DirectX/10.0/Direct3D/2D 渲染

能够将 2D 图像渲染到屏幕上非常有用。例如，大多数用户界面、精灵系统和文本引擎都是由 2D 图像组成的。DirectX 11 允许您通过将 2D 图像映射到多边形，然后使用正交投影矩阵进行渲染来渲染 2D 图像。

2D 屏幕坐标

要将 2D 图像渲染到屏幕上，您需要计算屏幕 X 和 Y 坐标。对于 DirectX，屏幕的中心是 0,0。从那里，屏幕的左侧和底部朝负方向移动。屏幕的右侧和顶部朝正方向移动。例如，以 1024x768 分辨率的屏幕为例，屏幕边界的坐标如下所示

因此请记住，您所有 2D 渲染都需要使用这些屏幕坐标计算，并且您还需要用户窗口/屏幕的大小才能正确放置 2D 图像。

在 DirectX 11 中禁用 Z 缓冲区

要进行 2D 绘制，您应该禁用 Z 缓冲区。当 Z 缓冲区关闭时，它将在该像素位置的任何内容之上写入 2D 数据。确保使用画家算法，并从后到前绘制，以确保您获得预期的渲染输出。完成绘制 2D 图形后，请再次启用 Z 缓冲区，以便您可以正确地再次渲染 3D 对象。

要打开和关闭 Z 缓冲区，您需要创建一个第二个深度模板状态，与您的 3D 状态相同，只是将 DepthEnable 设置为 false。然后，只需使用 OMSetDepthStencilState 在这两种状态之间切换即可打开和关闭 Z 缓冲区。

动态顶点缓冲区

另一个将要介绍的新概念是动态顶点缓冲区。到目前为止，我们在之前的教程中使用了静态顶点缓冲区。静态顶点缓冲区的问题是，您永远无法更改缓冲区中的数据。另一方面，动态顶点缓冲区允许我们在需要时在每一帧内操作顶点缓冲区内部的信息。这些缓冲区比静态顶点缓冲区慢得多，但这是为了额外功能而付出的代价。

我们使用 2D 渲染的动态顶点缓冲区的原因是我们经常希望将 2D 图像移动到屏幕上的不同位置。一个很好的例子是鼠标指针，它经常被移动，因此表示它在屏幕上的位置的顶点数据也需要经常更改。

两点需要注意。除非绝对需要，否则不要使用动态顶点缓冲区，它们比静态缓冲区慢得多。其次，不要在每一帧都销毁和重新创建静态顶点缓冲区，这会导致显卡完全锁定（我在 ATI 上见过，但没有在 Nvidia 上见过），并且与使用动态顶点缓冲区相比，整体性能要差得多。

DirectX 11 中的正交投影

在 2D 中进行渲染所需的最后一个新概念是在正规的 3D 投影矩阵的基础上使用正交投影矩阵。这将允许您渲染到 2D 屏幕坐标。请记住，我们已经在 Direct3D 初始化代码中创建了此矩阵

	// Create an orthographic projection matrix for 2D rendering.
	D3DXMatrixOrthoLH(&m_orthoMatrix, (float)screenWidth, (float)screenHeight, screenNear, screenDepth);

框架

本教程中的代码基于之前的教程。本教程的主要区别在于 ModelClass 已被 BitmapClass 替换，我们再次使用 TextureShaderClass 而不是 LightShaderClass。框架将如下所示

Bitmapclass.h

BitmapClass 将用于表示需要渲染到屏幕上的单个 2D 图像。对于您拥有的每个 2D 图像，您都需要一个新的 BitmapClass。请注意，此类只是重新编写的 ModelClass，用于处理 2D 图像而不是 3D 对象。

////////////////////////////////////////////////////////////////////////////////
// Filename: bitmapclass.h
////////////////////////////////////////////////////////////////////////////////
#ifndef _BITMAPCLASS_H_
#define _BITMAPCLASS_H_

//////////////
// INCLUDES //
//////////////
#include <d3d11.h>
#include <d3dx10math.h>

///////////////////////
// MY CLASS INCLUDES //
///////////////////////
#include "textureclass.h"

////////////////////////////////////////////////////////////////////////////////
// Class name: BitmapClass
////////////////////////////////////////////////////////////////////////////////
class BitmapClass
{
private:

每个位图图像仍然是渲染类似于 3D 对象的多边形对象。对于 2D 图像，我们只需要一个位置向量和纹理坐标。

	struct VertexType
	{
		D3DXVECTOR3 position;
		D3DXVECTOR2 texture;
	};

public:
	BitmapClass();
	BitmapClass(const BitmapClass&);
	~BitmapClass();

	bool Initialize(ID3D11Device*, int, int, WCHAR*, int, int);
	void Shutdown();
	bool Render(ID3D11DeviceContext*, int, int);

	int GetIndexCount();
	ID3D11ShaderResourceView* GetTexture();

private:
	bool InitializeBuffers(ID3D11Device*);
	void ShutdownBuffers();
	bool UpdateBuffers(ID3D11DeviceContext*, int, int);
	void RenderBuffers(ID3D11DeviceContext*);

	bool LoadTexture(ID3D11Device*, WCHAR*);
	void ReleaseTexture();

private:
	ID3D11Buffer *m_vertexBuffer, *m_indexBuffer;
	int m_vertexCount, m_indexCount;
	TextureClass* m_Texture;

BitmapClass 需要维护 3D 模型不会维护的一些额外信息，例如屏幕大小、位图大小以及最后一次渲染的位置。我们在这里添加了额外的私有变量来跟踪这些额外信息。

	int m_screenWidth, m_screenHeight;
	int m_bitmapWidth, m_bitmapHeight;
	int m_previousPosX, m_previousPosY;
};

#endif

Bitmapclass.cpp

////////////////////////////////////////////////////////////////////////////////
// Filename: bitmapclass.cpp
////////////////////////////////////////////////////////////////////////////////
#include "bitmapclass.h"

类构造函数初始化类中的所有私有指针。

BitmapClass::BitmapClass()
{
	m_vertexBuffer = 0;
	m_indexBuffer = 0;
	m_Texture = 0;
}

