1/**************************************************************************/
2/* openxr_util.cpp */
3/**************************************************************************/
4/* This file is part of: */
5/* GODOT ENGINE */
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8/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
9/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
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29/**************************************************************************/
30
31#include "openxr_util.h"
32
33#include <openxr/openxr_reflection.h>
34
35#include <math.h>
36
37#define XR_ENUM_CASE_STR(name, val) \
38 case name: \
39 return #name;
40#define XR_ENUM_SWITCH(enumType, var) \
41 switch (var) { \
42 XR_LIST_ENUM_##enumType(XR_ENUM_CASE_STR) default : return "Unknown " #enumType ": " + String::num_int64(int64_t(var)); \
43 }
44
45String OpenXRUtil::get_view_configuration_name(XrViewConfigurationType p_view_configuration){
46 XR_ENUM_SWITCH(XrViewConfigurationType, p_view_configuration)
47}
48
49String OpenXRUtil::get_reference_space_name(XrReferenceSpaceType p_reference_space){
50 XR_ENUM_SWITCH(XrReferenceSpaceType, p_reference_space)
51}
52
53String OpenXRUtil::get_structure_type_name(XrStructureType p_structure_type){
54 XR_ENUM_SWITCH(XrStructureType, p_structure_type)
55}
56
57String OpenXRUtil::get_session_state_name(XrSessionState p_session_state){
58 XR_ENUM_SWITCH(XrSessionState, p_session_state)
59}
60
61String OpenXRUtil::get_action_type_name(XrActionType p_action_type){
62 XR_ENUM_SWITCH(XrActionType, p_action_type)
63}
64
65String OpenXRUtil::get_environment_blend_mode_name(XrEnvironmentBlendMode p_blend_mode) {
66 XR_ENUM_SWITCH(XrEnvironmentBlendMode, p_blend_mode);
67}
68
69String OpenXRUtil::make_xr_version_string(XrVersion p_version) {
70 String version;
71
72 version += String::num_int64(XR_VERSION_MAJOR(p_version));
73 version += String(".");
74 version += String::num_int64(XR_VERSION_MINOR(p_version));
75 version += String(".");
76 version += String::num_int64(XR_VERSION_PATCH(p_version));
77
78 return version;
79}
80
81// Copied from OpenXR xr_linear.h private header, so we can still link against
82// system-provided packages without relying on our `thirdparty` code.
83
84// Copyright (c) 2017 The Khronos Group Inc.
85// Copyright (c) 2016 Oculus VR, LLC.
86//
87// SPDX-License-Identifier: Apache-2.0
88
89// Creates a projection matrix based on the specified dimensions.
90// The projection matrix transforms -Z=forward, +Y=up, +X=right to the appropriate clip space for the graphics API.
91// The far plane is placed at infinity if farZ <= nearZ.
92// An infinite projection matrix is preferred for rasterization because, except for
93// things *right* up against the near plane, it always provides better precision:
94// "Tightening the Precision of Perspective Rendering"
95// Paul Upchurch, Mathieu Desbrun
96// Journal of Graphics Tools, Volume 16, Issue 1, 2012
97void OpenXRUtil::XrMatrix4x4f_CreateProjection(XrMatrix4x4f *result, GraphicsAPI graphicsApi, const float tanAngleLeft,
98 const float tanAngleRight, const float tanAngleUp, float const tanAngleDown,
99 const float nearZ, const float farZ) {
100 const float tanAngleWidth = tanAngleRight - tanAngleLeft;
101
102 // Set to tanAngleDown - tanAngleUp for a clip space with positive Y down (Vulkan).
103 // Set to tanAngleUp - tanAngleDown for a clip space with positive Y up (OpenGL / D3D / Metal).
104 const float tanAngleHeight = graphicsApi == GRAPHICS_VULKAN ? (tanAngleDown - tanAngleUp) : (tanAngleUp - tanAngleDown);
105
106 // Set to nearZ for a [-1,1] Z clip space (OpenGL / OpenGL ES).
107 // Set to zero for a [0,1] Z clip space (Vulkan / D3D / Metal).
108 const float offsetZ = (graphicsApi == GRAPHICS_OPENGL || graphicsApi == GRAPHICS_OPENGL_ES) ? nearZ : 0;
109
110 if (farZ <= nearZ) {
111 // place the far plane at infinity
112 result->m[0] = 2.0f / tanAngleWidth;
113 result->m[4] = 0.0f;
114 result->m[8] = (tanAngleRight + tanAngleLeft) / tanAngleWidth;
115 result->m[12] = 0.0f;
116
117 result->m[1] = 0.0f;
118 result->m[5] = 2.0f / tanAngleHeight;
119 result->m[9] = (tanAngleUp + tanAngleDown) / tanAngleHeight;
120 result->m[13] = 0.0f;
121
122 result->m[2] = 0.0f;
123 result->m[6] = 0.0f;
124 result->m[10] = -1.0f;
125 result->m[14] = -(nearZ + offsetZ);
126
127 result->m[3] = 0.0f;
128 result->m[7] = 0.0f;
129 result->m[11] = -1.0f;
130 result->m[15] = 0.0f;
131 } else {
132 // normal projection
133 result->m[0] = 2.0f / tanAngleWidth;
134 result->m[4] = 0.0f;
135 result->m[8] = (tanAngleRight + tanAngleLeft) / tanAngleWidth;
136 result->m[12] = 0.0f;
137
138 result->m[1] = 0.0f;
139 result->m[5] = 2.0f / tanAngleHeight;
140 result->m[9] = (tanAngleUp + tanAngleDown) / tanAngleHeight;
141 result->m[13] = 0.0f;
142
143 result->m[2] = 0.0f;
144 result->m[6] = 0.0f;
145 result->m[10] = -(farZ + offsetZ) / (farZ - nearZ);
146 result->m[14] = -(farZ * (nearZ + offsetZ)) / (farZ - nearZ);
147
148 result->m[3] = 0.0f;
149 result->m[7] = 0.0f;
150 result->m[11] = -1.0f;
151 result->m[15] = 0.0f;
152 }
153}
154
155// Creates a projection matrix based on the specified FOV.
156void OpenXRUtil::XrMatrix4x4f_CreateProjectionFov(XrMatrix4x4f *result, GraphicsAPI graphicsApi, const XrFovf fov,
157 const float nearZ, const float farZ) {
158 const float tanLeft = tanf(fov.angleLeft);
159 const float tanRight = tanf(fov.angleRight);
160
161 const float tanDown = tanf(fov.angleDown);
162 const float tanUp = tanf(fov.angleUp);
163
164 XrMatrix4x4f_CreateProjection(result, graphicsApi, tanLeft, tanRight, tanUp, tanDown, nearZ, farZ);
165}
166