分四个大阶段：初始化（initialize），加载(load)，渲染(render)，销毁(release)。
一.初始化
初始化DX11设备(DIRECTX.InitDevice)，分以下几步：
1.创建DXGI(DirectX Graphics Infrastructure)对象，枚举系统中的显卡设备。其中DXGI是直接与硬件打交道的，它是Windows系统中用户模式下最底层的图形设备接口，Direct3D是基于其上的。（DXGI（DirectX Graphics Inf rastructure）是独立于Direct3D的API，用于处理与图形关联的东西，例如交换链（帧缓冲）等。DXGI与Direct3D分离的目的在于其他图形API（例如Direct2D）也需要交换链、图形硬件枚举、在窗口和全屏模式之间切换，通过这种设计，多个图形API都能使用DXGI API。）
IDXGIAdapter * Adapter = nullptr;
for (UINT iAdapter = 0; DXGIFactory->EnumAdapters(iAdapter, &Adapter) != DXGI_ERROR_NOT_FOUND; ++iAdapter)
{
DXGI_ADAPTER_DESC adapterDesc;
Adapter->GetDesc(&adapterDesc);
if ((pLuid == nullptr) || memcmp(&adapterDesc.AdapterLuid, pLuid, sizeof(LUID)) == 0)
break;
Release(Adapter);
}2.创建D3D11设备及其上下文，通过1中获取到的显卡及其驱动类型以及D3D SDK版本创建一个D3D设备以及它的context。
auto DriverType = Adapter ? D3D_DRIVER_TYPE_UNKNOWN : D3D_DRIVER_TYPE_HARDWARE;
hr = D3D11CreateDevice(Adapter, DriverType, 0, 0, 0, 0, D3D11_SDK_VERSION, &Device, 0, &Context);3.创建DXGI后台交换链帧缓冲（可与opengl类比理解）。设置后台交换链帧缓冲区个数（BufferCount），高宽尺寸，格式，刷新率（是否开启垂直同步定），将场景渲染到后台缓冲区，输出窗口句柄。
// Create swap chain
DXGI_SWAP_CHAIN_DESC scDesc;
memset(&scDesc, 0, sizeof(scDesc));
scDesc.BufferCount = 2;
scDesc.BufferDesc.Width = WinSizeW;
scDesc.BufferDesc.Height = WinSizeH;
scDesc.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
scDesc.BufferDesc.RefreshRate.Denominator = 1;
scDesc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
scDesc.OutputWindow = Window;
scDesc.SampleDesc.Count = 1;
scDesc.Windowed = windowed;
scDesc.SwapEffect = DXGI_SWAP_EFFECT_SEQUENTIAL;
hr = DXGIFactory->CreateSwapChain(Device, &scDesc, &SwapChain);
Release(DXGIFactory);
VALIDATE((hr == ERROR_SUCCESS), "CreateSwapChain failed");4.创建渲染目标视图，通过GetBuffer获取一个交换链的后台帧缓冲指针，第一个参数表示要获取的后台帧缓冲区的索引值为0，第二个参数表示缓冲区的类型，第三个参数返回指向后台缓冲区的指针；通过CreateRenderTargetView创建渲染目标视图，第一个参数表示将要作为渲染目标的资源，第二个参数为NULL，表示以资源的第一个mipmap层次作为视图的格式。第三个参数返回创建后的渲染目标视图对象。
// Create backbuffer
SwapChain->GetBuffer(0, __uuidof(ID3D11Texture2D), (void**)&BackBuffer);
hr = Device->CreateRenderTargetView(BackBuffer, NULL, &BackBufferRT);
VALIDATE((hr == ERROR_SUCCESS), "CreateRenderTargetView failed");5.创建深度模板缓冲区及其视图，且将视图绑定到输出混合器
MainDepthBuffer = new DepthBuffer(Device, WinSizeW, WinSizeH);
Context->OMSetRenderTargets(1, &BackBufferRT, MainDepthBuffer->TexDsv);
//------------------
DepthBuffer(ID3D11Device * Device, int sizeW, int sizeH, int sampleCount = 1)
{
