st/oxr: Implement dpad emulation

src/xrt/state_trackers/oxr/oxr_api_action.c

@@ -84,11 +84,16 @@ process_dpad(struct oxr_logger *log,
 	for (size_t i = 0; i < ARRAY_SIZE(entry->dpads); i++) {
 		// Have we found a empty slot, add it.
 		if (entry->dpads[i].binding == XR_NULL_PATH) {
-			entry->dpads[i] = *dpad;
-
-			// Don't leave potentially dangling pointers.
-			entry->dpads[i].next = NULL;
-			entry->dpads[i].actionSet = XR_NULL_HANDLE;
+			struct oxr_dpad_binding_modification dpad_binding = {
+			    .binding = dpad->binding,
+			    .settings = {
+			        .forceThreshold = dpad->forceThreshold,
+			        .forceThresholdReleased = dpad->forceThresholdReleased,
+			        .centerRegion = dpad->centerRegion,
+			        .wedgeAngle = dpad->wedgeAngle,
+			        .isSticky = dpad->isSticky,
+			    }};
+			entry->dpads[i] = dpad_binding;
 
 			entry->dpad_count++;
 			added = true;

src/xrt/state_trackers/oxr/oxr_dpad.c

@@ -63,7 +63,7 @@ oxr_dpad_state_get_or_add(struct oxr_dpad_state *state, uint64_t key)
 void
 oxr_dpad_state_deinit(struct oxr_dpad_state *state)
 {
-	if (state->uhi != NULL) {
+	if (state != NULL && state->uhi != NULL) {
 		u_hashmap_int_clear_and_call_for_each(state->uhi, destroy_callback, NULL);
 		u_hashmap_int_destroy(&state->uhi);
 	}

