07.深度

介绍

在本课程中，我们将通过创建深度/模板缓冲区和视图，然后将其绑定到OM舞台，学习如何隐含3D场景的深度。

深度/模具视图

深度/模板视图的作用是让管线的OM阶段检查渲染目标上所有像素细分的深度/模板值。像素片段是有可能被写入屏幕的像素。想想一个球体和一个盒子。球体位于框的后面，因此当它们通过渲染管线泵送时，来自球体的像素和来自框的像素都被放置到渲染目标上。这些像素称为像素片段。当像素到达OM阶段时，OM阶段会将像素片段深度值与该位置中已经存在的像素片段进行比较。如果新的像素片段深度值小于已经存在的像素片段，则将丢弃已经存在的像素片段，并将新的像素片段保留在渲染目标上。回到球体和盒子。假设先渲染球体。渲染目标上尚无几何图形，因此将渲染整个球体。但是，当盒子的像素到达OM阶段时，OM阶段会比较来自盒子的像素和来自球体的像素的深度值。由于框位于球体的前面，因此将丢弃球体的像素片段，并将框的像素片段保留在渲染目标上。绘制所有几何图形后，渲染目标上剩余的像素就是屏幕上显示的像素。由于框位于球体的前面，因此将丢弃球体的像素片段，并将框的像素片段保留在渲染目标上。绘制所有几何图形后，渲染目标上剩余的像素就是屏幕上显示的像素。由于框位于球体的前面，因此将丢弃球体的像素片段，并将框的像素片段保留在渲染目标上。绘制所有几何图形后，渲染目标上剩余的像素就是屏幕上显示的像素。 深度视图的模具部分用于高级技术，例如镜子，我们将在后面学习。

全球宣言

在这里，我们有两个新的接口对象。一种是存储深度/模板视图，另一种是存储深度/模板缓冲区。

ID3D11DepthStencilView* depthStencilView;
ID3D11Texture2D* depthStencilBuffer;

深度/模板缓冲区说明

现在转到初始化d3d的位置。在创建深度/模板缓冲区之前，我们需要对其进行定义。我们可以通过填充D3D11_TEXTURE2D_DESC来做到这一点，就像填充后台缓冲区一样。由于我们已经介绍了此结构，因此在这里真正需要提及的唯一一件事就是绑定标志和格式。格式为两个变量提供了空间；深度为24位，模板为8位。绑定标志表示此纹理将作为深度/模板缓冲区绑定到OM阶段。

//Describe our Depth/Stencil Buffer
D3D11_TEXTURE2D_DESC depthStencilDesc;

depthStencilDesc.Width     = Width;
depthStencilDesc.Height    = Height;
depthStencilDesc.MipLevels = 1;
depthStencilDesc.ArraySize = 1;
depthStencilDesc.Format    = DXGI_FORMAT_D24_UNORM_S8_UINT;
depthStencilDesc.SampleDesc.Count   = 1;
depthStencilDesc.SampleDesc.Quality = 0;
depthStencilDesc.Usage          = D3D11_USAGE_DEFAULT;
depthStencilDesc.BindFlags      = D3D11_BIND_DEPTH_STENCIL;
depthStencilDesc.CPUAccessFlags = 0; 
depthStencilDesc.MiscFlags      = 0;

创建深度/模具视图

现在我们已经定义了深度/模板缓冲区，我们需要创建它。我们可以使用设备接口的CreateTexture2D方法创建它。创建深度/模板缓冲区后，我们需要创建深度/模板视图，该视图将绑定到管道的OM阶段。我们通过从设备界面调用CreateDepthStencilView（）来实现。第一个参数是我们的深度/模板缓冲区描述，第二个参数用于深度/模板状态。我们没有一个，因此将其设置为NULL。第三个是返回的深度/模板缓冲区。

d3d11Device->CreateTexture2D(&depthStencilDesc, NULL, &depthStencilBuffer);
d3d11Device->CreateDepthStencilView(depthStencilBuffer, NULL, &depthStencilView);

