DirectX10 龙书笔记- 一个颜色立方体程序

这篇是作为学习笔记之用，详细代码在Introduction to 3D Game Programming with Directx10里面的扉页，有个网址 www.d3dcoder.net 里面可以下载

这个程序的效果是:

这个demo展示了基本的directx基本的渲染流程.

首先是渲染管线: 它的作用是根据虚拟摄像机视角生成2D图像的基本步骤.

主要是类为ColoredCubeApp

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

	void initApp();  //初始化
	void onResize(); //窗口大小变化时候调用
	void updateScene(float dt); //每一帧调用,负责更新参数
	void drawScene(); //每一帧调用,负责绘制

private:
	void buildFX(); //着色器
	void buildVertexLayouts(); //输入汇编器，构建图元
 
private:
	
	Box mBox;

	ID3D10Effect* mFX;
	ID3D10EffectTechnique* mTech;
	ID3D10InputLayout* mVertexLayout;
	ID3D10EffectMatrixVariable* mfxWVPVar;

	D3DXMATRIX mView;
	D3DXMATRIX mProj;
	D3DXMATRIX mWVP;

	float mTheta;
	float mPhi;
};

这个类中的initAPP()为初始化渲染做准备

void ColoredCubeApp::initApp()
{
	D3DApp::initApp();
	mBox.init(md3dDevice, 0.3f);  //这个是所要创建立方体的初始化。 提供了顶点缓冲区，和索引缓冲区
	buildFX(); //这个是顶点着色器、几何着色器、像素着色器的配置
	buildVertexLayouts();//根据以上信息构建图元
}

下面看具体mBox.init是怎么初始化立方体的
void Box::init(ID3D10Device* device, float scale)
{
	md3dDevice = device;
 
	mNumVertices = 8;
	mNumFaces    = 12; // 2 per quad

	// Create vertex buffer
    Vertex vertices[] =
    {
		{D3DXVECTOR3(-1.0f, -1.0f, -1.0f), WHITE},
		{D3DXVECTOR3(-1.0f, +1.0f, -1.0f), BLACK},
		{D3DXVECTOR3(+1.0f, +1.0f, -1.0f), RED},
		{D3DXVECTOR3(+1.0f, -1.0f, -1.0f), GREEN},
		{D3DXVECTOR3(-1.0f, -1.0f, +1.0f), BLUE},
		{D3DXVECTOR3(-1.0f, +1.0f, +1.0f), YELLOW},
		{D3DXVECTOR3(+1.0f, +1.0f, +1.0f), CYAN},
		{D3DXVECTOR3(+1.0f, -1.0f, +1.0f), MAGENTA},
    };

	// Scale the box.
	for(DWORD i = 0; i < mNumVertices; ++i)
		vertices[i].pos *= scale;

	//顶点缓冲区
    D3D10_BUFFER_DESC vbd;
    vbd.Usage = D3D10_USAGE_IMMUTABLE;
    vbd.ByteWidth = sizeof(Vertex) * mNumVertices;
    vbd.BindFlags = D3D10_BIND_VERTEX_BUFFER;
    vbd.CPUAccessFlags = 0;
    vbd.MiscFlags = 0;
    D3D10_SUBRESOURCE_DATA vinitData;
    vinitData.pSysMem = vertices;
    HR(md3dDevice->CreateBuffer(&vbd, &vinitData, &mVB));


	// Create the index buffer 
    //索引缓冲区
	DWORD indices[] = {
		// front face
		0, 1, 2,
		0, 2, 3,

		// back face
		4, 6, 5,
		4, 7, 6,

		// left face
		4, 5, 1,
		4, 1, 0,

		// right face
		3, 2, 6,
		3, 6, 7,

		// top face
		1, 5, 6,
		1, 6, 2,

		// bottom face
		4, 0, 3, 
		4, 3, 7
	};

	D3D10_BUFFER_DESC ibd;
    ibd.Usage = D3D10_USAGE_IMMUTABLE;
    ibd.ByteWidth = sizeof(DWORD) * mNumFaces*3;
    ibd.BindFlags = D3D10_BIND_INDEX_BUFFER;
    ibd.CPUAccessFlags = 0;
    ibd.MiscFlags = 0;
    D3D10_SUBRESOURCE_DATA iinitData;
    iinitData.pSysMem = indices;
    HR(md3dDevice->CreateBuffer(&ibd, &iinitData, &mIB));
}

从以上可知，主要作用就是先构建所需要的不重复的点，然后构建一个立方体索引点(索引是为了节约资源，不必再重复构建点)。

下面看buildFX() 里面的内容

hr = D3DX10CreateEffectFromFile(L"color.fx", 0, 0,

"fx_4_0",shaderFlags, 0, md3dDevice,0, 0, &mFX, &compilationErrors,0);