DXGI_FORMAT format = DXGI_FORMAT_D32_FLOAT;
D3D11_TEXTURE2D_DESC dsDesc;
dsDesc.Width = sizeW;
dsDesc.Height = sizeH;
dsDesc.MipLevels = 1;
dsDesc.ArraySize = 1;
dsDesc.Format = format;
dsDesc.SampleDesc.Count = sampleCount;
dsDesc.SampleDesc.Quality = 0;
dsDesc.Usage = D3D11_USAGE_DEFAULT;
dsDesc.CPUAccessFlags = 0;
dsDesc.MiscFlags = 0;
dsDesc.BindFlags = D3D11_BIND_DEPTH_STENCIL;
ID3D11Texture2D * Tex;
Device->CreateTexture2D(&dsDesc, NULL, &Tex);
Device->CreateDepthStencilView(Tex, NULL, &TexDsv);
}6.创建数据常量缓冲，用于存放顶点数据资源。
// Buffer for shader constants
UniformBufferGen = new DataBuffer(Device, D3D11_BIND_CONSTANT_BUFFER, NULL, UNIFORM_DATA_SIZE);
Context->VSSetConstantBuffers(0, 1, &UniformBufferGen->D3DBuffer);7.设置最大帧延迟为1，也就是允许等待渲染的帧的最大数量。
// Set max frame latency to 1
IDXGIDevice1* DXGIDevice1 = nullptr;
hr = Device->QueryInterface(__uuidof(IDXGIDevice1), (void**)&DXGIDevice1);
DXGIDevice1->SetMaximumFrameLatency(1);
Release(DXGIDevice1);
VALIDATE((hr == ERROR_SUCCESS), "QueryInterface failed");
ovr_Create创建HMD设备以及获取设备所关联的显卡luid，ovr_GetHmdDesc获取设备的分辨率以及双眼默认的视场角，DIRECTX.InitDevice配置与设备相关的显卡以及创建D3D11设备（D3D11CreateDevice），创建与设备相关2D纹理交换链（DXGIFactory->CreateSwapChain），后缓冲（Device->CreateRenderTargetView），主深度缓冲Device->CreateTexture2D(&dsDesc, NULL, &Tex);Device->CreateDepthStencilView(Tex, NULL, &TexDsv);，着色器数据常量缓冲(Device->CreateBuffer(&desc, buffer ? &sr : NULL, &D3DBuffer);)以及最大帧延迟(DXGIDevice1->SetMaximumFrameLatency(1);)。
二.加载：
加载场景资源
1.获取视场角纹理尺寸大小，创建纹理交换链集，并为每个纹理创建一个渲染目标视图。并为纹理创建相对应的深度缓冲，再将其大小赋给眼部渲染视口。
{
ovrSizei idealSize = ovr_GetFovTextureSize(HMD, (ovrEyeType)eye, hmdDesc.DefaultEyeFov[eye], 1.0f);
pEyeRenderTexture[eye] = new OculusTexture();
if (!pEyeRenderTexture[eye]->Init(HMD, idealSize.w, idealSize.h))
{
if (retryCreate) goto Done;
VALIDATE(OVR_SUCCESS(result), "Failed to create eye texture.");
}
pEyeDepthBuffer[eye] = new DepthBuffer(DIRECTX.Device, idealSize.w, idealSize.h);
eyeRenderViewport[eye].Pos.x = 0;
eyeRenderViewport[eye].Pos.y = 0;
eyeRenderViewport[eye].Size = idealSize;
if (!pEyeRenderTexture[eye]->TextureSet)
{
if (retryCreate) goto Done;
VALIDATE(false, "Failed to create texture.");
}
}
其中OculusTexture类中初始化时，创建了交换链纹理集：
bool Init(ovrHmd _hmd, int sizeW, int sizeH)
{
hmd = _hmd;
D3D11_TEXTURE2D_DESC dsDesc;
dsDesc.Width = sizeW;
dsDesc.Height = sizeH;
dsDesc.MipLevels = 1;
dsDesc.ArraySize = 1;
dsDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM_SRGB;