BitmapClass::BitmapClass(const BitmapClass& other)
{
}

BitmapClass::~BitmapClass()
{
}

bool BitmapClass::Initialize(ID3D11Device* device, int screenWidth, int screenHeight, WCHAR* textureFilename, int bitmapWidth, int bitmapHeight)
{
	bool result;

在 Initialize 函数中，屏幕大小和图像大小都被存储。这些对于在渲染期间生成精确的顶点位置是必需的。请注意，图像的像素不需要与使用的纹理完全相同，您可以将其设置为任何大小，并使用您想要的任何大小的纹理。

	// Store the screen size.
	m_screenWidth = screenWidth;
	m_screenHeight = screenHeight;

	// Store the size in pixels that this bitmap should be rendered at.
	m_bitmapWidth = bitmapWidth;
	m_bitmapHeight = bitmapHeight;

之前的渲染位置首先初始化为负一。这将是一个重要的变量，它将定位最后绘制此图像的位置。如果自上一帧以来图像位置没有改变，那么它不会修改动态顶点缓冲区，这将为我们节省一些周期。

	// Initialize the previous rendering position to negative one.
	m_previousPosX = -1;
	m_previousPosY = -1;

然后创建缓冲区，并加载此位图图像的纹理。

	// Initialize the vertex and index buffers.
	result = InitializeBuffers(device);
	if(!result)
	{
		return false;
	}

	// Load the texture for this model.
	result = LoadTexture(device, textureFilename);
	if(!result)
	{
		return false;
	}

	return true;
}

Shutdown 函数将释放顶点和索引缓冲区以及用于位图图像的纹理。

void BitmapClass::Shutdown()
{
	// Release the model texture.
	ReleaseTexture();

	// Shutdown the vertex and index buffers.
	ShutdownBuffers();

	return;
}

Render 将 2D 图像的缓冲区放到显卡上。作为输入，它获取在屏幕上渲染图像的位置。UpdateBuffers 函数使用位置参数调用。如果自上一帧以来位置已更改，则它将更新动态顶点缓冲区中顶点的位置到新位置。如果没有，它将跳过 UpdateBuffers 函数。之后，RenderBuffers 函数将为渲染准备最终的顶点/索引。

bool BitmapClass::Render(ID3D11DeviceContext* deviceContext, int positionX, int positionY)
{
	bool result;

	// Re-build the dynamic vertex buffer for rendering to possibly a different location on the screen.
	result = UpdateBuffers(deviceContext, positionX, positionY);
	if(!result)
	{
		return false;
	}

	// Put the vertex and index buffers on the graphics pipeline to prepare them for drawing.
	RenderBuffers(deviceContext);

	return true;
}

GetIndexCount 返回 2D 图像的索引数量。这几乎总是六个。

int BitmapClass::GetIndexCount()
{
	return m_indexCount;
}

GetTexture 函数返回指向此 2D 图像的纹理资源的指针。着色器将调用此函数，以便它在绘制缓冲区时可以访问图像。

ID3D11ShaderResourceView* BitmapClass::GetTexture()
{
	return m_Texture->GetTexture();
}

InitializeBuffers 是用于构建顶点和索引缓冲区的函数，这些缓冲区将用于绘制 2D 图像。

bool BitmapClass::InitializeBuffers(ID3D11Device* device)
{
	VertexType* vertices;
	unsigned long* indices;
	D3D11_BUFFER_DESC vertexBufferDesc, indexBufferDesc;
	D3D11_SUBRESOURCE_DATA vertexData, indexData;
	HRESULT result;
	int i;

我们将顶点设置为六个，因为我们正在用两个三角形创建一个正方形，所以需要六个点。索引将相同。

	// Set the number of vertices in the vertex array.
	m_vertexCount = 6;

	// Set the number of indices in the index array.
	m_indexCount = m_vertexCount;

	// Create the vertex array.
	vertices = new VertexType[m_vertexCount];
	if(!vertices)
	{
		return false;
	}

	// Create the index array.
	indices = new unsigned long[m_indexCount];
	if(!indices)
	{
		return false;
	}

	// Initialize vertex array to zeros at first.
	memset(vertices, 0, (sizeof(VertexType) * m_vertexCount));

	// Load the index array with data.
	for(i=0; i<m_indexCount; i++)
	{
		indices[i] = i;
	}

以下是与 ModelClass 相比的重大变化。我们现在正在创建一个动态顶点缓冲区，以便我们可以在需要时在每一帧内修改顶点缓冲区内部的数据。为了使其动态，我们在描述中将 Usage 设置为 D3D11_USAGE_DYNAMIC，并将 CPUAccessFlags 设置为 D3D11_CPU_ACCESS_WRITE。

	// Set up the description of the static vertex buffer.
	vertexBufferDesc.Usage = D3D11_USAGE_DYNAMIC;
	vertexBufferDesc.ByteWidth = sizeof(VertexType) * m_vertexCount;
	vertexBufferDesc.BindFlags = D3D11_BIND_VERTEX_BUFFER;
	vertexBufferDesc.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;
	vertexBufferDesc.MiscFlags = 0;
	vertexBufferDesc.StructureByteStride = 0;

	// Give the subresource structure a pointer to the vertex data.
	vertexData.pSysMem = vertices;
	vertexData.SysMemPitch = 0;
	vertexData.SysMemSlicePitch = 0;

	// Now create the vertex buffer.
	result = device->CreateBuffer(&vertexBufferDesc, &vertexData, &m_vertexBuffer);
	if(FAILED(result))
	{
		return false;
	}

我们不需要使索引缓冲区动态，因为即使顶点的坐标可能发生变化，六个索引也始终指向相同的六个顶点。

	// Set up the description of the static index buffer.
	indexBufferDesc.Usage = D3D11_USAGE_DEFAULT;
	indexBufferDesc.ByteWidth = sizeof(unsigned long) * m_indexCount;
	indexBufferDesc.BindFlags = D3D11_BIND_INDEX_BUFFER;
	indexBufferDesc.CPUAccessFlags = 0;
	indexBufferDesc.MiscFlags = 0;
	indexBufferDesc.StructureByteStride = 0;