主要为这一句。

其中color.fx 是一个文本文件

//=============================================================================
// color.fx by Frank Luna (C) 2008 All Rights Reserved.
//
// Transforms and colors geometry.
//=============================================================================

cbuffer cbPerObject
{
	float4x4 gWVP; 
};

void VS(float3 iPosL  : POSITION,
        float4 iColor : COLOR,
        out float4 oPosH  : SV_POSITION,
        out float4 oColor : COLOR)
{
	// Transform to homogeneous clip space.
	oPosH = mul(float4(iPosL, 1.0f), gWVP);
	
	// Just pass vertex color into the pixel shader.
    oColor = iColor;
}

float4 PS(float4 posH  : SV_POSITION,
          float4 color : COLOR) : SV_Target
{
    return color;
}

technique10 ColorTech
{
    pass P0
    {
        SetVertexShader( CompileShader( vs_4_0, VS() ) );
        SetGeometryShader( NULL );
        SetPixelShader( CompileShader( ps_4_0, PS() ) );
    }
}

以上可以看成类c++的文件，就是定义一组操作。
然后通过
void ColoredCubeApp::buildVertexLayouts()
{
	// Create the vertex input layout.
	D3D10_INPUT_ELEMENT_DESC vertexDesc[] =
	{
		{"POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D10_INPUT_PER_VERTEX_DATA, 0},
		{"COLOR",    0, DXGI_FORMAT_R32G32B32A32_FLOAT, 0, 12, D3D10_INPUT_PER_VERTEX_DATA, 0}
	};

	// Create the input layout
    D3D10_PASS_DESC PassDesc;
    mTech->GetPassByIndex(0)->GetDesc(&PassDesc);
    HR(md3dDevice->CreateInputLayout(vertexDesc, 2, PassDesc.pIAInputSignature,
		PassDesc.IAInputSignatureSize, &mVertexLayout));
}

上面这个函数调用color.fx里面相应的操作函数实现图元的构建。

准备工作完成了。现在就是绘制过程了

void ColoredCubeApp::drawScene()
{
	D3DApp::drawScene();

	// Restore default states, input layout and primitive topology 
	// because mFont->DrawText changes them.  Note that we can 
	// restore the default states by passing null.
	//md3dDevice->OMSetDepthStencilState(0, 0);
	float blendFactors[] = {0.0f, 0.0f, 0.0f, 0.0f};
	//md3dDevice->OMSetBlendState(0, blendFactors, 0xffffffff);
    md3dDevice->IASetInputLayout(mVertexLayout);
	//图ª?元a列¢D表À¨ª-三¨y角?形?
    md3dDevice->IASetPrimitiveTopology(D3D10_PRIMITIVE_TOPOLOGY_LINESTRIP);

   
	// set constants
	mWVP = mView*mProj;
	mfxWVPVar->SetMatrix((float*)&mWVP);

    D3D10_TECHNIQUE_DESC techDesc;
    mTech->GetDesc( &techDesc );
    for(UINT p = 0; p < techDesc.Passes; ++p)
    {
        mTech->GetPassByIndex( p )->Apply(0);//更¨¹新?GPU 常¡ê量¢?缓o冲?区?，ê?将?着Á?色¦?器¡Â绑㨮定¡§到Ì?管¨¹线?，ê?启?动¡¥pass
        
		mBox.draw();
    }

	
	mSwapChain->Present(0, 0);
}

void ColoredCubeApp::updateScene(float dt)
{
	D3DApp::updateScene(dt);

	// Update angles based on input to orbit camera around box.
	if(GetAsyncKeyState('A') & 0x8000)	mTheta -= 2.0f*dt;
	if(GetAsyncKeyState('D') & 0x8000)	mTheta += 2.0f*dt;
	if(GetAsyncKeyState('W') & 0x8000)	mPhi -= 2.0f*dt;
	if(GetAsyncKeyState('S') & 0x8000)	mPhi += 2.0f*dt;

	// Restrict the angle mPhi.
	if( mPhi < 0.1f )	mPhi = 0.1f;
	if( mPhi > PI-0.1f)	mPhi = PI-0.1f;

	// Convert Spherical to Cartesian coordinates: mPhi measured from +y
	// and mTheta measured counterclockwise from -z.
	float x =  5.0f*sinf(mPhi)*sinf(mTheta);
	float z = -5.0f*sinf(mPhi)*cosf(mTheta);
	float y =  5.0f*cosf(mPhi);

	// Build the view matrix.   观?察¨¬者?到Ì?世º¨¤界?的Ì?矩?阵¨®
	D3DXVECTOR3 pos(x, y, z);
	D3DXVECTOR3 target(0.0f, 0.0f, 0.0f);
	D3DXVECTOR3 up(0.0f, 1.0f, 0.0f);
	D3DXMatrixLookAtLH(&mView, &pos, &target, &up);
}

目前还只是第一个比较完整的demo 细节代码很多还没有理解透彻。我们能了解个大概流程就可以啦。后面会越学越懂的