绑定深度/模具视图

在程序中隐含深度的最后一件事是将其绑定到管道的OM阶段。还记得绑定渲染目标时使用的这个功能吗？在调用此函数并将第三个参数设置为NULL之前，因为我们没有深度/模具视图。现在我们有了一个，因此我们可以将该NULL参数更改为我们从上面创建的depthStencilView对象。

d3d11DevCon->OMSetRenderTargets( 1, &renderTargetView, depthStencilView );

向视口添加深度值

转到我们创建和描述视口的位置。我们需要告诉流水线的OM阶段将像素的z值或深度值转换为0到1之间的值，其中0是最可能的值，而1是最远的值。

viewport.MinDepth = 0.0f;
viewport.MaxDepth = 1.0f;

打扫干净

不要忘记释放COM对象！

depthStencilView->Release();
depthStencilBuffer->Release();

清除深度/模具视图

我们需要确保做的最后一件事是清除每帧的深度/模板视图，就像我们对渲染目标视图所做的那样。我们通过调用设备上下文接口的ClearDepthStencilView（）方法来实现。第一个值是我们要清除的深度/模板视图，第二个是枚举类型，或一起使用，指定要清除的深度/模板视图的一部分，第四个参数是我们要清除深度的值。我们将其设置为1.0f，因为1.0f是任何东西都可以拥有的最大深度值。这样可以确保在屏幕上绘制所有对象。如果我们在此处设置0.0f，则不会在屏幕上绘制任何东西，因为像素片段的所有深度值都将在0.0f和1.0f之间。最后一个参数是我们将模板设置为的值。由于未使用它，因此将其设置为0。

d3d11DevCon->ClearDepthStencilView(depthStencilView, D3D11_CLEAR_DEPTH|D3D11_CLEAR_STENCIL, 1.0f, 0);

不太难！

行使：

1.通过创建另一个z值小于我们平方的三角形来测试深度/模具视图。

这是最终代码：

main.cpp

//Include and link appropriate libraries and headers//
#pragma comment(lib, "d3d11.lib")
#pragma comment(lib, "d3dx11.lib")
#pragma comment(lib, "d3dx10.lib")

#include <windows.h>
#include <d3d11.h>
#include <d3dx11.h>
#include <d3dx10.h>
#include <xnamath.h>

//Global Declarations - Interfaces//
IDXGISwapChain* SwapChain;
ID3D11Device* d3d11Device;
ID3D11DeviceContext* d3d11DevCon;
ID3D11RenderTargetView* renderTargetView;
ID3D11Buffer* squareIndexBuffer;
ID3D11Buffer* squareVertBuffer;
///**************new**************
ID3D11DepthStencilView* depthStencilView;
ID3D11Texture2D* depthStencilBuffer;
///**************new**************
ID3D11VertexShader* VS;
ID3D11PixelShader* PS;
ID3D10Blob* VS_Buffer;
ID3D10Blob* PS_Buffer;
ID3D11InputLayout* vertLayout;

//Global Declarations - Others//
LPCTSTR WndClassName = L"firstwindow";
HWND hwnd = NULL;
HRESULT hr;

const int Width  = 300;
const int Height = 300;

//Function Prototypes//
bool InitializeDirect3d11App(HINSTANCE hInstance);
void CleanUp();
bool InitScene();
void UpdateScene();
void DrawScene();

bool InitializeWindow(HINSTANCE hInstance,
    int ShowWnd,
    int width, int height,
    bool windowed);
int messageloop();

LRESULT CALLBACK WndProc(HWND hWnd,
    UINT msg,
    WPARAM wParam,
    LPARAM lParam);

//Vertex Structure and Vertex Layout (Input Layout)//
struct Vertex    //Overloaded Vertex Structure
{
    Vertex(){}
    Vertex(float x, float y, float z,
        float cr, float cg, float cb, float ca)
        : pos(x,y,z), color(cr, cg, cb, ca){}

    XMFLOAT3 pos;
    XMFLOAT4 color;
};