	// Give the subresource structure a pointer to the index data.
	indexData.pSysMem = indices;
	indexData.SysMemPitch = 0;
	indexData.SysMemSlicePitch = 0;

	// Create the index buffer.
	result = device->CreateBuffer(&indexBufferDesc, &indexData, &m_indexBuffer);
	if(FAILED(result))
	{
		return false;
	}

	// Release the arrays now that the vertex and index buffers have been created and loaded.
	delete [] vertices;
	vertices = 0;

	delete [] indices;
	indices = 0;

	return true;
}

ShutdownBuffers 释放顶点和索引缓冲区。

void BitmapClass::ShutdownBuffers()
{
	// Release the index buffer.
	if(m_indexBuffer)
	{
		m_indexBuffer->Release();
		m_indexBuffer = 0;
	}

	// Release the vertex buffer.
	if(m_vertexBuffer)
	{
		m_vertexBuffer->Release();
		m_vertexBuffer = 0;
	}

	return;
}

UpdateBuffers 函数在每一帧中调用，以更新动态顶点缓冲区的内容，以便根据需要重新定位屏幕上的 2D 位图图像。

bool BitmapClass::UpdateBuffers(ID3D11DeviceContext* deviceContext, int positionX, int positionY)
{
	float left, right, top, bottom;
	VertexType* vertices;
	D3D11_MAPPED_SUBRESOURCE mappedResource;
	VertexType* verticesPtr;
	HRESULT result;

我们检查渲染此图像的位置是否已更改。如果它没有改变，那么我们只需退出，因为顶点缓冲区不需要为这一帧进行任何更改。此检查可以为我们节省很多处理时间。

	// If the position we are rendering this bitmap to has not changed then don't update the vertex buffer since it
	// currently has the correct parameters.
	if((positionX == m_previousPosX) && (positionY == m_previousPosY))
	{
		return true;
	}

如果渲染此图像的位置已更改，则我们记录新位置，以便下次调用此函数时可以使用。

	// If it has changed then update the position it is being rendered to.
	m_previousPosX = positionX;
	m_previousPosY = positionY;

需要计算图像的四条边。请参阅教程顶部的图表以了解完整说明。

	// Calculate the screen coordinates of the left side of the bitmap.
	left = (float)((m_screenWidth / 2) * -1) + (float)positionX;

	// Calculate the screen coordinates of the right side of the bitmap.
	right = left + (float)m_bitmapWidth;

	// Calculate the screen coordinates of the top of the bitmap.
	top = (float)(m_screenHeight / 2) - (float)positionY;

	// Calculate the screen coordinates of the bottom of the bitmap.
	bottom = top - (float)m_bitmapHeight;

现在坐标已计算完毕，创建一个临时顶点数组，并用新的六个顶点填充它。

	// Create the vertex array.
	vertices = new VertexType[m_vertexCount];
	if(!vertices)
	{
		return false;
	}

	// Load the vertex array with data.
	// First triangle.
	vertices[0].position = D3DXVECTOR3(left, top, 0.0f);  // Top left.
	vertices[0].texture = D3DXVECTOR2(0.0f, 0.0f);

	vertices[1].position = D3DXVECTOR3(right, bottom, 0.0f);  // Bottom right.
	vertices[1].texture = D3DXVECTOR2(1.0f, 1.0f);

	vertices[2].position = D3DXVECTOR3(left, bottom, 0.0f);  // Bottom left.
	vertices[2].texture = D3DXVECTOR2(0.0f, 1.0f);

	// Second triangle.
	vertices[3].position = D3DXVECTOR3(left, top, 0.0f);  // Top left.
	vertices[3].texture = D3DXVECTOR2(0.0f, 0.0f);

	vertices[4].position = D3DXVECTOR3(right, top, 0.0f);  // Top right.
	vertices[4].texture = D3DXVECTOR2(1.0f, 0.0f);

	vertices[5].position = D3DXVECTOR3(right, bottom, 0.0f);  // Bottom right.
	vertices[5].texture = D3DXVECTOR2(1.0f, 1.0f);

现在使用 Map 和 memcpy 函数将顶点数组的内容复制到顶点缓冲区中。

	// Lock the vertex buffer so it can be written to.
	result = deviceContext->Map(m_vertexBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &mappedResource);
	if(FAILED(result))
	{
		return false;
	}

	// Get a pointer to the data in the vertex buffer.
	verticesPtr = (VertexType*)mappedResource.pData;

	// Copy the data into the vertex buffer.
	memcpy(verticesPtr, (void*)vertices, (sizeof(VertexType) * m_vertexCount));

	// Unlock the vertex buffer.
	deviceContext->Unmap(m_vertexBuffer, 0);

	// Release the vertex array as it is no longer needed.
	delete [] vertices;
	vertices = 0;

	return true;
}

RenderBuffers 函数设置 GPU 上的顶点和索引缓冲区，以便着色器进行绘制。

void BitmapClass::RenderBuffers(ID3D11DeviceContext* deviceContext)
{
	unsigned int stride;
	unsigned int offset;

	// Set vertex buffer stride and offset.
	stride = sizeof(VertexType); 
	offset = 0;
    
	// Set the vertex buffer to active in the input assembler so it can be rendered.
	deviceContext->IASetVertexBuffers(0, 1, &m_vertexBuffer, &stride, &offset);

	// Set the index buffer to active in the input assembler so it can be rendered.
	deviceContext->IASetIndexBuffer(m_indexBuffer, DXGI_FORMAT_R32_UINT, 0);

	// Set the type of primitive that should be rendered from this vertex buffer, in this case triangles.
	deviceContext->IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST);

	return;
}

以下函数加载用于绘制 2D 图像的纹理。

bool BitmapClass::LoadTexture(ID3D11Device* device, WCHAR* filename)
{
	bool result;

	// Create the texture object.
	m_Texture = new TextureClass;
	if(!m_Texture)
	{
		return false;
	}