src/xrt/state_trackers/oxr/oxr_input.c

@@ -1258,6 +1258,115 @@ oxr_action_populate_input_transform(struct oxr_logger *log,
 	return oxr_input_transform_create_chain(log, slog, t, act->data->action_type, act->data->name, str,
 	                                        &action_input->transforms, &action_input->transform_count);
 }
+/*!
+ * Find dpad settings in @p dpad_entry whose binding path
+ * is a prefix of @p bound_path_string.
+ *
+ * @returns true if settings were found and written to @p out_dpad_settings
+ */
+static bool
+find_matching_dpad(struct oxr_logger *log,
+                   struct oxr_instance *inst,
+                   struct oxr_dpad_entry *dpad_entry,
+                   const char *bound_path_string,
+                   struct oxr_dpad_binding_modification **out_dpad_binding)
+{
+	if (dpad_entry != NULL) {
+		for (uint32_t i = 0; i < dpad_entry->dpad_count; i++) {
+			const char *dpad_path_string;
+			size_t dpad_path_length;
+			oxr_path_get_string(log, inst, dpad_entry->dpads[i].binding, &dpad_path_string,
+			                    &dpad_path_length);
+			if (strncmp(bound_path_string, dpad_path_string, dpad_path_length) == 0) {
+				*out_dpad_binding = &dpad_entry->dpads[i];
+				return true;
+			}
+		}
+	}
+	return false;
+}
+
+/*!
+ * Try to produce a transform chain to create a dpad button from the selected input
+ * (potentially using other inputs like `/force` in the process)
+ *
+ * Populates @p action_input->transforms and @p action_input->transform_count on
+ * success.
+ *
+ * @returns false if it could not, true if it could
+ */
+static bool
+oxr_action_populate_input_transform_dpad(struct oxr_logger *log,
+                                         struct oxr_sink_logger *slog,
+                                         struct oxr_session *sess,
+                                         struct oxr_action *act,
+                                         struct oxr_dpad_entry *dpad_entry,
+                                         enum oxr_dpad_region dpad_region,
+                                         struct oxr_interaction_profile *profile,
+                                         struct oxr_action_input *action_inputs,
+                                         uint32_t action_input_count,
+                                         uint32_t selected_input)
+{
+	struct oxr_action_input *action_input = &(action_inputs[selected_input]);
+	assert(action_input->transforms == NULL);
+	assert(action_input->transform_count == 0);
+
+	const char *bound_path_string;
+	size_t bound_path_length;
+	oxr_path_get_string(log, sess->sys->inst, action_input->bound_path, &bound_path_string, &bound_path_length);
+
+	// find correct dpad entry
+	struct oxr_dpad_binding_modification *dpad_binding_modification = NULL;
+	find_matching_dpad(log, sess->sys->inst, dpad_entry, bound_path_string, &dpad_binding_modification);
+
+	enum xrt_input_type t = XRT_GET_INPUT_TYPE(action_input->input->name);
+	enum xrt_input_type activate_t = XRT_GET_INPUT_TYPE(action_input->dpad_activate_name);
+
+	return oxr_input_transform_create_chain_dpad(
+	    log, slog, t, act->data->action_type, bound_path_string, dpad_binding_modification, dpad_region, activate_t,
+	    action_input->dpad_activate, &action_input->transforms, &action_input->transform_count);
+}
+
+// based on get_subaction_path_from_path
+static bool
+get_dpad_region_from_path(struct oxr_logger *log,
+                          struct oxr_instance *inst,
+                          XrPath path,
+                          enum oxr_dpad_region *out_dpad_region)
+{
+	const char *str = NULL;
+	size_t length = 0;
+	XrResult ret;
+
+	ret = oxr_path_get_string(log, inst, path, &str, &length);
+	if (ret != XR_SUCCESS) {
+		return false;
+	}
+
+	// TODO: surely there's a better way to do this?
+	if (length >= 10 && strncmp("/dpad_left", str + (length - 10), 10) == 0) {
+		*out_dpad_region = OXR_DPAD_REGION_LEFT;
+		return true;
+	}
+	if (length >= 11 && strncmp("/dpad_right", str + (length - 11), 11) == 0) {
+		*out_dpad_region = OXR_DPAD_REGION_RIGHT;
+		return true;
+	}
+	if (length >= 8 && strncmp("/dpad_up", str + (length - 8), 8) == 0) {
+		*out_dpad_region = OXR_DPAD_REGION_UP;
+		return true;
+	}
+	if (length >= 10 && strncmp("/dpad_down", str + (length - 10), 10) == 0) {
+		*out_dpad_region = OXR_DPAD_REGION_DOWN;
+		return true;
+	}
+	if (length >= 12 && strncmp("/dpad_center", str + (length - 12), 12) == 0) {
+		*out_dpad_region = OXR_DPAD_REGION_CENTER;
+		return true;
+	}
+
+	return false;
+}
 
 static void
 oxr_action_bind_io(struct oxr_logger *log,
@@ -1282,9 +1391,18 @@ oxr_action_bind_io(struct oxr_logger *log,
 		cache->current.active = true;
 		cache->inputs = U_TYPED_ARRAY_CALLOC(struct oxr_action_input, input_count);
 		for (uint32_t i = 0; i < input_count; i++) {
-
 			// Only add the input if we can find a transform.
-			if (oxr_action_populate_input_transform(log, slog, sess, act, &(inputs[i]))) {
+
+			enum oxr_dpad_region dpad_region;
+			if (get_dpad_region_from_path(log, sess->sys->inst, inputs[i].bound_path, &dpad_region)) {
+				struct oxr_dpad_entry *entry =
+				    oxr_dpad_state_get(&profile->dpad_state, act->act_set->act_set_key);
+				if (oxr_action_populate_input_transform_dpad(log, slog, sess, act, entry, dpad_region,
+				                                             profile, inputs, input_count, i)) {
+					cache->inputs[count++] = inputs[i];
+					continue;
+				}
+			} else if (oxr_action_populate_input_transform(log, slog, sess, act, &(inputs[i]))) {
 				cache->inputs[count++] = inputs[i];
 				continue;
 			}

src/xrt/state_trackers/oxr/oxr_input_transform.c

@@ -8,6 +8,8 @@
  * @ingroup oxr_input_transform
  */
 
+#include "math/m_mathinclude.h"
+
 #include "oxr_input_transform.h"
 #include "oxr_logger.h"
 #include "oxr_objects.h"
@@ -105,6 +107,30 @@ oxr_input_transform_init_vec2_get_y(struct oxr_input_transform *transform, const
 	return true;
 }
 