dsDesc.SampleDesc.Count = 1; // No multi-sampling allowed
dsDesc.SampleDesc.Quality = 0;
dsDesc.Usage = D3D11_USAGE_DEFAULT;
dsDesc.CPUAccessFlags = 0;
dsDesc.MiscFlags = 0;
dsDesc.BindFlags = D3D11_BIND_SHADER_RESOURCE | D3D11_BIND_RENDER_TARGET;
ovrResult result = ovr_CreateSwapTextureSetD3D11(hmd, DIRECTX.Device, &dsDesc, ovrSwapTextureSetD3D11_Typeless, &TextureSet);
if (!OVR_SUCCESS(result))
return false;
VALIDATE(TextureSet->TextureCount == TextureCount, "TextureCount mismatch.");
for (int i = 0; i < TextureCount; ++i)
{
ovrD3D11Texture* tex = (ovrD3D11Texture*)&TextureSet->Textures[i];
D3D11_RENDER_TARGET_VIEW_DESC rtvd = {};
rtvd.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
rtvd.ViewDimension = D3D11_RTV_DIMENSION_TEXTURE2D;
DIRECTX.Device->CreateRenderTargetView(tex->D3D11.pTexture, &rtvd, &TexRtv[i]);
}
return true;
}2.在屏幕上显示创建镜像纹理
// Create a mirror to see on the monitor.
td.ArraySize = 1;
td.Format = DXGI_FORMAT_R8G8B8A8_UNORM_SRGB;
td.Width = DIRECTX.WinSizeW;
td.Height = DIRECTX.WinSizeH;
td.Usage = D3D11_USAGE_DEFAULT;
td.SampleDesc.Count = 1;
td.MipLevels = 1;
result = ovr_CreateMirrorTextureD3D11(HMD, DIRECTX.Device, &td, 0, &mirrorTexture);3.创建场景模型
// Create the room model
roomScene = new Scene(false);
void Init(bool includeIntensiveGPUobject)
{
TriangleSet cube;
cube.AddSolidColorBox(0.5f, -0.5f, 0.5f, -0.5f, 0.5f, -0.5f, 0xff404040);
Add(
new Model(&cube, XMFLOAT3(0, 0, 0), XMFLOAT4(0, 0, 0, 1),
new Material(
new Texture(false, 256, 256, Texture::AUTO_CEILING)
)
)
);
TriangleSet spareCube;
spareCube.AddSolidColorBox(0.1f, -0.1f, 0.1f, -0.1f, +0.1f, -0.1f, 0xffff0000);
Add(
new Model(&spareCube, XMFLOAT3(0, -10, 0), XMFLOAT4(0, 0, 0, 1),
new Material(
new Texture(false, 256, 256, Texture::AUTO_CEILING)
)
)
);
TriangleSet walls;
walls.AddSolidColorBox(10.1f, 0.0f, 20.0f, 10.0f, 4.0f, -20.0f, 0xff808080); // Left Wall
walls.AddSolidColorBox(10.0f, -0.1f, 20.1f, -10.0f, 4.0f, 20.0f, 0xff808080); // Back Wall
walls.AddSolidColorBox(-10.0f, -0.1f, 20.0f, -10.1f, 4.0f, -20.0f, 0xff808080); // Right Wall
Add(
new Model(&walls, XMFLOAT3(0, 0, 0), XMFLOAT4(0, 0, 0, 1),
new Material(
new Texture(false, 256, 256, Texture::AUTO_WALL)
)
)
);
if (includeIntensiveGPUobject)
{
TriangleSet partitions;
for (float depth = 0.0f; depth > -3.0f; depth -= 0.1f)
partitions.AddSolidColorBox(9.0f, 0.5f, -depth, -9.0f, 3.5f, -depth, 0x10ff80ff); // Partition