	// Initialize the texture object.
	result = m_Texture->Initialize(device, filename);
	if(!result)
	{
		return false;
	}

	return true;
}

此 ReleaseTexture 函数释放已加载的纹理。

void BitmapClass::ReleaseTexture()
{
	// Release the texture object.
	if(m_Texture)
	{
		m_Texture->Shutdown();
		delete m_Texture;
		m_Texture = 0;
	}

	return;
}

D3dclass.h

D3DClass 已修改为处理启用和禁用 Z 缓冲区。

////////////////////////////////////////////////////////////////////////////////
// Filename: d3dclass.h
////////////////////////////////////////////////////////////////////////////////
#ifndef _D3DCLASS_H_
#define _D3DCLASS_H_

/////////////
// LINKING //
/////////////
#pragma comment(lib, "dxgi.lib")
#pragma comment(lib, "d3d11.lib")
#pragma comment(lib, "d3dx11.lib")
#pragma comment(lib, "d3dx10.lib")

//////////////
// INCLUDES //
//////////////
#include <dxgi.h>
#include <d3dcommon.h>
#include <d3d11.h>
#include <d3dx10math.h>

////////////////////////////////////////////////////////////////////////////////
// Class name: D3DClass
////////////////////////////////////////////////////////////////////////////////
class D3DClass
{
public:
	D3DClass();
	D3DClass(const D3DClass&);
	~D3DClass();

	bool Initialize(int, int, bool, HWND, bool, float, float);
	void Shutdown();
	
	void BeginScene(float, float, float, float);
	void EndScene();

	ID3D11Device* GetDevice();
	ID3D11DeviceContext* GetDeviceContext();

	void GetProjectionMatrix(D3DXMATRIX&);
	void GetWorldMatrix(D3DXMATRIX&);
	void GetOrthoMatrix(D3DXMATRIX&);

	void GetVideoCardInfo(char*, int&);

我们现在在 D3DClass 中新增了两个函数，用于在渲染 2D 图像时打开和关闭 Z 缓冲区。

	void TurnZBufferOn();
	void TurnZBufferOff();

private:
	bool m_vsync_enabled;
	int m_videoCardMemory;
	char m_videoCardDescription[128];
	IDXGISwapChain* m_swapChain;
	ID3D11Device* m_device;
	ID3D11DeviceContext* m_deviceContext;
	ID3D11RenderTargetView* m_renderTargetView;
	ID3D11Texture2D* m_depthStencilBuffer;
	ID3D11DepthStencilState* m_depthStencilState;
	ID3D11DepthStencilView* m_depthStencilView;
	ID3D11RasterizerState* m_rasterState;
	D3DXMATRIX m_projectionMatrix;
	D3DXMATRIX m_worldMatrix;
	D3DXMATRIX m_orthoMatrix;

还有一种用于 2D 绘制的深度模板状态。

	ID3D11DepthStencilState* m_depthDisabledStencilState;

};

#endif

D3dclass.cpp

我们将只介绍自纹理教程以来在此类中更改的功能。

////////////////////////////////////////////////////////////////////////////////
// Filename: d3dclass.cpp
////////////////////////////////////////////////////////////////////////////////
#include "d3dclass.h"

D3DClass::D3DClass()
{
	m_swapChain = 0;
	m_device = 0;
	m_deviceContext = 0;
	m_renderTargetView = 0;
	m_depthStencilBuffer = 0;
	m_depthStencilState = 0;
	m_depthStencilView = 0;
	m_rasterState = 0;

在类构造函数中将新的深度模板状态初始化为 null。

	m_depthDisabledStencilState = 0;

}

D3DClass::D3DClass(const D3DClass& other)
{
}

D3DClass::~D3DClass()
{
}

bool D3DClass::Initialize(int screenWidth, int screenHeight, bool vsync, HWND hwnd, bool fullscreen, float screenDepth, float screenNear)
{
	HRESULT result;
	IDXGIFactory* factory;
	IDXGIAdapter* adapter;
	IDXGIOutput* adapterOutput;
	unsigned int numModes, i, numerator, denominator, stringLength;
	DXGI_MODE_DESC* displayModeList;
	DXGI_ADAPTER_DESC adapterDesc;
	int error;
	DXGI_SWAP_CHAIN_DESC swapChainDesc;
	D3D_FEATURE_LEVEL featureLevel;
	ID3D11Texture2D* backBufferPtr;
	D3D11_TEXTURE2D_DESC depthBufferDesc;
	D3D11_DEPTH_STENCIL_DESC depthStencilDesc;
	D3D11_DEPTH_STENCIL_VIEW_DESC depthStencilViewDesc;
	D3D11_RASTERIZER_DESC rasterDesc;
	D3D11_VIEWPORT viewport;
	float fieldOfView, screenAspect;

我们有一个新的深度模板描述变量用于设置新的深度模板。

	D3D11_DEPTH_STENCIL_DESC depthDisabledStencilDesc;

	// Store the vsync setting.
	m_vsync_enabled = vsync;

	// Create a DirectX graphics interface factory.
	result = CreateDXGIFactory(__uuidof(IDXGIFactory), (void**)&factory);
	if(FAILED(result))
	{
		return false;
	}

	// Use the factory to create an adapter for the primary graphics interface (video card).
	result = factory->EnumAdapters(0, &adapter);
	if(FAILED(result))
	{
		return false;
	}

	// Enumerate the primary adapter output (monitor).
	result = adapter->EnumOutputs(0, &adapterOutput);
	if(FAILED(result))
	{
		return false;
	}

	// Get the number of modes that fit the DXGI_FORMAT_R8G8B8A8_UNORM display format for the adapter output (monitor).
	result = adapterOutput->GetDisplayModeList(DXGI_FORMAT_R8G8B8A8_UNORM, DXGI_ENUM_MODES_INTERLACED, &numModes, NULL);
	if(FAILED(result))
	{
		return false;
	}

	// Create a list to hold all the possible display modes for this monitor/video card combination.
	displayModeList = new DXGI_MODE_DESC[numModes];
	if(!displayModeList)
	{
		return false;
	}