+bool
+oxr_input_transform_init_vec2_dpad(struct oxr_input_transform *transform,
+                                   const struct oxr_input_transform *parent,
+                                   struct oxr_dpad_settings dpad_settings,
+                                   enum oxr_dpad_region dpad_region,
+                                   enum xrt_input_type activation_input_type,
+                                   struct xrt_input *activation_input)
+{
+	assert(transform != NULL);
+	assert(parent != NULL);
+	assert(parent->result_type == XRT_INPUT_TYPE_VEC2_MINUS_ONE_TO_ONE);
+
+	U_ZERO(transform);
+	transform->type = INPUT_TRANSFORM_DPAD;
+	transform->result_type = XRT_INPUT_TYPE_BOOLEAN;
+	transform->data.dpad_state.settings = dpad_settings;
+	transform->data.dpad_state.bound_region = dpad_region;
+	transform->data.dpad_state.activation_input_type = activation_input_type;
+	transform->data.dpad_state.activation_input = activation_input;
+	transform->data.dpad_state.already_active = activation_input == NULL;
+
+	return true;
+}
+
 bool
 oxr_input_transform_init_threshold(struct oxr_input_transform *transform,
                                    const struct oxr_input_transform *parent,
@@ -148,7 +174,7 @@ oxr_input_transform_init_bool_to_vec1(struct oxr_input_transform *transform,
 }
 
 bool
-oxr_input_transform_process(const struct oxr_input_transform *transform,
+oxr_input_transform_process(struct oxr_input_transform *transform,
                             size_t transform_count,
                             const struct oxr_input_value_tagged *input,
                             struct oxr_input_value_tagged *out)
@@ -158,7 +184,7 @@ oxr_input_transform_process(const struct oxr_input_transform *transform,
 	}
 	struct oxr_input_value_tagged data = *input;
 	for (size_t i = 0; i < transform_count; ++i) {
-		const struct oxr_input_transform *xform = &(transform[i]);
+		struct oxr_input_transform *xform = &(transform[i]);
 		switch (xform->type) {
 		case INPUT_TRANSFORM_IDENTITY:
 			// do nothing
@@ -178,6 +204,75 @@ oxr_input_transform_process(const struct oxr_input_transform *transform,
 			    data.value.boolean ? xform->data.bool_to_vec1.true_val : xform->data.bool_to_vec1.false_val;
 			break;
 		}
+		case INPUT_TRANSFORM_DPAD: {
+			struct oxr_input_transform_dpad_data *dpad_state = &xform->data.dpad_state;
+
+			if (dpad_state->activation_input != NULL) {
+				bool active = true;
+
+				switch (dpad_state->activation_input_type) {
+				case XRT_INPUT_TYPE_BOOLEAN: {
+					active = dpad_state->activation_input->value.boolean;
+					break;
+				}
+				case XRT_INPUT_TYPE_VEC1_ZERO_TO_ONE: {
+					float force = dpad_state->activation_input->value.vec1.x;
+					active = (force >= dpad_state->settings.forceThreshold) ||
+					         (dpad_state->already_active &&
+					          force >= dpad_state->settings.forceThresholdReleased);
+					break;
+				}
+				default: active = false;
+				}
+
+				dpad_state->already_active = active;
+				if (!active) {
+					dpad_state->active_regions = OXR_DPAD_REGION_CENTER;
+					data.value.boolean = false;
+					break;
+				}
+			}
+
+			enum oxr_dpad_region bound_region = dpad_state->bound_region;
+			enum oxr_dpad_region active_regions = OXR_DPAD_REGION_CENTER;
+
+			for (int i = 0; i < 4; i++) {
+				enum oxr_dpad_region query_region = 1 << i;
+
+				bool rot90 =
+				    (query_region == OXR_DPAD_REGION_LEFT) || (query_region == OXR_DPAD_REGION_RIGHT);
+				bool rot180 =
+				    (query_region == OXR_DPAD_REGION_DOWN) || (query_region == OXR_DPAD_REGION_RIGHT);
+
+				float localX = rot90 ? data.value.vec2.y : data.value.vec2.x;
+				float localY = rot90 ? -data.value.vec2.x : data.value.vec2.y;
+				if (rot180) {
+					localX = -localX;
+					localY = -localY;
+				}
+
+				float centerRadius = dpad_state->settings.centerRegion;
+				if (localX * localX + localY * localY <= centerRadius * centerRadius) {
+					continue;
+				}
+
+				float tanXY = atan2f(localX, localY);
+				float halfAngle = dpad_state->settings.wedgeAngle / 2.0f;
+				if (-halfAngle < tanXY && tanXY <= halfAngle) {
+					active_regions |= query_region;
+				}
+			}
+
+			if (!dpad_state->already_active || !dpad_state->settings.isSticky ||
+			    (dpad_state->active_regions == OXR_DPAD_REGION_CENTER) ||
+			    (active_regions == OXR_DPAD_REGION_CENTER)) {
+				dpad_state->active_regions = active_regions;
+			}
+
+			data.value.boolean = (dpad_state->active_regions == bound_region) ||
+			                     ((dpad_state->active_regions & bound_region) != 0);
+			break;
+		}
 		case INPUT_TRANSFORM_INVALID:
 		default: return false;
 		}
@@ -346,3 +441,72 @@ oxr_input_transform_create_chain(struct oxr_logger *log,
 
