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[OpenXR] Fix LOCAL_FLOOR emulation on HTC Vive XR Elite #93678

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merged 1 commit into from
Jun 28, 2024
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[OpenXR] Fix LOCAL_FLOOR emulation on HTC Vive XR Elite #93678

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140 changes: 82 additions & 58 deletions modules/openxr/openxr_api.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -902,6 +902,47 @@ bool OpenXRAPI::setup_play_space() {

new_reference_space = XR_REFERENCE_SPACE_TYPE_LOCAL;
will_emulate_local_floor = true;

if (local_floor_emulation.local_space == XR_NULL_HANDLE) {
XrReferenceSpaceCreateInfo create_info = {
XR_TYPE_REFERENCE_SPACE_CREATE_INFO, // type
nullptr, // next
XR_REFERENCE_SPACE_TYPE_LOCAL, // referenceSpaceType
identityPose, // poseInReferenceSpace
};

XrResult result = xrCreateReferenceSpace(session, &create_info, &local_floor_emulation.local_space);
if (XR_FAILED(result)) {
print_line("OpenXR: Failed to create LOCAL space in order to emulate LOCAL_FLOOR [", get_error_string(result), "]");
will_emulate_local_floor = false;
}
}

if (local_floor_emulation.stage_space == XR_NULL_HANDLE) {
XrReferenceSpaceCreateInfo create_info = {
XR_TYPE_REFERENCE_SPACE_CREATE_INFO, // type
nullptr, // next
XR_REFERENCE_SPACE_TYPE_STAGE, // referenceSpaceType
identityPose, // poseInReferenceSpace
};

XrResult result = xrCreateReferenceSpace(session, &create_info, &local_floor_emulation.stage_space);
if (XR_FAILED(result)) {
print_line("OpenXR: Failed to create STAGE space in order to emulate LOCAL_FLOOR [", get_error_string(result), "]");
will_emulate_local_floor = false;
}
}

if (!will_emulate_local_floor) {
if (local_floor_emulation.local_space != XR_NULL_HANDLE) {
xrDestroySpace(local_floor_emulation.local_space);
local_floor_emulation.local_space = XR_NULL_HANDLE;
}
if (local_floor_emulation.stage_space != XR_NULL_HANDLE) {
xrDestroySpace(local_floor_emulation.stage_space);
local_floor_emulation.stage_space = XR_NULL_HANDLE;
}
}
} else {
// Fallback on LOCAL, which all OpenXR runtimes are required to support.
print_verbose(String("OpenXR: ") + OpenXRUtil::get_reference_space_name(requested_reference_space) + String(" isn't supported, defaulting to LOCAL space."));
Expand Down Expand Up @@ -931,16 +972,11 @@ bool OpenXRAPI::setup_play_space() {
play_space = new_play_space;
reference_space = new_reference_space;

emulating_local_floor = will_emulate_local_floor;
if (emulating_local_floor) {
// We'll use the STAGE space to get the floor height, but we can't do that until
// after xrWaitFrame(), so just set this flag for now.
// Render state will be updated then.
should_reset_emulated_floor_height = true;
} else {
// Update render state so this play space is used rendering the upcoming frame.
set_render_play_space(play_space);
}
local_floor_emulation.enabled = will_emulate_local_floor;
local_floor_emulation.should_reset_floor_height = will_emulate_local_floor;

// Update render state so this play space is used rendering the upcoming frame.
set_render_play_space(play_space);

return true;
}
Expand Down Expand Up @@ -975,63 +1011,39 @@ bool OpenXRAPI::setup_view_space() {
}

bool OpenXRAPI::reset_emulated_floor_height() {
ERR_FAIL_COND_V(!emulating_local_floor, false);

// This is based on the example code in the OpenXR spec which shows how to
// emulate LOCAL_FLOOR if it's not supported.
// See: https://registry.khronos.org/OpenXR/specs/1.0/html/xrspec.html#XR_EXT_local_floor
ERR_FAIL_COND_V(!local_floor_emulation.enabled, false);
ERR_FAIL_COND_V(local_floor_emulation.local_space == XR_NULL_HANDLE, false);
ERR_FAIL_COND_V(local_floor_emulation.stage_space == XR_NULL_HANDLE, false);

XrResult result;

XrPosef identityPose = {
{ 0.0, 0.0, 0.0, 1.0 },
{ 0.0, 0.0, 0.0 }
};

XrSpace local_space = XR_NULL_HANDLE;
XrSpace stage_space = XR_NULL_HANDLE;

XrReferenceSpaceCreateInfo create_info = {
XR_TYPE_REFERENCE_SPACE_CREATE_INFO, // type
nullptr, // next
XR_REFERENCE_SPACE_TYPE_LOCAL, // referenceSpaceType
identityPose, // poseInReferenceSpace
};

result = xrCreateReferenceSpace(session, &create_info, &local_space);
if (XR_FAILED(result)) {
print_line("OpenXR: Failed to create LOCAL space in order to emulate LOCAL_FLOOR [", get_error_string(result), "]");
return false;
}

create_info.referenceSpaceType = XR_REFERENCE_SPACE_TYPE_STAGE;
result = xrCreateReferenceSpace(session, &create_info, &stage_space);
if (XR_FAILED(result)) {
print_line("OpenXR: Failed to create STAGE space in order to emulate LOCAL_FLOOR [", get_error_string(result), "]");
xrDestroySpace(local_space);
return false;
}