	// Now fill the display mode list structures.
	result = adapterOutput->GetDisplayModeList(DXGI_FORMAT_R8G8B8A8_UNORM, DXGI_ENUM_MODES_INTERLACED, &numModes, displayModeList);
	if(FAILED(result))
	{
		return false;
	}

	// Now go through all the display modes and find the one that matches the screen width and height.
	// When a match is found store the numerator and denominator of the refresh rate for that monitor.
	for(i=0; i<numModes; i++)
	{
		if(displayModeList[i].Width == (unsigned int)screenWidth)
		{
			if(displayModeList[i].Height == (unsigned int)screenHeight)
			{
				numerator = displayModeList[i].RefreshRate.Numerator;
				denominator = displayModeList[i].RefreshRate.Denominator;
			}
		}
	}

	// Get the adapter (video card) description.
	result = adapter->GetDesc(&adapterDesc);
	if(FAILED(result))
	{
		return false;
	}

	// Store the dedicated video card memory in megabytes.
	m_videoCardMemory = (int)(adapterDesc.DedicatedVideoMemory / 1024 / 1024);

	// Convert the name of the video card to a character array and store it.
	error = wcstombs_s(&stringLength, m_videoCardDescription, 128, adapterDesc.Description, 128);
	if(error != 0)
	{
		return false;
	}

	// Release the display mode list.
	delete [] displayModeList;
	displayModeList = 0;

	// Release the adapter output.
	adapterOutput->Release();
	adapterOutput = 0;

	// Release the adapter.
	adapter->Release();
	adapter = 0;

	// Release the factory.
	factory->Release();
	factory = 0;

	// Initialize the swap chain description.
	ZeroMemory(&swapChainDesc, sizeof(swapChainDesc));

	// Set to a single back buffer.
	swapChainDesc.BufferCount = 1;

	// Set the width and height of the back buffer.
	swapChainDesc.BufferDesc.Width = screenWidth;
	swapChainDesc.BufferDesc.Height = screenHeight;

	// Set regular 32-bit surface for the back buffer.
	swapChainDesc.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;

	// Set the refresh rate of the back buffer.
	if(m_vsync_enabled)
	{
		swapChainDesc.BufferDesc.RefreshRate.Numerator = numerator;
		swapChainDesc.BufferDesc.RefreshRate.Denominator = denominator;
	}
	else
	{
		swapChainDesc.BufferDesc.RefreshRate.Numerator = 0;
		swapChainDesc.BufferDesc.RefreshRate.Denominator = 1;
	}

	// Set the usage of the back buffer.
	swapChainDesc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;

	// Set the handle for the window to render to.
	swapChainDesc.OutputWindow = hwnd;

	// Turn multisampling off.
	swapChainDesc.SampleDesc.Count = 1;
	swapChainDesc.SampleDesc.Quality = 0;

	// Set to full screen or windowed mode.
	if(fullscreen)
	{
		swapChainDesc.Windowed = false;
	}
	else
	{
		swapChainDesc.Windowed = true;
	}

	// Set the scan line ordering and scaling to unspecified.
	swapChainDesc.BufferDesc.ScanlineOrdering = DXGI_MODE_SCANLINE_ORDER_UNSPECIFIED;
	swapChainDesc.BufferDesc.Scaling = DXGI_MODE_SCALING_UNSPECIFIED;

	// Discard the back buffer contents after presenting.
	swapChainDesc.SwapEffect = DXGI_SWAP_EFFECT_DISCARD;

	// Don't set the advanced flags.
	swapChainDesc.Flags = 0;

	// Set the feature level to DirectX 11.
	featureLevel = D3D_FEATURE_LEVEL_11_0;

	// Create the swap chain, Direct3D device, and Direct3D device context.
	result = D3D11CreateDeviceAndSwapChain(NULL, D3D_DRIVER_TYPE_HARDWARE, NULL, 0, &featureLevel, 1, D3D11_SDK_VERSION, &swapChainDesc, &m_swapChain, 
					       &m_device, NULL, &m_deviceContext);
	if(FAILED(result))
	{
		return false;
	}

	// Get the pointer to the back buffer.
	result = m_swapChain->GetBuffer(0, __uuidof(ID3D11Texture2D), (LPVOID*)&backBufferPtr);
	if(FAILED(result))
	{
		return false;
	}

	// Create the render target view with the back buffer pointer.
	result = m_device->CreateRenderTargetView(backBufferPtr, NULL, &m_renderTargetView);
	if(FAILED(result))
	{
		return false;
	}

	// Release pointer to the back buffer as we no longer need it.
	backBufferPtr->Release();
	backBufferPtr = 0;

	// Initialize the description of the depth buffer.
	ZeroMemory(&depthBufferDesc, sizeof(depthBufferDesc));

	// Set up the description of the depth buffer.
	depthBufferDesc.Width = screenWidth;
	depthBufferDesc.Height = screenHeight;
	depthBufferDesc.MipLevels = 1;
	depthBufferDesc.ArraySize = 1;
	depthBufferDesc.Format = DXGI_FORMAT_D24_UNORM_S8_UINT;
	depthBufferDesc.SampleDesc.Count = 1;
	depthBufferDesc.SampleDesc.Quality = 0;
	depthBufferDesc.Usage = D3D11_USAGE_DEFAULT;
	depthBufferDesc.BindFlags = D3D11_BIND_DEPTH_STENCIL;
	depthBufferDesc.CPUAccessFlags = 0;
	depthBufferDesc.MiscFlags = 0;

	// Create the texture for the depth buffer using the filled out description.
	result = m_device->CreateTexture2D(&depthBufferDesc, NULL, &m_depthStencilBuffer);
	if(FAILED(result))
	{
		return false;
	}

	// Initialize the description of the stencil state.
	ZeroMemory(&depthStencilDesc, sizeof(depthStencilDesc));

	// Set up the description of the stencil state.
	depthStencilDesc.DepthEnable = true;
	depthStencilDesc.DepthWriteMask = D3D11_DEPTH_WRITE_MASK_ALL;
	depthStencilDesc.DepthFunc = D3D11_COMPARISON_LESS;

	depthStencilDesc.StencilEnable = true;
	depthStencilDesc.StencilReadMask = 0xFF;
	depthStencilDesc.StencilWriteMask = 0xFF;

