = session.locate_space(&space.0, ref_space, time);
+
+        if let Ok(space_location) = space_location {
+            let flags = OxrSpaceLocationFlags(space_location.location_flags);
+            if flags.pos_valid() {
+                transform.translation = space_location.pose.position.to_vec3();
+            }
+            if flags.rot_valid() {
+                transform.rotation = space_location.pose.orientation.to_quat();
+            }
+        }
+    }
+}
+
+//emulated local_floor
+#[derive(Component)]
+struct LocalFloor;
+
+fn update_local_floor(
+    mut headSpace: Query<&mut Transform, (With<HeadXRSpace>, Without<LocalFloor>)>,
+    mut local_floor: Query<&mut Transform, (With<LocalFloor>, Without<HeadXRSpace>)>,
+) {
+    let head_transform = headSpace.get_single_mut();
+    match head_transform {
+        Ok(head) => {
+            let mut calc_floor = head.clone();
+            calc_floor.translation.y = 0.0;
+            calc_floor.rotation = Quat::IDENTITY;
+            for (mut transform) in &mut local_floor {
+                *transform = calc_floor;
+            }
+        }
+        Err(_) => (),
+    }
 }