DirectX11 颜色立方体示例Demo

颜色立方体示例Demo

1. 核心代码

我们已经讲解了足够多的内容，现在我们可以开始编写一个简单的颜色立方体演示程序了。这个例子基本上包含了我们前面讲到的所有内容。读者应该对照前面的几节，仔细研究这些代码，直到把每一行代码都弄懂为止。
核心代码（建议下载Demo在VS看会更方便，DX11龙书官网有项目源代码下载，请读者自行下载）：

//***************************************************************************************
// BoxDemo.cpp by Frank Luna (C) 2011 All Rights Reserved.
//
// Demonstrates rendering a colored box.
//
// Controls:
//      Hold the left mouse button down and move the mouse to rotate.
//      Hold the right mouse button down to zoom in and out.
//
//***************************************************************************************

#include "d3dApp.h"
#include "d3dx11Effect.h"
#include "MathHelper.h"

struct Vertex
{
    XMFLOAT3 Pos;
    XMFLOAT4 Color;
};

class BoxApp : public D3DApp
{
public:
    BoxApp(HINSTANCE hInstance);
    ~BoxApp();

    bool Init();
    void OnResize();
    void UpdateScene(float dt);
    void DrawScene();

    void OnMouseDown(WPARAM btnState, int x, int y);
    void OnMouseUp(WPARAM btnState, int x, int y);
    void OnMouseMove(WPARAM btnState, int x, int y);

private:
    void BuildGeometryBuffers();
    void BuildFX();
    void BuildVertexLayout();

private:
    ID3D11Buffer* mBoxVB;
    ID3D11Buffer* mBoxIB;

    ID3DX11Effect* mFX;
    ID3DX11EffectTechnique* mTech;
    ID3DX11EffectMatrixVariable* mfxWorldViewProj;

    ID3D11InputLayout* mInputLayout;

    XMFLOAT4X4 mWorld;
    XMFLOAT4X4 mView;
    XMFLOAT4X4 mProj;

    float mTheta;
    float mPhi;
    float mRadius;

    POINT mLastMousePos;
};

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE prevInstance,
                   PSTR cmdLine, int showCmd)
{
    // Enable run-time memory check for debug builds.
#if defined(DEBUG) | defined(_DEBUG)
    _CrtSetDbgFlag( _CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF );
#endif

    BoxApp theApp(hInstance);

    if( !theApp.Init() )
        return 0;

    return theApp.Run();
}


BoxApp::BoxApp(HINSTANCE hInstance)
: D3DApp(hInstance), mBoxVB(0), mBoxIB(0), mFX(0), mTech(0),
  mfxWorldViewProj(0), mInputLayout(0),
  mTheta(1.5f*MathHelper::Pi), mPhi(0.25f*MathHelper::Pi), mRadius(5.0f)
{
    mMainWndCaption = L"Box Demo";

    mLastMousePos.x = 0;
    mLastMousePos.y = 0;

    XMMATRIX I = XMMatrixIdentity();
    XMStoreFloat4x4(&mWorld, I);
    XMStoreFloat4x4(&mView, I);
    XMStoreFloat4x4(&mProj, I);
}

BoxApp::~BoxApp()
{
    ReleaseCOM(mBoxVB);
    ReleaseCOM(mBoxIB);
    ReleaseCOM(mFX);
    ReleaseCOM(mInputLayout);
}

bool BoxApp::Init()
{
    if(!D3DApp::Init())
        return false;

    BuildGeometryBuffers();
    BuildFX();
    BuildVertexLayout();

    return true;
}

void BoxApp::OnResize()
{
    D3DApp::OnResize();

    // 当窗口大小改变时，需要更新横纵比，并重新计算投影矩阵
    XMMATRIX P = XMMatrixPerspectiveFovLH(0.25f*MathHelper::Pi, AspectRatio(), 1.0f, 1000.0f);
    XMStoreFloat4x4(&mProj, P);
}

void BoxApp::UpdateScene(float dt)
{
    // Convert Spherical to Cartesian coordinates.
    float x = mRadius*sinf(mPhi)*cosf(mTheta);
    float z = mRadius*sinf(mPhi)*sinf(mTheta);
    float y = mRadius*cosf(mPhi);