Add(
new Model(&partitions, XMFLOAT3(0, 0, 0), XMFLOAT4(0, 0, 0, 1),
new Material(
new Texture(false, 256, 256, Texture::AUTO_FLOOR)
)
)
); // Floors
}
TriangleSet floors;
floors.AddSolidColorBox(10.0f, -0.1f, 20.0f, -10.0f, 0.0f, -20.1f, 0xff808080); // Main floor
floors.AddSolidColorBox(15.0f, -6.1f, -18.0f, -15.0f, -6.0f, -30.0f, 0xff808080); // Bottom floor
Add(
new Model(&floors, XMFLOAT3(0, 0, 0), XMFLOAT4(0, 0, 0, 1),
new Material(
new Texture(false, 256, 256, Texture::AUTO_FLOOR)
)
)
); // Floors
TriangleSet ceiling;
ceiling.AddSolidColorBox(10.0f, 4.0f, 20.0f, -10.0f, 4.1f, -20.1f, 0xff808080);
Add(
new Model(&ceiling, XMFLOAT3(0, 0, 0), XMFLOAT4(0, 0, 0, 1),
new Material(
new Texture(false, 256, 256, Texture::AUTO_CEILING)
)
)
); // Ceiling
TriangleSet furniture;
furniture.AddSolidColorBox(-9.5f, 0.75f, -3.0f, -10.1f, 2.5f, -3.1f, 0xff383838); // Right side shelf// Verticals
furniture.AddSolidColorBox(-9.5f, 0.95f, -3.7f, -10.1f, 2.75f, -3.8f, 0xff383838); // Right side shelf
furniture.AddSolidColorBox(-9.55f, 1.20f, -2.5f, -10.1f, 1.30f, -3.75f, 0xff383838); // Right side shelf// Horizontals
furniture.AddSolidColorBox(-9.55f, 2.00f, -3.05f, -10.1f, 2.10f, -4.2f, 0xff383838); // Right side shelf
furniture.AddSolidColorBox(-5.0f, 1.1f, -20.0f, -10.0f, 1.2f, -20.1f, 0xff383838); // Right railing
furniture.AddSolidColorBox(10.0f, 1.1f, -20.0f, 5.0f, 1.2f, -20.1f, 0xff383838); // Left railing
for (float f = 5; f <= 9; f += 1)
furniture.AddSolidColorBox(-f, 0.0f, -20.0f, -f - 0.1f, 1.1f, -20.1f, 0xff505050); // Left Bars
for (float f = 5; f <= 9; f += 1)
furniture.AddSolidColorBox(f, 1.1f, -20.0f, f + 0.1f, 0.0f, -20.1f, 0xff505050); // Right Bars
furniture.AddSolidColorBox(1.8f, 0.8f, -1.0f, 0.0f, 0.7f, 0.0f, 0xff505000); // Table
furniture.AddSolidColorBox(1.8f, 0.0f, 0.0f, 1.7f, 0.7f, -0.1f, 0xff505000); // Table Leg
furniture.AddSolidColorBox(1.8f, 0.7f, -1.0f, 1.7f, 0.0f, -0.9f, 0xff505000); // Table Leg
furniture.AddSolidColorBox(0.0f, 0.0f, -1.0f, 0.1f, 0.7f, -0.9f, 0xff505000); // Table Leg
furniture.AddSolidColorBox(0.0f, 0.7f, 0.0f, 0.1f, 0.0f, -0.1f, 0xff505000); // Table Leg
furniture.AddSolidColorBox(1.4f, 0.5f, 1.1f, 0.8f, 0.55f, 0.5f, 0xff202050); // Chair Set
furniture.AddSolidColorBox(1.401f, 0.0f, 1.101f, 1.339f, 1.0f, 1.039f, 0xff202050); // Chair Leg 1