 	return true;
 }
+
+bool
+oxr_input_transform_create_chain_dpad(struct oxr_logger *log,
+                                      struct oxr_sink_logger *slog,
+                                      enum xrt_input_type input_type,
+                                      XrActionType result_type,
+                                      const char *bound_path_string,
+                                      struct oxr_dpad_binding_modification *dpad_binding_modification,
+                                      enum oxr_dpad_region dpad_region,
+                                      enum xrt_input_type activation_input_type,
+                                      struct xrt_input *activation_input,
+                                      struct oxr_input_transform **out_transforms,
+                                      size_t *out_transform_count)
+{
+	struct oxr_input_transform chain[OXR_MAX_INPUT_TRANSFORMS] = {0};
+
+	// these default settings are specified by OpenXR and thus must not be changed
+	struct oxr_dpad_settings dpad_settings = {
+	    .forceThreshold = 0.5f,
+	    .forceThresholdReleased = 0.4f,
+	    .centerRegion = 0.5f,
+	    .wedgeAngle = M_PI_2,
+	    .isSticky = false,
+	};
+
+	if (dpad_binding_modification != NULL) {
+		dpad_settings = dpad_binding_modification->settings;
+	}
+
+	oxr_slog(slog, "\t\tAdding dpad transform from '%s' to '%s'\n", xr_action_type_to_str(result_type),
+	         xrt_input_type_to_str(input_type));
+
+	struct oxr_input_transform *current_xform = &(chain[0]);
+	if (!oxr_input_transform_init_root(current_xform, input_type)) {
+		*out_transform_count = 0;
+		*out_transforms = NULL;
+		return false;
+	}
+
+	// We start over here.
+	size_t transform_count = 0;
+	input_type = current_xform->result_type;
+	if (input_type != XRT_INPUT_TYPE_VEC2_MINUS_ONE_TO_ONE) {
+		oxr_slog(slog, "\t\t\tUnexpected input type for dpad binding %s\n", bound_path_string);
+		return false;
+	}
+	if (result_type != XR_ACTION_TYPE_BOOLEAN_INPUT) {
+		oxr_slog(slog, "\t\t\tUnexpected output type for dpad binding %s\n", bound_path_string);
+		return false;
+	}
+
+	struct oxr_input_transform *new_xform = &(chain[transform_count]);
+	if (!oxr_input_transform_init_vec2_dpad(new_xform, current_xform, dpad_settings, dpad_region,
+	                                        activation_input_type, activation_input)) {
+		// Error has already been logged.
+
+		*out_transform_count = 0;
+		*out_transforms = NULL;
+		return false;
+	}
+
+	current_xform = new_xform;
+	transform_count++;
+
+	*out_transform_count = transform_count;
+	*out_transforms = oxr_input_transform_clone_chain(chain, transform_count);
+
+	return true;
+}