D3D11_INPUT_ELEMENT_DESC layout[] =
{
    { "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D11_INPUT_PER_VERTEX_DATA, 0 },  
    { "COLOR", 0, DXGI_FORMAT_R32G32B32A32_FLOAT, 0, 12, D3D11_INPUT_PER_VERTEX_DATA, 0 },  
};
UINT numElements = ARRAYSIZE(layout);

int WINAPI WinMain(HINSTANCE hInstance,    //Main windows function
    HINSTANCE hPrevInstance, 
    LPSTR lpCmdLine,
    int nShowCmd)
{

    if(!InitializeWindow(hInstance, nShowCmd, Width, Height, true))
    {
        MessageBox(0, L"Window Initialization - Failed",
            L"Error", MB_OK);
        return 0;
    }

    if(!InitializeDirect3d11App(hInstance))    //Initialize Direct3D
    {
        MessageBox(0, L"Direct3D Initialization - Failed",
            L"Error", MB_OK);
        return 0;
    }

    if(!InitScene())    //Initialize our scene
    {
        MessageBox(0, L"Scene Initialization - Failed",
            L"Error", MB_OK);
        return 0;
    }

    messageloop();

    CleanUp();    

    return 0;
}

bool InitializeWindow(HINSTANCE hInstance,
    int ShowWnd,
    int width, int height,
    bool windowed)
{
    typedef struct _WNDCLASS {
        UINT cbSize;
        UINT style;
        WNDPROC lpfnWndProc;
        int cbClsExtra;
        int cbWndExtra;
        HANDLE hInstance;
        HICON hIcon;
        HCURSOR hCursor;
        HBRUSH hbrBackground;
        LPCTSTR lpszMenuName;
        LPCTSTR lpszClassName;
    } WNDCLASS;

    WNDCLASSEX wc;

    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = WndProc;
    wc.cbClsExtra = NULL;
    wc.cbWndExtra = NULL;
    wc.hInstance = hInstance;
    wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 2);
    wc.lpszMenuName = NULL;
    wc.lpszClassName = WndClassName;
    wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);

    if (!RegisterClassEx(&wc))
    {
        MessageBox(NULL, L"Error registering class",    
            L"Error", MB_OK | MB_ICONERROR);
        return 1;
    }

    hwnd = CreateWindowEx(
        NULL,
        WndClassName,
        L"Lesson 4 - Begin Drawing",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT,
        width, height,
        NULL,
        NULL,
        hInstance,
        NULL
        );

    if (!hwnd)
    {
        MessageBox(NULL, L"Error creating window",
            L"Error", MB_OK | MB_ICONERROR);
        return 1;
    }

    ShowWindow(hwnd, ShowWnd);
    UpdateWindow(hwnd);

    return true;
}

bool InitializeDirect3d11App(HINSTANCE hInstance)
{
    //Describe our SwapChain Buffer
    DXGI_MODE_DESC bufferDesc;

    ZeroMemory(&bufferDesc, sizeof(DXGI_MODE_DESC));

    bufferDesc.Width = Width;
    bufferDesc.Height = Height;
    bufferDesc.RefreshRate.Numerator = 60;
    bufferDesc.RefreshRate.Denominator = 1;
    bufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
    bufferDesc.ScanlineOrdering = DXGI_MODE_SCANLINE_ORDER_UNSPECIFIED;
    bufferDesc.Scaling = DXGI_MODE_SCALING_UNSPECIFIED;

    //Describe our SwapChain
    DXGI_SWAP_CHAIN_DESC swapChainDesc; 

    ZeroMemory(&swapChainDesc, sizeof(DXGI_SWAP_CHAIN_DESC));

    swapChainDesc.BufferDesc = bufferDesc;
    swapChainDesc.SampleDesc.Count = 1;
    swapChainDesc.SampleDesc.Quality = 0;
    swapChainDesc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
    swapChainDesc.BufferCount = 1;
    swapChainDesc.OutputWindow = hwnd; 
    swapChainDesc.Windowed = TRUE; 
    swapChainDesc.SwapEffect = DXGI_SWAP_EFFECT_DISCARD;


    //Create our SwapChain
    hr = D3D11CreateDeviceAndSwapChain(NULL, D3D_DRIVER_TYPE_HARDWARE, NULL, NULL, NULL, NULL,
        D3D11_SDK_VERSION, &swapChainDesc, &SwapChain, &d3d11Device, NULL, &d3d11DevCon);