furniture.AddSolidColorBox(1.401f, 0.5f, 0.499f, 1.339f, 0.0f, 0.561f, 0xff202050); // Chair Leg 2
furniture.AddSolidColorBox(0.799f, 0.0f, 0.499f, 0.861f, 0.5f, 0.561f, 0xff202050); // Chair Leg 2
furniture.AddSolidColorBox(0.799f, 1.0f, 1.101f, 0.861f, 0.0f, 1.039f, 0xff202050); // Chair Leg 2
furniture.AddSolidColorBox(1.4f, 0.97f, 1.05f, 0.8f, 0.92f, 1.10f, 0xff202050); // Chair Back high bar
for (float f = 3.0f; f <= 6.6f; f += 0.4f)
furniture.AddSolidColorBox(3, 0.0f, -f, 2.9f, 1.3f, -f - 0.1f, 0xff404040); // Posts
Add(
new Model(&furniture, XMFLOAT3(0, 0, 0), XMFLOAT4(0, 0, 0, 1),
new Material(
new Texture(false, 256, 256, Texture::AUTO_WHITE)
)
)
); // Fixtures & furniture
}
Scene() : numModels(0) {}
Scene(bool includeIntensiveGPUobject) :
numModels(0)
{
Init(includeIntensiveGPUobject);}4.创建摄像头
// Create camera
__pragma(warning(push))
__pragma(warning(disable:4316)) // Win32: object allocated on the heap may not be aligned 16
mainCam = new Camera(&XMVectorSet(0.0f, 1.6f, 5.0f, 0), &XMQuaternionIdentity());
__pragma(warning(pop))
5.配置VR组件，填充渲染描述符
// Setup VR components, filling out description
ovrEyeRenderDesc eyeRenderDesc[2];
eyeRenderDesc[0] = ovr_GetRenderDesc(HMD, ovrEye_Left, hmdDesc.DefaultEyeFov[0]);
eyeRenderDesc[1] = ovr_GetRenderDesc(HMD, ovrEye_Right, hmdDesc.DefaultEyeFov[1]);三，渲染：
1.在主循环内，使用键盘按键控制摄像头位移旋转：
XMVECTOR forward = XMVector3Rotate(XMVectorSet(0, 0, -0.05f, 0), mainCam->Rot);
XMVECTOR right = XMVector3Rotate(XMVectorSet(0.05f, 0, 0, 0), mainCam->Rot);
if (DIRECTX.Key['W'] || DIRECTX.Key[VK_UP]) mainCam->Pos = XMVectorAdd(mainCam->Pos, forward);
if (DIRECTX.Key['S'] || DIRECTX.Key[VK_DOWN]) mainCam->Pos = XMVectorSubtract(mainCam->Pos, forward);
if (DIRECTX.Key['D']) mainCam->Pos = XMVectorAdd(mainCam->Pos, right);
if (DIRECTX.Key['A']) mainCam->Pos = XMVectorSubtract(mainCam->Pos, right);
static float Yaw = 0;
if (DIRECTX.Key[VK_LEFT]) mainCam->Rot = XMQuaternionRotationRollPitchYaw(0, Yaw += 0.02f, 0);
if (DIRECTX.Key[VK_RIGHT]) mainCam->Rot = XMQuaternionRotationRollPitchYaw(0, Yaw -= 0.02f, 0);
2.获取眼睛姿态信息
ovrPosef EyeRenderPose[2];
ovrVector3f HmdToEyeViewOffset[2] = { eyeRenderDesc[0].HmdToEyeViewOffset,
eyeRenderDesc[1].HmdToEyeViewOffset };
ovrFrameTiming ftiming = ovr_GetFrameTiming(HMD, 0);
ovrTrackingState hmdState = ovr_GetTrackingState(HMD, ftiming.DisplayMidpointSeconds);
ovr_CalcEyePoses(hmdState.HeadPose.ThePose, HmdToEyeViewOffset, EyeRenderPose);