src/xrt/state_trackers/oxr/oxr_input_transform.h

@@ -11,6 +11,7 @@
 #pragma once
 
 #include "xrt/xrt_device.h"
+#include "oxr_objects.h"
 
 // we need no platform-specific defines from OpenXR.
 #include "openxr/openxr.h"
@@ -80,6 +81,15 @@ enum oxr_input_transform_type
 	 * @see oxr_input_transform_bool_to_vec1_data
 	 */
 	INPUT_TRANSFORM_BOOL_TO_VEC1,
+
+	/*!
+	 * Interpret a 2D joystick or trackpad as a dpad.
+	 *
+	 * This transform type has data:
+	 *
+	 * @see oxr_input_transform_dpad_data
+	 */
+	INPUT_TRANSFORM_DPAD,
 };
 
 struct oxr_input_transform;
@@ -110,6 +120,21 @@ struct oxr_input_transform_bool_to_vec1_data
 	float false_val;
 };
 
+/*!
+ * Data required for INPUT_TRANSFORM_DPAD
+ * @see oxr_input_transform
+ * @see INPUT_TRANSFORM_DPAD
+ */
+struct oxr_input_transform_dpad_data
+{
+	enum oxr_dpad_region bound_region;
+	enum oxr_dpad_region active_regions;
+	struct oxr_dpad_settings settings;
+	enum xrt_input_type activation_input_type;
+	struct xrt_input *activation_input;
+	bool already_active;
+};
+
 /*!
  * Variant type for input transforms.
  *
@@ -139,6 +164,11 @@ struct oxr_input_transform
 		 * INPUT_TRANSFORM_BOOL_TO_VEC1
 		 */
 		struct oxr_input_transform_bool_to_vec1_data bool_to_vec1;
+		/*!
+		 * Populated when oxr_input_transform::type is
+		 * INPUT_TRANSFORM_DPAD
+		 */
+		struct oxr_input_transform_dpad_data dpad_state;
 	} data;
 };
 
@@ -173,7 +203,7 @@ oxr_input_transform_destroy(struct oxr_input_transform **transform_ptr);
  * @public @memberof oxr_input_transform
  */
 bool
-oxr_input_transform_process(const struct oxr_input_transform *transforms,
+oxr_input_transform_process(struct oxr_input_transform *transforms,
                             size_t transform_count,
                             const struct oxr_input_value_tagged *input,
                             struct oxr_input_value_tagged *out);
@@ -300,6 +330,40 @@ oxr_input_transform_create_chain(struct oxr_logger *log,
                                  struct oxr_input_transform **out_transforms,
                                  size_t *out_transform_count);
 
+/*!
+ * Create a transform array to process a 2D input plus activation input to a dpad.
+ *
+ * @param[in] log The logger
+ * @param[in] slog The sink logger
+ * @param[in] input_type The type of input received from the hardware
+ * @param[in] result_type The type of input the application requested
+ * @param[in] bound_path_string The path name string that has been bound.
+ * @param[in] dpad_settings The dpad settings provided by the application
+ * as a binding modification. NULL means use the defaults as per the spec.
+ * @param[in] dpad_region The dpad region associated with this binding
+ * @param[in] activation_input_type The type of the activation input
+ * @param[in] activation_input The activation input, i.e. the input used
+ * to determine when the emulated dpad buttons should activate
+ * @param[out] out_transforms A pointer that will be populated with the output
+ * array's address, or NULL.
+ * @param[out] out_transform_count Where to populate the array size
+ * @return false if not possible
+ *
+ * @relates oxr_input_transform
+ */
+bool
+oxr_input_transform_create_chain_dpad(struct oxr_logger *log,
+                                      struct oxr_sink_logger *slog,
+                                      enum xrt_input_type input_type,
+                                      XrActionType result_type,
+                                      const char *bound_path_string,
+                                      struct oxr_dpad_binding_modification *dpad_binding_modification,
+                                      enum oxr_dpad_region dpad_region,
+                                      enum xrt_input_type activation_input_type,
+                                      struct xrt_input *activation_input,
+                                      struct oxr_input_transform **out_transforms,
+                                      size_t *out_transform_count);
+
 /*!
  * @}
  */