	// Stencil operations if pixel is front-facing.
	depthStencilDesc.FrontFace.StencilFailOp = D3D11_STENCIL_OP_KEEP;
	depthStencilDesc.FrontFace.StencilDepthFailOp = D3D11_STENCIL_OP_INCR;
	depthStencilDesc.FrontFace.StencilPassOp = D3D11_STENCIL_OP_KEEP;
	depthStencilDesc.FrontFace.StencilFunc = D3D11_COMPARISON_ALWAYS;

	// Stencil operations if pixel is back-facing.
	depthStencilDesc.BackFace.StencilFailOp = D3D11_STENCIL_OP_KEEP;
	depthStencilDesc.BackFace.StencilDepthFailOp = D3D11_STENCIL_OP_DECR;
	depthStencilDesc.BackFace.StencilPassOp = D3D11_STENCIL_OP_KEEP;
	depthStencilDesc.BackFace.StencilFunc = D3D11_COMPARISON_ALWAYS;

	// Create the depth stencil state.
	result = m_device->CreateDepthStencilState(&depthStencilDesc, &m_depthStencilState);
	if(FAILED(result))
	{
		return false;
	}

	// Set the depth stencil state.
	m_deviceContext->OMSetDepthStencilState(m_depthStencilState, 1);

	// Initialize the depth stencil view.
	ZeroMemory(&depthStencilViewDesc, sizeof(depthStencilViewDesc));

	// Set up the depth stencil view description.
	depthStencilViewDesc.Format = DXGI_FORMAT_D24_UNORM_S8_UINT;
	depthStencilViewDesc.ViewDimension = D3D11_DSV_DIMENSION_TEXTURE2D;
	depthStencilViewDesc.Texture2D.MipSlice = 0;

	// Create the depth stencil view.
	result = m_device->CreateDepthStencilView(m_depthStencilBuffer, &depthStencilViewDesc, &m_depthStencilView);
	if(FAILED(result))
	{
		return false;
	}

	// Bind the render target view and depth stencil buffer to the output render pipeline.
	m_deviceContext->OMSetRenderTargets(1, &m_renderTargetView, m_depthStencilView);

	// Setup the raster description which will determine how and what polygons will be drawn.
	rasterDesc.AntialiasedLineEnable = false;
	rasterDesc.CullMode = D3D11_CULL_BACK;
	rasterDesc.DepthBias = 0;
	rasterDesc.DepthBiasClamp = 0.0f;
	rasterDesc.DepthClipEnable = true;
	rasterDesc.FillMode = D3D11_FILL_SOLID;
	rasterDesc.FrontCounterClockwise = false;
	rasterDesc.MultisampleEnable = false;
	rasterDesc.ScissorEnable = false;
	rasterDesc.SlopeScaledDepthBias = 0.0f;

	// Create the rasterizer state from the description we just filled out.
	result = m_device->CreateRasterizerState(&rasterDesc, &m_rasterState);
	if(FAILED(result))
	{
		return false;
	}

	// Now set the rasterizer state.
	m_deviceContext->RSSetState(m_rasterState);
	
	// Setup the viewport for rendering.
	viewport.Width = (float)screenWidth;
	viewport.Height = (float)screenHeight;
	viewport.MinDepth = 0.0f;
	viewport.MaxDepth = 1.0f;
	viewport.TopLeftX = 0.0f;
	viewport.TopLeftY = 0.0f;

	// Create the viewport.
	m_deviceContext->RSSetViewports(1, &viewport);

	// Setup the projection matrix.
	fieldOfView = (float)D3DX_PI / 4.0f;
	screenAspect = (float)screenWidth / (float)screenHeight;

	// Create the projection matrix for 3D rendering.
	D3DXMatrixPerspectiveFovLH(&m_projectionMatrix, fieldOfView, screenAspect, screenNear, screenDepth);

	// Initialize the world matrix to the identity matrix.
	D3DXMatrixIdentity(&m_worldMatrix);

	// Create an orthographic projection matrix for 2D rendering.
	D3DXMatrixOrthoLH(&m_orthoMatrix, (float)screenWidth, (float)screenHeight, screenNear, screenDepth);

在这里我们设置深度模板的描述。注意，这个新的深度模板与旧的深度模板唯一的区别在于，这里将 DepthEnable 设置为 false 以进行 2D 绘制。

	// Clear the second depth stencil state before setting the parameters.
	ZeroMemory(&depthDisabledStencilDesc, sizeof(depthDisabledStencilDesc));

	// Now create a second depth stencil state which turns off the Z buffer for 2D rendering.  The only difference is 
	// that DepthEnable is set to false, all other parameters are the same as the other depth stencil state.
	depthDisabledStencilDesc.DepthEnable = false;
	depthDisabledStencilDesc.DepthWriteMask = D3D11_DEPTH_WRITE_MASK_ALL;
	depthDisabledStencilDesc.DepthFunc = D3D11_COMPARISON_LESS;
	depthDisabledStencilDesc.StencilEnable = true;
	depthDisabledStencilDesc.StencilReadMask = 0xFF;
	depthDisabledStencilDesc.StencilWriteMask = 0xFF;
	depthDisabledStencilDesc.FrontFace.StencilFailOp = D3D11_STENCIL_OP_KEEP;
	depthDisabledStencilDesc.FrontFace.StencilDepthFailOp = D3D11_STENCIL_OP_INCR;
	depthDisabledStencilDesc.FrontFace.StencilPassOp = D3D11_STENCIL_OP_KEEP;
	depthDisabledStencilDesc.FrontFace.StencilFunc = D3D11_COMPARISON_ALWAYS;
	depthDisabledStencilDesc.BackFace.StencilFailOp = D3D11_STENCIL_OP_KEEP;
	depthDisabledStencilDesc.BackFace.StencilDepthFailOp = D3D11_STENCIL_OP_DECR;
	depthDisabledStencilDesc.BackFace.StencilPassOp = D3D11_STENCIL_OP_KEEP;
	depthDisabledStencilDesc.BackFace.StencilFunc = D3D11_COMPARISON_ALWAYS;