    // 创建视矩阵
    XMVECTOR pos    = XMVectorSet(x, y, z, 1.0f);
    XMVECTOR target = XMVectorZero();
    XMVECTOR up     = XMVectorSet(0.0f, 1.0f, 0.0f, 0.0f);

    XMMATRIX V = XMMatrixLookAtLH(pos, target, up);
    XMStoreFloat4x4(&mView, V);
}

void BoxApp::DrawScene()
{
    md3dImmediateContext->ClearRenderTargetView(mRenderTargetView, reinterpret_cast<const float*>(&Colors::LightSteelBlue));
    md3dImmediateContext->ClearDepthStencilView(mDepthStencilView, D3D11_CLEAR_DEPTH|D3D11_CLEAR_STENCIL, 1.0f, 0);

    md3dImmediateContext->IASetInputLayout(mInputLayout);
    md3dImmediateContext->IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST);

    UINT stride = sizeof(Vertex);
    UINT offset = 0;
    md3dImmediateContext->IASetVertexBuffers(0, 1, &mBoxVB, &stride, &offset);
    md3dImmediateContext->IASetIndexBuffer(mBoxIB, DXGI_FORMAT_R32_UINT, 0);

    // Set constants
    XMMATRIX world = XMLoadFloat4x4(&mWorld);
    XMMATRIX view  = XMLoadFloat4x4(&mView);
    XMMATRIX proj  = XMLoadFloat4x4(&mProj);
    XMMATRIX worldViewProj = world*view*proj;

    mfxWorldViewProj->SetMatrix(reinterpret_cast<float*>(&worldViewProj));

    D3DX11_TECHNIQUE_DESC techDesc;
    mTech->GetDesc( &techDesc );
    for(UINT p = 0; p < techDesc.Passes; ++p)
    {
        mTech->GetPassByIndex(p)->Apply(0, md3dImmediateContext);

        // 立方体有36个索引
        md3dImmediateContext->DrawIndexed(36, 0, 0);
    }

    HR(mSwapChain->Present(0, 0));
}

void BoxApp::OnMouseDown(WPARAM btnState, int x, int y)
{
    mLastMousePos.x = x;
    mLastMousePos.y = y;

    SetCapture(mhMainWnd);
}

void BoxApp::OnMouseUp(WPARAM btnState, int x, int y)
{
    ReleaseCapture();
}

void BoxApp::OnMouseMove(WPARAM btnState, int x, int y)
{
    if( (btnState & MK_LBUTTON) != 0 )
    {
        // Make each pixel correspond to a quarter of a degree.
        float dx = XMConvertToRadians(0.25f*static_cast<float>(x - mLastMousePos.x));
        float dy = XMConvertToRadians(0.25f*static_cast<float>(y - mLastMousePos.y));

        // Update angles based on input to orbit camera around box.
        mTheta += dx;
        mPhi   += dy;

        // Restrict the angle mPhi.
        mPhi = MathHelper::Clamp(mPhi, 0.1f, MathHelper::Pi-0.1f);
    }
    else if( (btnState & MK_RBUTTON) != 0 )
    {
        // Make each pixel correspond to 0.005 unit in the scene.
        float dx = 0.005f*static_cast<float>(x - mLastMousePos.x);
        float dy = 0.005f*static_cast<float>(y - mLastMousePos.y);

        // Update the camera radius based on input.
        mRadius += dx - dy;

        // Restrict the radius.
        mRadius = MathHelper::Clamp(mRadius, 3.0f, 15.0f);
    }

    mLastMousePos.x = x;
    mLastMousePos.y = y;
}

void BoxApp::BuildGeometryBuffers()
{
    // 创建顶点缓冲
    Vertex vertices[] =
    {
        { XMFLOAT3(-1.0f, -1.0f, -1.0f), (const float*)&Colors::White   },
        { XMFLOAT3(-1.0f, +1.0f, -1.0f), (const float*)&Colors::Black   },
        { XMFLOAT3(+1.0f, +1.0f, -1.0f), (const float*)&Colors::Red     },
        { XMFLOAT3(+1.0f, -1.0f, -1.0f), (const float*)&Colors::Green   },
        { XMFLOAT3(-1.0f, -1.0f, +1.0f), (const float*)&Colors::Blue    },
        { XMFLOAT3(-1.0f, +1.0f, +1.0f), (const float*)&Colors::Yellow  },
        { XMFLOAT3(+1.0f, +1.0f, +1.0f), (const float*)&Colors::Cyan    },
        { XMFLOAT3(+1.0f, -1.0f, +1.0f), (const float*)&Colors::Magenta }
    };