src/xrt/state_trackers/oxr/oxr_objects.h

@@ -173,6 +173,18 @@ enum oxr_subaction_path
 	OXR_SUB_ACTION_PATH_GAMEPAD,
 };
 
+/*!
+ * Region of a dpad binding that an input is mapped to
+ */
+enum oxr_dpad_region
+{
+	OXR_DPAD_REGION_CENTER = 0,
+	OXR_DPAD_REGION_UP = (1 << 0),
+	OXR_DPAD_REGION_DOWN = (1 << 1),
+	OXR_DPAD_REGION_LEFT = (1 << 2),
+	OXR_DPAD_REGION_RIGHT = (1 << 3),
+};
+
 /*!
  * Tracks the state of a image that belongs to a @ref oxr_swapchain.
  */
@@ -1596,6 +1608,29 @@ oxr_session_success_focused_result(struct oxr_session *session)
 	}
 }
 
+/*!
+ * dpad settings we need extracted from XrInteractionProfileDpadBindingEXT
+ *
+ * @ingroup oxr_input
+ */
+struct oxr_dpad_settings
+{
+	float forceThreshold;
+	float forceThresholdReleased;
+	float centerRegion;
+	float wedgeAngle;
+	bool isSticky;
+};
+
+/*!
+ * dpad binding extracted from XrInteractionProfileDpadBindingEXT
+ */
+struct oxr_dpad_binding_modification
+{
+	XrPath binding;
+	struct oxr_dpad_settings settings;
+};
+
 /*!
  * A entry in the dpad state for one action set.
  *

src/xrt/state_trackers/oxr/oxr_pretty_print.c

@@ -9,6 +9,7 @@
 
 #include "oxr_objects.h" // For now needs to come before oxr_logger.h
 #include "oxr_logger.h"
+#include "oxr_input_transform.h"
 #include "oxr_pretty_print.h"
 
 

src/xrt/state_trackers/oxr/oxr_space.c

@@ -20,6 +20,7 @@
 #include "oxr_objects.h"
 #include "oxr_logger.h"
 #include "oxr_handle.h"
+#include "oxr_input_transform.h"
 #include "oxr_chain.h"
 #include "oxr_pretty_print.h"
 

tests/tests_input_transform.cpp

@@ -6,6 +6,8 @@
  * @author Ryan Pavlik <ryan.pavlik@collabora.com>
  */
 
+#include "math/m_mathinclude.h"
+
 #include "catch/catch.hpp"
 