现在创建新的深度模板。

	// Create the state using the device.
	result = m_device->CreateDepthStencilState(&depthDisabledStencilDesc, &m_depthDisabledStencilState);
	if(FAILED(result))
	{
		return false;
	}

	return true;
}

void D3DClass::Shutdown()
{
	// Before shutting down set to windowed mode or when you release the swap chain it will throw an exception.
	if(m_swapChain)
	{
		m_swapChain->SetFullscreenState(false, NULL);
	}

这里我们在 Shutdown 函数中释放新的深度模板。

	if(m_depthDisabledStencilState)
	{
		m_depthDisabledStencilState->Release();
		m_depthDisabledStencilState = 0;
	}

	if(m_rasterState)
	{
		m_rasterState->Release();
		m_rasterState = 0;
	}

	if(m_depthStencilView)
	{
		m_depthStencilView->Release();
		m_depthStencilView = 0;
	}

	if(m_depthStencilState)
	{
		m_depthStencilState->Release();
		m_depthStencilState = 0;
	}

	if(m_depthStencilBuffer)
	{
		m_depthStencilBuffer->Release();
		m_depthStencilBuffer = 0;
	}

	if(m_renderTargetView)
	{
		m_renderTargetView->Release();
		m_renderTargetView = 0;
	}

	if(m_deviceContext)
	{
		m_deviceContext->Release();
		m_deviceContext = 0;
	}

	if(m_device)
	{
		m_device->Release();
		m_device = 0;
	}

	if(m_swapChain)
	{
		m_swapChain->Release();
		m_swapChain = 0;
	}

	return;
}

void D3DClass::BeginScene(float red, float green, float blue, float alpha)
{
	float color[4];

	// Setup the color to clear the buffer to.
	color[0] = red;
	color[1] = green;
	color[2] = blue;
	color[3] = alpha;

	// Clear the back buffer.
	m_deviceContext->ClearRenderTargetView(m_renderTargetView, color);
    
	// Clear the depth buffer.
	m_deviceContext->ClearDepthStencilView(m_depthStencilView, D3D11_CLEAR_DEPTH, 1.0f, 0);

	return;
}

void D3DClass::EndScene()
{
	// Present the back buffer to the screen since rendering is complete.
	if(m_vsync_enabled)
	{
		// Lock to screen refresh rate.
		m_swapChain->Present(1, 0);
	}
	else
	{
		// Present as fast as possible.
		m_swapChain->Present(0, 0);
	}

	return;
}

ID3D11Device* D3DClass::GetDevice()
{
	return m_device;
}

ID3D11DeviceContext* D3DClass::GetDeviceContext()
{
	return m_deviceContext;
}

void D3DClass::GetProjectionMatrix(D3DXMATRIX& projectionMatrix)
{
	projectionMatrix = m_projectionMatrix;
	return;
}

void D3DClass::GetWorldMatrix(D3DXMATRIX& worldMatrix)
{
	worldMatrix = m_worldMatrix;
	return;
}

void D3DClass::GetOrthoMatrix(D3DXMATRIX& orthoMatrix)
{
	orthoMatrix = m_orthoMatrix;
	return;
}

void D3DClass::GetVideoCardInfo(char* cardName, int& memory)
{
	strcpy_s(cardName, 128, m_videoCardDescription);
	memory = m_videoCardMemory;
	return;
}

这些是启用和禁用 Z 缓冲区的新函数。要打开 Z 缓冲区，我们设置原始的深度模板。要关闭 Z 缓冲区，我们设置新的深度模板，该模板将 depthEnable 设置为 false。通常，使用这些函数的最佳方法是先进行所有 3D 渲染，然后关闭 Z 缓冲区并进行 2D 渲染，然后再次打开 Z 缓冲区。

void D3DClass::TurnZBufferOn()
{
	m_deviceContext->OMSetDepthStencilState(m_depthStencilState, 1);
	return;
}

void D3DClass::TurnZBufferOff()
{
	m_deviceContext->OMSetDepthStencilState(m_depthDisabledStencilState, 1);
	return;
}

Graphicsclass.h

////////////////////////////////////////////////////////////////////////////////
// Filename: graphicsclass.h
////////////////////////////////////////////////////////////////////////////////
#ifndef _GRAPHICSCLASS_H_
#define _GRAPHICSCLASS_H_

///////////////////////
// MY CLASS INCLUDES //
///////////////////////
#include "d3dclass.h"
#include "cameraclass.h"
#include "textureshaderclass.h"

这里我们包含新的 BitmapClass 头文件。

#include "bitmapclass.h"

/////////////
// GLOBALS //
/////////////
const bool FULL_SCREEN = true;
const bool VSYNC_ENABLED = true;
const float SCREEN_DEPTH = 1000.0f;
const float SCREEN_NEAR = 0.1f;

////////////////////////////////////////////////////////////////////////////////
// Class name: GraphicsClass
////////////////////////////////////////////////////////////////////////////////
class GraphicsClass
{
public:
	GraphicsClass();
	GraphicsClass(const GraphicsClass&);
	~GraphicsClass();

	bool Initialize(int, int, HWND);
	void Shutdown();
	bool Frame();

private:
	bool Render(float);

private:
	D3DClass* m_D3D;
	CameraClass* m_Camera;
	TextureShaderClass* m_TextureShader;

我们在这里创建一个新的私有 BitmapClass 对象。

	BitmapClass* m_Bitmap;

};

#endif

Graphicsclass.cpp

////////////////////////////////////////////////////////////////////////////////
// Filename: graphicsclass.cpp
////////////////////////////////////////////////////////////////////////////////
#include "graphicsclass.h"

GraphicsClass::GraphicsClass()
{
	m_D3D = 0;
	m_Camera = 0;
	m_TextureShader = 0;

我们在类构造函数中将新的位图对象初始化为 null。

	m_Bitmap = 0;