    //Create our BackBuffer
    ID3D11Texture2D* BackBuffer;
    hr = SwapChain->GetBuffer( 0, __uuidof( ID3D11Texture2D ), (void**)&BackBuffer );

    //Create our Render Target
    hr = d3d11Device->CreateRenderTargetView( BackBuffer, NULL, &renderTargetView );
    BackBuffer->Release();

    ///**************new**************
    //Describe our Depth/Stencil Buffer
    D3D11_TEXTURE2D_DESC depthStencilDesc;

    depthStencilDesc.Width     = Width;
    depthStencilDesc.Height    = Height;
    depthStencilDesc.MipLevels = 1;
    depthStencilDesc.ArraySize = 1;
    depthStencilDesc.Format    = DXGI_FORMAT_D24_UNORM_S8_UINT;
    depthStencilDesc.SampleDesc.Count   = 1;
    depthStencilDesc.SampleDesc.Quality = 0;
    depthStencilDesc.Usage          = D3D11_USAGE_DEFAULT;
    depthStencilDesc.BindFlags      = D3D11_BIND_DEPTH_STENCIL;
    depthStencilDesc.CPUAccessFlags = 0; 
    depthStencilDesc.MiscFlags      = 0;

    //Create the Depth/Stencil View
    d3d11Device->CreateTexture2D(&depthStencilDesc, NULL, &depthStencilBuffer);
    d3d11Device->CreateDepthStencilView(depthStencilBuffer, NULL, &depthStencilView);

    //Set our Render Target
    d3d11DevCon->OMSetRenderTargets( 1, &renderTargetView, depthStencilView );
    ///**************new**************

    return true;
}

void CleanUp()
{
    //Release the COM Objects we created
    SwapChain->Release();
    d3d11Device->Release();
    d3d11DevCon->Release();
    renderTargetView->Release();
    squareVertBuffer->Release();
    squareIndexBuffer->Release();
    VS->Release();
    PS->Release();
    VS_Buffer->Release();
    PS_Buffer->Release();
    vertLayout->Release();
    ///**************new**************
    depthStencilView->Release();
    depthStencilBuffer->Release();
    ///**************new**************
}

bool InitScene()
{
    //Compile Shaders from shader file
    hr = D3DX11CompileFromFile(L"Effects.fx", 0, 0, "VS", "vs_4_0", 0, 0, 0, &VS_Buffer, 0, 0);
    hr = D3DX11CompileFromFile(L"Effects.fx", 0, 0, "PS", "ps_4_0", 0, 0, 0, &PS_Buffer, 0, 0);

    //Create the Shader Objects
    hr = d3d11Device->CreateVertexShader(VS_Buffer->GetBufferPointer(), VS_Buffer->GetBufferSize(), NULL, &VS);
    hr = d3d11Device->CreatePixelShader(PS_Buffer->GetBufferPointer(), PS_Buffer->GetBufferSize(), NULL, &PS);

    //Set Vertex and Pixel Shaders
    d3d11DevCon->VSSetShader(VS, 0, 0);
    d3d11DevCon->PSSetShader(PS, 0, 0);

    //Create the vertex buffer
    Vertex v[] =
    {
        Vertex( -0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 1.0f ),
        Vertex( -0.5f,  0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f ),
        Vertex(  0.5f,  0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f ),
        Vertex(  0.5f, -0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f ),
    };

    DWORD indices[] = {
        0, 1, 2,
        0, 2, 3,
    };

    D3D11_BUFFER_DESC indexBufferDesc;
    ZeroMemory( &indexBufferDesc, sizeof(indexBufferDesc) );

    indexBufferDesc.Usage = D3D11_USAGE_DEFAULT;
    indexBufferDesc.ByteWidth = sizeof(DWORD) * 2 * 3;
    indexBufferDesc.BindFlags = D3D11_BIND_INDEX_BUFFER;
    indexBufferDesc.CPUAccessFlags = 0;
    indexBufferDesc.MiscFlags = 0;

    D3D11_SUBRESOURCE_DATA iinitData;

    iinitData.pSysMem = indices;
    d3d11Device->CreateBuffer(&indexBufferDesc, &iinitData, &squareIndexBuffer);

    d3d11DevCon->IASetIndexBuffer( squareIndexBuffer, DXGI_FORMAT_R32_UINT, 0);