 #include <xrt/xrt_defines.h>
@@ -315,3 +317,236 @@ TEST_CASE("input_transform")
 	oxr_input_transform_destroy(&transforms);
 	CHECK(NULL == transforms);
 }
+
+
+struct dpad_test_case
+{
+	float x;
+	float y;
+	enum oxr_dpad_region active_regions;
+};
+
+
+TEST_CASE("input_transform_dpad")
+{
+	struct oxr_logger log;
+	oxr_log_init(&log, "test");
+	struct oxr_sink_logger slog = {};
+
+	struct oxr_input_transform *transforms = NULL;
+	size_t transform_count = 0;
+
+	oxr_input_value_tagged input = {};
+	oxr_input_value_tagged output = {};
+
+	struct oxr_dpad_binding_modification *dpad_binding_modification = NULL;
+	enum xrt_input_type activation_input_type = XRT_INPUT_TYPE_VEC1_ZERO_TO_ONE;
+	struct xrt_input activation_input = {};
+	enum oxr_dpad_region dpad_region = OXR_DPAD_REGION_UP;
+
+	SECTION("Default settings")
+	{
+		XrActionType action_type = XR_ACTION_TYPE_BOOLEAN_INPUT;
+
+		SECTION("without an activation input")
+		{
+			input.type = XRT_INPUT_TYPE_VEC2_MINUS_ONE_TO_ONE;
+
+			CHECK(oxr_input_transform_create_chain_dpad(
+			    &log, &slog, input.type, action_type, "/dummy_vec2/dpad_up", dpad_binding_modification,
+			    dpad_region, activation_input_type, NULL, &transforms, &transform_count));
+			CHECK(transform_count == 1);
+			CHECK(transforms != nullptr);
+			CHECK(transforms[0].type == INPUT_TRANSFORM_DPAD);
+
+
+			SECTION("up region is off in center")
+			{
+				input.value.vec2.x = 0.0f;
+				input.value.vec2.y = 0.0f;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(false == output.value.boolean);
+			}
+
+			SECTION("up region is on when pointing up")
+			{
+				input.value.vec2.x = 0.0f;
+				input.value.vec2.y = 1.0f;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(true == output.value.boolean);
+			}
+
+			struct dpad_test_case cases[9] = {
+			    // obvious
+			    {0.0f, 0.0f, OXR_DPAD_REGION_CENTER},
+			    {0.0f, 1.0f, OXR_DPAD_REGION_UP},
+			    {0.0f, -1.0f, OXR_DPAD_REGION_DOWN},
+			    {-1.0f, 0.0f, OXR_DPAD_REGION_LEFT},
+			    {1.0f, 0.0f, OXR_DPAD_REGION_RIGHT},
+			    // boundary cases
+			    {1.0f, 1.0f, OXR_DPAD_REGION_UP},
+			    {-1.0f, -1.0f, OXR_DPAD_REGION_DOWN},
+			    {-1.0f, 1.0f, OXR_DPAD_REGION_LEFT},
+			    {1.0f, -1.0f, OXR_DPAD_REGION_RIGHT},
+			};
+
+			for (uint32_t i = 0; i < ARRAY_SIZE(cases); i++) {
+				DYNAMIC_SECTION("with (x, y) of (" << cases[i].x << ", " << cases[i].y << ")")
+				{
+					input.value.vec2.x = cases[i].x;
+					input.value.vec2.y = cases[i].y;
+					CHECK(
+					    oxr_input_transform_process(transforms, transform_count, &input, &output));
+					CHECK(cases[i].active_regions == transforms[0].data.dpad_state.active_regions);
+				}
+			}
+		}
+		SECTION("with a boolean activation input")
+		{
+			input.type = XRT_INPUT_TYPE_VEC2_MINUS_ONE_TO_ONE;
+			input.value.vec2.x = 0.0f;
+			input.value.vec2.y = 1.0f;
+
+			activation_input_type = XRT_INPUT_TYPE_BOOLEAN;
+
+			CHECK(oxr_input_transform_create_chain_dpad(
+			    &log, &slog, input.type, action_type, "/dummy_vec2/dpad_up", dpad_binding_modification,
+			    dpad_region, activation_input_type, &activation_input, &transforms, &transform_count));
+			CHECK(transform_count == 1);
+			CHECK(transforms != nullptr);
+			CHECK(transforms[0].type == INPUT_TRANSFORM_DPAD);
+
+			SECTION("when activation input is set to true")
+			{
+				activation_input.value.boolean = true;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(true == output.value.boolean);
+			}
+			SECTION("when activation input is set to false")
+			{
+				activation_input.value.boolean = false;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(false == output.value.boolean);
+			}
+		}
+		SECTION("with a float activation input")
+		{
+			input.type = XRT_INPUT_TYPE_VEC2_MINUS_ONE_TO_ONE;
+			input.value.vec2.x = 0.0f;
+			input.value.vec2.y = 1.0f;
+