}

GraphicsClass::GraphicsClass(const GraphicsClass& other)
{
}

GraphicsClass::~GraphicsClass()
{
}

bool GraphicsClass::Initialize(int screenWidth, int screenHeight, HWND hwnd)
{
	bool result;

	// Create the Direct3D object.
	m_D3D = new D3DClass;
	if(!m_D3D)
	{
		return false;
	}

	// Initialize the Direct3D object.
	result = m_D3D->Initialize(screenWidth, screenHeight, VSYNC_ENABLED, hwnd, FULL_SCREEN, SCREEN_DEPTH, SCREEN_NEAR);
	if(!result)
	{
		MessageBox(hwnd, L"Could not initialize Direct3D.", L"Error", MB_OK);
		return false;
	}

	// Create the camera object.
	m_Camera = new CameraClass;
	if(!m_Camera)
	{
		return false;
	}

	// Set the initial position of the camera.
	m_Camera->SetPosition(0.0f, 0.0f, -10.0f);
	
	// Create the texture shader object.
	m_TextureShader = new TextureShaderClass;
	if(!m_TextureShader)
	{
		return false;
	}

	// Initialize the texture shader object.
	result = m_TextureShader->Initialize(m_D3D->GetDevice(), hwnd);
	if(!result)
	{
		MessageBox(hwnd, L"Could not initialize the texture shader object.", L"Error", MB_OK);
		return false;
	}

这里我们创建并初始化新的 BitmapClass 对象。它使用 seafloor.dds 作为纹理，我将大小设置为 256x256。您可以将此大小更改为您喜欢的任何大小，因为它不需要反映纹理的精确大小。

	// Create the bitmap object.
	m_Bitmap = new BitmapClass;
	if(!m_Bitmap)
	{
		return false;
	}

	// Initialize the bitmap object.
	result = m_Bitmap->Initialize(m_D3D->GetDevice(), screenWidth, screenHeight, L"../Engine/data/seafloor.dds", 256, 256);
	if(!result)
	{
		MessageBox(hwnd, L"Could not initialize the bitmap object.", L"Error", MB_OK);
		return false;
	}

	return true;
}

void GraphicsClass::Shutdown()
{

BitmapClass 对象在 Shutdown 函数中被释放。

	// Release the bitmap object.
	if(m_Bitmap)
	{
		m_Bitmap->Shutdown();
		delete m_Bitmap;
		m_Bitmap = 0;
	}

	// Release the texture shader object.
	if(m_TextureShader)
	{
		m_TextureShader->Shutdown();
		delete m_TextureShader;
		m_TextureShader = 0;
	}

	// Release the camera object.
	if(m_Camera)
	{
		delete m_Camera;
		m_Camera = 0;
	}

	// Release the D3D object.
	if(m_D3D)
	{
		m_D3D->Shutdown();
		delete m_D3D;
		m_D3D = 0;
	}

	return;
}

bool GraphicsClass::Frame()
{
	bool result;
	static float rotation = 0.0f;

	// Update the rotation variable each frame.
	rotation += (float)D3DX_PI * 0.005f;
	if(rotation > 360.0f)
	{
		rotation -= 360.0f;
	}
	
	// Render the graphics scene.
	result = Render(rotation);
	if(!result)
	{
		return false;
	}

	return true;
}

bool GraphicsClass::Render(float rotation)
{

	D3DXMATRIX worldMatrix, viewMatrix, projectionMatrix, orthoMatrix;

	bool result;

	// Clear the buffers to begin the scene.
	m_D3D->BeginScene(0.0f, 0.0f, 0.0f, 1.0f);

	// Generate the view matrix based on the camera's position.
	m_Camera->Render();

	// Get the world, view, projection, and ortho matrices from the camera and d3d objects.
	m_Camera->GetViewMatrix(viewMatrix);
	m_D3D->GetWorldMatrix(worldMatrix);
	m_D3D->GetProjectionMatrix(projectionMatrix);

我们现在还从 D3DClass 获取正交矩阵以进行 2D 渲染。我们将传入此矩阵而不是投影矩阵。

	m_D3D->GetOrthoMatrix(orthoMatrix);

在进行任何 2D 渲染之前，Z 缓冲区将被关闭。

	// Turn off the Z buffer to begin all 2D rendering.
	m_D3D->TurnZBufferOff();

然后我们将位图渲染到屏幕上的 100, 100 位置。您可以将其更改为要渲染的任何位置。

	// Put the bitmap vertex and index buffers on the graphics pipeline to prepare them for drawing.
	result = m_Bitmap->Render(m_D3D->GetDeviceContext(), 100, 100);
	if(!result)
	{
		return false;
	}

一旦顶点/索引缓冲区准备好，我们使用纹理着色器绘制它们。请注意，我们在渲染 2D 时传入 orthoMatrix 而不是 projectionMatrix。另请注意，如果您的视图矩阵正在发生变化，您将需要为 2D 渲染创建一个默认的视图矩阵，并使用它而不是常规的视图矩阵。在本教程中，使用常规的视图矩阵是可以的，因为本教程中的相机是静止的。

	// Render the bitmap with the texture shader.
	result = m_TextureShader->Render(m_D3D->GetDeviceContext(), m_Bitmap->GetIndexCount(), worldMatrix, viewMatrix, orthoMatrix, m_Bitmap->GetTexture());
	if(!result)
	{
		return false;
	}

完成所有 2D 渲染后，我们将打开 Z 缓冲区以进行下一轮 3D 渲染。

	// Turn the Z buffer back on now that all 2D rendering has completed.
	m_D3D->TurnZBufferOn();

	// Present the rendered scene to the screen.
	m_D3D->EndScene();

	return true;
}

总结

有了这些新概念，我们现在可以将 2D 图像渲染到屏幕上。这为渲染用户界面和字体系统打开了大门。

待办事项

1. 重新编译代码，并确保您在屏幕上的 100, 100 位置绘制了 2D 图像。

2. 更改屏幕上图像绘制的位置。

3. 更改 GraphicsClass 中 m_Bitmap->Initialize 函数调用中的图像大小。

4. 更改用于 2D 图像的纹理。