    D3D11_BUFFER_DESC vertexBufferDesc;
    ZeroMemory( &vertexBufferDesc, sizeof(vertexBufferDesc) );

    vertexBufferDesc.Usage = D3D11_USAGE_DEFAULT;
    vertexBufferDesc.ByteWidth = sizeof( Vertex ) * 4;
    vertexBufferDesc.BindFlags = D3D11_BIND_VERTEX_BUFFER;
    vertexBufferDesc.CPUAccessFlags = 0;
    vertexBufferDesc.MiscFlags = 0;

    D3D11_SUBRESOURCE_DATA vertexBufferData; 

    ZeroMemory( &vertexBufferData, sizeof(vertexBufferData) );
    vertexBufferData.pSysMem = v;
    hr = d3d11Device->CreateBuffer( &vertexBufferDesc, &vertexBufferData, &squareVertBuffer);

    //Set the vertex buffer
    UINT stride = sizeof( Vertex );
    UINT offset = 0;
    d3d11DevCon->IASetVertexBuffers( 0, 1, &squareVertBuffer, &stride, &offset );

    //Create the Input Layout
    hr = d3d11Device->CreateInputLayout( layout, numElements, VS_Buffer->GetBufferPointer(), 
        VS_Buffer->GetBufferSize(), &vertLayout );

    //Set the Input Layout
    d3d11DevCon->IASetInputLayout( vertLayout );

    //Set Primitive Topology
    d3d11DevCon->IASetPrimitiveTopology( D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST );

    //Create the Viewport
    D3D11_VIEWPORT viewport;
    ZeroMemory(&viewport, sizeof(D3D11_VIEWPORT));

    viewport.TopLeftX = 0;
    viewport.TopLeftY = 0;
    viewport.Width = Width;
    viewport.Height = Height;
    ///**************new**************
    viewport.MinDepth = 0.0f;
    viewport.MaxDepth = 1.0f;
    ///**************new**************

    //Set the Viewport
    d3d11DevCon->RSSetViewports(1, &viewport);

    return true;
}

void UpdateScene()
{

}

void DrawScene()
{
    //Clear our backbuffer
    float bgColor[4] = {(0.0f, 0.0f, 0.0f, 0.0f)};
    d3d11DevCon->ClearRenderTargetView(renderTargetView, bgColor);

    ///**************new**************
    //Refresh the Depth/Stencil view
    d3d11DevCon->ClearDepthStencilView(depthStencilView, D3D11_CLEAR_DEPTH|D3D11_CLEAR_STENCIL, 1.0f, 0);
    ///**************new**************

    //Draw the triangle
    d3d11DevCon->DrawIndexed( 6, 0, 0 );

    //Present the backbuffer to the screen
    SwapChain->Present(0, 0);
}

int messageloop(){
    MSG msg;
    ZeroMemory(&msg, sizeof(MSG));
    while(true)
    {
        BOOL PeekMessageL( 
            LPMSG lpMsg,
            HWND hWnd,
            UINT wMsgFilterMin,
            UINT wMsgFilterMax,
            UINT wRemoveMsg
            );

        if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
        {
            if (msg.message == WM_QUIT)
                break;
            TranslateMessage(&msg);    
            DispatchMessage(&msg);
        }
        else{
            // run game code            
            UpdateScene();
            DrawScene();
        }
    }
    return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd,
    UINT msg,
    WPARAM wParam,
    LPARAM lParam)
{
    switch( msg )
    {
    case WM_KEYDOWN:
        if( wParam == VK_ESCAPE ){
            DestroyWindow(hwnd);
        }
        return 0;

    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }
    return DefWindowProc(hwnd,
        msg,
        wParam,
        lParam);
}

Effects.fx：

struct VS_OUTPUT
{
    float4 Pos : SV_POSITION;
    float4 Color : COLOR;
};

VS_OUTPUT VS(float4 inPos : POSITION, float4 inColor : COLOR)
{
    VS_OUTPUT output;

    output.Pos = inPos;
    output.Color = inColor;

    return output;
}

float4 PS(VS_OUTPUT input) : SV_TARGET
{
    return input.Color;
}