+			activation_input_type = XRT_INPUT_TYPE_VEC1_ZERO_TO_ONE;
+
+			CHECK(oxr_input_transform_create_chain_dpad(
+			    &log, &slog, input.type, action_type, "/dummy_vec2/dpad_up", dpad_binding_modification,
+			    dpad_region, activation_input_type, &activation_input, &transforms, &transform_count));
+			CHECK(transform_count == 1);
+			CHECK(transforms != nullptr);
+			CHECK(transforms[0].type == INPUT_TRANSFORM_DPAD);
+
+			SECTION("when activation input is set to 1.0")
+			{
+				activation_input.value.vec1.x = 1.0f;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(true == output.value.boolean);
+			}
+			SECTION("when activation input is set to 0.0")
+			{
+				activation_input.value.vec1.x = 0.0f;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(false == output.value.boolean);
+			}
+			SECTION("when activation input varies")
+			{
+				activation_input.value.vec1.x = 0.45f;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(false == output.value.boolean);
+				activation_input.value.vec1.x = 0.6f;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(true == output.value.boolean);
+				activation_input.value.vec1.x = 0.45f;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(true == output.value.boolean);
+				activation_input.value.vec1.x = 0.35f;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(false == output.value.boolean);
+			}
+		}
+	}
+	SECTION("Sticky enabled")
+	{
+		XrActionType action_type = XR_ACTION_TYPE_BOOLEAN_INPUT;
+
+		struct oxr_dpad_binding_modification dpad_binding_modification_val = {
+		    XR_NULL_PATH, // XrPath binding, unused at this stage
+		    {
+		        0.5f,   // float forceThreshold
+		        0.4f,   // float forceThresholdReleased
+		        0.5f,   // float centerRegion
+		        M_PI_2, // float wedgeAngle
+		        true,   // bool isSticky
+		    }};
+		dpad_binding_modification = &dpad_binding_modification_val;
+
+		SECTION("without an activation input")
+		{
+			input.type = XRT_INPUT_TYPE_VEC2_MINUS_ONE_TO_ONE;
+			input.value.vec2.x = 0.0f;
+			input.value.vec2.y = 1.0f;
+
+			CHECK(oxr_input_transform_create_chain_dpad(
+			    &log, &slog, input.type, action_type, "/dummy_vec2/dpad_up", dpad_binding_modification,
+			    dpad_region, activation_input_type, NULL, &transforms, &transform_count));
+			CHECK(transform_count == 1);
+			CHECK(transforms != nullptr);
+			CHECK(transforms[0].type == INPUT_TRANSFORM_DPAD);
+
+			SECTION("up region is off in center")
+			{
+				input.value.vec2.x = 0.0f;
+				input.value.vec2.y = 0.0f;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(false == output.value.boolean);
+			}
+
+			SECTION("up region is on when pointing up")
+			{
+				input.value.vec2.x = 0.0f;
+				input.value.vec2.y = 1.0f;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(true == output.value.boolean);
+			}
+			SECTION("up region is off when pointing down")
+			{
+				input.value.vec2.x = 0.0f;
+				input.value.vec2.y = -1.0f;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(false == output.value.boolean);
+			}
+
+			SECTION("up region stays on when stick moves clockwise to down")
+			{
+				input.value.vec2.x = 0.0f;
+				input.value.vec2.y = 1.0f;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(true == output.value.boolean);
+				input.value.vec2.x = 1.0f;
+				input.value.vec2.y = 0.0f;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(true == output.value.boolean);
+				input.value.vec2.x = 0.0f;
+				input.value.vec2.y = -1.0f;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(true == output.value.boolean);
+				input.value.vec2.x = 0.0f;
+				input.value.vec2.y = 0.0f;
+				CHECK(oxr_input_transform_process(transforms, transform_count, &input, &output));
+				CHECK(false == output.value.boolean);
+			}
+		}
+	}
+
+	oxr_log_slog(&log, &slog);
+	oxr_input_transform_destroy(&transforms);
+	CHECK(NULL == transforms);
+}