3.渲染场景到眼睛缓冲中
{
// Increment to use next texture, just before writing
pEyeRenderTexture[eye]->AdvanceToNextTexture();
// Clear and set up rendertarget
int texIndex = pEyeRenderTexture[eye]->TextureSet->CurrentIndex;
DIRECTX.SetAndClearRenderTarget(pEyeRenderTexture[eye]->TexRtv[texIndex], pEyeDepthBuffer[eye]);
DIRECTX.SetViewport((float)eyeRenderViewport[eye].Pos.x, (float)eyeRenderViewport[eye].Pos.y,
(float)eyeRenderViewport[eye].Size.w, (float)eyeRenderViewport[eye].Size.h);
//Get the pose information in XM format
XMVECTOR eyeQuat = XMVectorSet(EyeRenderPose[eye].Orientation.x, EyeRenderPose[eye].Orientation.y,
EyeRenderPose[eye].Orientation.z, EyeRenderPose[eye].Orientation.w);
XMVECTOR eyePos = XMVectorSet(EyeRenderPose[eye].Position.x, EyeRenderPose[eye].Position.y, EyeRenderPose[eye].Position.z, 0);
// Get view and projection matrices for the Rift camera
XMVECTOR CombinedPos = XMVectorAdd(mainCam->Pos, XMVector3Rotate(eyePos, mainCam->Rot));
Camera finalCam(&CombinedPos, &(XMQuaternionMultiply(eyeQuat,mainCam->Rot)));
XMMATRIX view = finalCam.GetViewMatrix();
ovrMatrix4f p = ovrMatrix4f_Projection(eyeRenderDesc[eye].Fov, 0.2f, 1000.0f, ovrProjection_RightHanded);
XMMATRIX proj = XMMatrixSet(p.M[0][0], p.M[1][0], p.M[2][0], p.M[3][0],
p.M[0][1], p.M[1][1], p.M[2][1], p.M[3][1],
p.M[0][2], p.M[1][2], p.M[2][2], p.M[3][2],
p.M[0][3], p.M[1][3], p.M[2][3], p.M[3][3]);
XMMATRIX prod = XMMatrixMultiply(view, proj);
roomScene->Render(&prod, 1, 1, 1, 1, true);
}4.初始化单个全屏Fov层，并提交
// Initialize our single full screen Fov layer.
ovrLayerEyeFov ld;
ld.Header.Type = ovrLayerType_EyeFov;
ld.Header.Flags = 0;
for (int eye = 0; eye < 2; ++eye)
{
ld.ColorTexture[eye] = pEyeRenderTexture[eye]->TextureSet;
ld.Viewport[eye] = eyeRenderViewport[eye];
ld.Fov[eye] = hmdDesc.DefaultEyeFov[eye];
ld.RenderPose[eye] = EyeRenderPose[eye];
}
ovrLayerHeader* layers = &ld.Header;
result = ovr_SubmitFrame(HMD, 0, nullptr, &layers, 1);
5.渲染镜像
ovrD3D11Texture* tex = (ovrD3D11Texture*)mirrorTexture;
DIRECTX.Context->CopyResource(DIRECTX.BackBuffer, tex->D3D11.pTexture);
DIRECTX.SwapChain->Present(0, 0);
四，销毁：
delete mainCam;
delete roomScene;
if (mirrorTexture) ovr_DestroyMirrorTexture(HMD, mirrorTexture);
for (int eye = 0; eye < 2; ++eye)
{
delete pEyeRenderTexture[eye];
delete pEyeDepthBuffer[eye];
}
DIRECTX.ReleaseDevice();
ovr_Destroy(HMD);因篇幅问题不能全部显示，请点此查看更多更全内容