OgreOpenXRInstance.cpp

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/*
    Skyscraper 2.0 - OpenXR Instance
    Portions Copyright (C)2024 Ryan Thoryk
    MIT license - see LICENSE file
    https://www.skyscrapersim.net
    https://sourceforge.net/projects/skyscraper/
    Contact - ryan@skyscrapersim.net
*/
 
/*
    Original work produced by Glastonbridge Software Limited. This code is provided under the MIT license.
    https://github.com/glastonbridge/OgreOpenXRRenderWindow
*/
 
#include "OgreOpenXRInstance.h"
 
#include <vector>
#include "XrUtility/XrError.h"
#include "XrUtility/XrDispatchTable.h"
 
Ogre::OpenXRInstance::OpenXRInstance()
{
}
 
Ogre::OpenXRInstance::~OpenXRInstance()
{
}
 
 
std::vector<const char*> SelectExtensions();
 
void Ogre::OpenXRInstance::Initialize(const std::string& applicationName)
{
  CHECK(m_instanceHandle.Get() == XR_NULL_HANDLE);
 
  std::vector<const char*> enabledExtensions = SelectExtensions();
 
  XrInstanceCreateInfo createInfo{ XR_TYPE_INSTANCE_CREATE_INFO };
  createInfo.enabledExtensionCount = (uint32_t)enabledExtensions.size();
  createInfo.enabledExtensionNames = enabledExtensions.data();
  createInfo.applicationInfo.applicationVersion = 1;
  createInfo.applicationInfo.engineName[0] = 0;
  createInfo.applicationInfo.engineVersion = 1;
  createInfo.applicationInfo.apiVersion = XR_API_VERSION_1_0;
 
  strcpy_s(createInfo.applicationInfo.applicationName, applicationName.c_str());
 
  CHECK_XRCMD(xrCreateInstance(&createInfo, m_instanceHandle.Put(xrDestroyInstance)));
 
  xr::g_dispatchTable.Initialize(m_instanceHandle.Get(), xrGetInstanceProcAddr);
}
 
const xr::InstanceHandle& Ogre::OpenXRInstance::getHandle()
{
  return m_instanceHandle;
}
 
const bool Ogre::OpenXRInstance::initialized()
{
  return m_instanceHandle.Get() != XR_NULL_HANDLE;
}
 
std::vector<const char*> SelectExtensions()
{
  // Fetch the list of extensions supported by the runtime.
  uint32_t extensionCount;
  CHECK_XRCMD(xrEnumerateInstanceExtensionProperties(nullptr, 0, &extensionCount, nullptr));
  std::vector<XrExtensionProperties> extensionProperties(extensionCount, { XR_TYPE_EXTENSION_PROPERTIES });
  CHECK_XRCMD(xrEnumerateInstanceExtensionProperties(nullptr, extensionCount, &extensionCount, extensionProperties.data()));
 
  std::vector<const char*> enabledExtensions;
 
  // Add a specific extension to the list of extensions to be enabled, if it is supported.
  auto EnableExtensionIfSupported = [&](const char* extensionName) {
    for (uint32_t i = 0; i < extensionCount; i++) {
      if (strcmp(extensionProperties[i].extensionName, extensionName) == 0) {
        enabledExtensions.push_back(extensionName);
        return true;
      }
    }
    return false;
  };
 
  // D3D11 extension is required for this sample, so check if it's supported.
  CHECK(EnableExtensionIfSupported(XR_KHR_D3D11_ENABLE_EXTENSION_NAME));
 
  return enabledExtensions;
}