    D3D11_BUFFER_DESC vbd;
    vbd.Usage = D3D11_USAGE_IMMUTABLE;
    vbd.ByteWidth = sizeof(Vertex) * 8;
    vbd.BindFlags = D3D11_BIND_VERTEX_BUFFER;
    vbd.CPUAccessFlags = 0;
    vbd.MiscFlags = 0;
    vbd.StructureByteStride = 0;
    D3D11_SUBRESOURCE_DATA vinitData;
    vinitData.pSysMem = vertices;
    HR(md3dDevice->CreateBuffer(&vbd, &vinitData, &mBoxVB));


    // 创建索引缓冲

    UINT indices[] = {
        // 前表面
        0, 1, 2,
        0, 2, 3,

        // 后表面
        4, 6, 5,
        4, 7, 6,

        // 左表面
        4, 5, 1,
        4, 1, 0,

        // 右表面
        3, 2, 6,
        3, 6, 7,

        // 上表面
        1, 5, 6,
        1, 6, 2,

        // 下表面
        4, 0, 3,
        4, 3, 7
    };

    D3D11_BUFFER_DESC ibd;
    ibd.Usage = D3D11_USAGE_IMMUTABLE;
    ibd.ByteWidth = sizeof(UINT) * 36;
    ibd.BindFlags = D3D11_BIND_INDEX_BUFFER;
    ibd.CPUAccessFlags = 0;
    ibd.MiscFlags = 0;
    ibd.StructureByteStride = 0;
    D3D11_SUBRESOURCE_DATA iinitData;
    iinitData.pSysMem = indices;
    HR(md3dDevice->CreateBuffer(&ibd, &iinitData, &mBoxIB));
}

void BoxApp::BuildFX()
{
    DWORD shaderFlags = 0;
    #if defined( DEBUG ) || defined( _DEBUG )
        shaderFlags |= D3D10_SHADER_DEBUG;
        shaderFlags |= D3D10_SHADER_SKIP_OPTIMIZATION;
    #endif

    ID3D10Blob* compiledShader = 0;
    ID3D10Blob* compilationMsgs = 0;
    HRESULT hr = D3DX11CompileFromFile(L"FX/color.fx", 0, 0, 0, "fx_5_0", shaderFlags,
        0, 0, &compiledShader, &compilationMsgs, 0);

    // compilationMsgs中包含错误或警告信息
    if( compilationMsgs != 0 )
    {
        MessageBoxA(0, (char*)compilationMsgs->GetBufferPointer(), 0, 0);
        ReleaseCOM(compilationMsgs);
    }

    // 就算没有compilationMsgs，也需要确保没有其他错误
    if(FAILED(hr))
    {
        DXTrace(__FILE__, (DWORD)__LINE__, hr, L"D3DX11CompileFromFile", true);
    }

    HR(D3DX11CreateEffectFromMemory(compiledShader->GetBufferPointer(), compiledShader->GetBufferSize(),
        0, md3dDevice, &mFX));

    // 编译完成释放资源
    ReleaseCOM(compiledShader);

    mTech    = mFX->GetTechniqueByName("ColorTech");
    mfxWorldViewProj = mFX->GetVariableByName("gWorldViewProj")->AsMatrix();
}

void BoxApp::BuildVertexLayout()
{
    // 顶点输入布局描述
    D3D11_INPUT_ELEMENT_DESC vertexDesc[] =
    {
        {"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}
    };

    // 创建顶点输入布局
    D3DX11_PASS_DESC passDesc;
    mTech->GetPassByIndex(0)->GetDesc(&passDesc);
    HR(md3dDevice->CreateInputLayout(vertexDesc, 2, passDesc.pIAInputSignature,
        passDesc.IAInputSignatureSize, &mInputLayout));
}