XrSpaceLocation stage_location = {
XR_TYPE_SPACE_LOCATION, // type
nullptr, // next
0, // locationFlags
identityPose, // pose
{ { 0.0, 0.0, 0.0, 1.0 }, { 0.0, 0.0, 0.0 } }, // pose
};

result = xrLocateSpace(stage_space, local_space, get_predicted_display_time(), &stage_location);

xrDestroySpace(local_space);
xrDestroySpace(stage_space);
result = xrLocateSpace(local_floor_emulation.stage_space, local_floor_emulation.local_space, get_predicted_display_time(), &stage_location);

if (XR_FAILED(result)) {
print_line("OpenXR: Failed to locate STAGE space in LOCAL space, in order to emulate LOCAL_FLOOR [", get_error_string(result), "]");
return false;
}

XrPosef pose = {
{ 0.0, 0.0, 0.0, 1.0 },
{ 0.0, stage_location.pose.position.y, 0.0 }
};

XrReferenceSpaceCreateInfo create_info = {
XR_TYPE_REFERENCE_SPACE_CREATE_INFO, // type
nullptr, // next
XR_REFERENCE_SPACE_TYPE_LOCAL, // referenceSpaceType
pose, // poseInReferenceSpace
};

XrSpace new_play_space;
create_info.referenceSpaceType = XR_REFERENCE_SPACE_TYPE_LOCAL;
create_info.poseInReferenceSpace.position.y = stage_location.pose.position.y;
result = xrCreateReferenceSpace(session, &create_info, &new_play_space);
if (XR_FAILED(result)) {
print_line("OpenXR: Failed to recreate emulated LOCAL_FLOOR play space with latest floor estimate [", get_error_string(result), "]");
Expand Down Expand Up @@ -1275,6 +1287,16 @@ void OpenXRAPI::destroy_session() {
xrDestroySpace(view_space);
view_space = XR_NULL_HANDLE;
}
if (local_floor_emulation.local_space != XR_NULL_HANDLE) {
xrDestroySpace(local_floor_emulation.local_space);
local_floor_emulation.local_space = XR_NULL_HANDLE;
}
if (local_floor_emulation.stage_space != XR_NULL_HANDLE) {
xrDestroySpace(local_floor_emulation.stage_space);
local_floor_emulation.stage_space = XR_NULL_HANDLE;
}
local_floor_emulation.enabled = false;
local_floor_emulation.should_reset_floor_height = false;

if (supported_reference_spaces != nullptr) {
// free previous results
Expand Down Expand Up @@ -1953,8 +1975,8 @@ bool OpenXRAPI::poll_events() {
XrEventDataReferenceSpaceChangePending *event = (XrEventDataReferenceSpaceChangePending *)&runtimeEvent;

print_verbose(String("OpenXR EVENT: reference space type ") + OpenXRUtil::get_reference_space_name(event->referenceSpaceType) + " change pending!");
if (emulating_local_floor) {
should_reset_emulated_floor_height = true;
if (local_floor_emulation.enabled) {
local_floor_emulation.should_reset_floor_height = true;
}
if (event->poseValid && xr_interface) {
xr_interface->on_pose_recentered();
Expand Down Expand Up @@ -2097,16 +2119,18 @@ bool OpenXRAPI::process() {

set_render_display_info(frame_state.predictedDisplayTime, frame_state.shouldRender);

// This is before setup_play_space() to ensure that it happens on the frame after
// the play space has been created.
if (unlikely(local_floor_emulation.should_reset_floor_height && !play_space_is_dirty)) {
reset_emulated_floor_height();
local_floor_emulation.should_reset_floor_height = false;
}

if (unlikely(play_space_is_dirty)) {
setup_play_space();
play_space_is_dirty = false;
}

if (unlikely(should_reset_emulated_floor_height)) {
reset_emulated_floor_height();
should_reset_emulated_floor_height = false;
}

for (OpenXRExtensionWrapper *wrapper : registered_extension_wrappers) {
wrapper->on_process();
}
Expand Down
12 changes: 10 additions & 2 deletions modules/openxr/openxr_api.h
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Original file line number Diff line number Diff line change
Expand Up @@ -165,8 +165,16 @@ class OpenXRAPI {
XrSpace view_space = XR_NULL_HANDLE;
XRPose::TrackingConfidence head_pose_confidence = XRPose::XR_TRACKING_CONFIDENCE_NONE;

bool emulating_local_floor = false;
bool should_reset_emulated_floor_height = false;
// When LOCAL_FLOOR isn't supported, we use an approach based on the example code in the
// OpenXR spec in order to emulate it.
// See: https://registry.khronos.org/OpenXR/specs/1.0/html/xrspec.html#XR_EXT_local_floor
struct LocalFloorEmulation {
bool enabled = false;
XrSpace local_space = XR_NULL_HANDLE;
XrSpace stage_space = XR_NULL_HANDLE;
bool should_reset_floor_height = false;
} local_floor_emulation;

bool reset_emulated_floor_height();

bool load_layer_properties();
Expand Down
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