DirectX 10 教程11:绘制2D图像

原文地址:Tutorial 11: 2D Rendering(http://www.rastertek.com/dx10tut11.html) 。

源代码:dx10tut11.zip

绘制2D图像是非常有用的。例如,大多数用户界面,sprite系统和文字引擎都是由2D图像构成的。DirectX 10通过将2D图像映射到多边形和使用正交投影矩阵绘制实现了2D图像的绘制。

 2D屏幕坐标

要将2D图像绘制到屏幕上需要计算屏幕的X和Y坐标。DirectX中屏幕中点的坐标为0,0。屏幕左边和下边的坐标为负方向,右边和上边的坐标为正方形。例如屏幕分辨率为1024x768,则边框的坐标如下图所示:

2D屏幕坐标

所以,2D绘制需要处理这种屏幕坐标计算,你还需要屏幕大小信息用于将2D图像正确地放置到屏幕上。

在DirectX 10中关闭Z缓存

要绘制2D必须关闭Z缓存。关闭Z缓存后,2D数据就会覆盖在当前像素的顶部。2D绘制使用的是画家算法,从后向前绘制。完成2D图像的绘制后还需要重新打开Z缓存,这样才可以正确地绘制3D图像。

要能开启关闭Z缓存,你需要创建第二个深度模板状态,这个状态与3D场景中使用状态唯一的区别在于DepthEnable设置为false。然后使用OMSetDepthStencilState在两个状态之间切换实现Z缓存的开启和闭合。

动态顶点缓存

还需要介绍的一个新概念是动态顶点缓存。在前面的教程中我们使用的都是静态顶点缓存。静态顶点缓存的特点是你无法修改缓存中的数据,而动态顶点缓存可以让你在需要的时候修改缓存中的数据。动态缓存要比静态缓存慢得多,但可以实现一些特殊的功能。

我在2D绘制中使用动态缓存的原因是我们经常需要将2D图像移动到屏幕的不同位置。例如光标,它经常在移动,因此表示这个位置的顶点数据经常会发生改变。

有两点需要注意。第一,除非你确定需要,否则不要使用动态顶点缓存,它们要比静态缓存慢。第二,不要在每帧重复清除和创建静态缓存,它会锁定显卡(我在ATI显卡上遇到过这种情况,但Nvidia上没有),会比使用动态顶点缓存性能更糟。

DirectX 10中的正交投影

最后一个新概念是使用正交投影矩阵代替常规的3D投影矩阵。这样才能在2D屏幕坐标中进行绘制。我们已经在Direct3D的初始化代码中创建了这个矩阵:

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

框架

本教程基于上一个教程的代码。主要的不同在于ModelClass类被BitmapClass类替代,我们再次使用了TextureShaderClass替换了LightShaderClass。结构如下图所示:

框架

Bitmapclass.h

BitmapClass表示要绘制的2D图像。每个2D图像都需要一个新的BitmapClass对象。注意这个类实际上只是ModelClass的重写,不过处理的是2D图像而不是3D模型。

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


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


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

每张位图实际上还是一个多边形对象,绘制方式与3D对象类似。对于2D图像来说,需要位置矢量和纹理坐标的信息。

	struct VertexType
	{
		D3DXVECTOR3 position;
	    D3DXVECTOR2 texture;
	};

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

	bool Initialize(ID3D10Device*, int, int, WCHAR*, int, int);
	void Shutdown();
	bool Render(ID3D10Device*, int, int);

	int GetIndexCount();
	ID3D10ShaderResourceView* GetTexture();

private:
	bool InitializeBuffers(ID3D10Device*);
	void ShutdownBuffers();
	bool UpdateBuffers(int, int);
	void RenderBuffers(ID3D10Device*);

	bool LoadTexture(ID3D10Device*, WCHAR*);
	void ReleaseTexture();

private:
	ID3D10Buffer *m_vertexBuffer, *m_indexBuffer;
	int m_vertexCount, m_indexCount;
	TextureClass* m_Texture;

BitmapClass需要保存一些3D对象不需要的额外信息,这些信息包括屏幕大小,位图大小,最近一次绘制时的位置,这些信息都保存在下面的私有变量中。

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

#endif

Bitmapclass.cpp

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

构造函数中将所有私有指针初始化为null。

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


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


BitmapClass::~BitmapClass()
{
}


bool BitmapClass::Initialize(ID3D10Device* device, int screenWidth, int screenHeight, WCHAR* textureFilename, int bitmapWidth, int bitmapHeight)
{
	bool result;

在Initialize方法中保存了屏幕大小和图形大小,这些信息用于在绘制时生成正确的顶点位置。注意图像的大小不需要与纹理相同,你可以设置使用任意大小的纹理。

	// 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;

前一帧绘制的位置首先初始化为-1,这是个重要的值。如果图像位置没有发生改变,我们就无需更新动态顶点缓存,可以节省处理时间。

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

	// Initialize the vertex and index buffer that hold the geometry for the triangle.
	result = InitializeBuffers(device);
	if(!result)
	{
		return false;
	}

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

	return true;
}

Shutdown方法释放顶点缓存、索引缓存和纹理。

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

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

	return;
}

Render将2D图像的缓存传递到显卡,参数是图像的屏幕坐标。UpdateBuffers方法的参数为屏幕坐标,如果坐标发生改变,就将动态缓存中的顶点位置更新为新的值。之后RenderBuffers方法准备最终的顶点/索引进行绘制。

bool BitmapClass::Render(ID3D10Device* device, int positionX, int positionY)
{
	bool result;


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

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

	return true;
}

GetIndexCount方法返回2D图像的索引数量,非常简单,它总是6。

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

GetTexture方法返回纹理资源的指针,shader会调用这个方法使之可以访问图像。

ID3D10ShaderResourceView* BitmapClass::GetTexture()
{
	return m_Texture->GetTexture();
}

InitializeBuffers方法用于创建顶点和索引缓存。

bool BitmapClass::InitializeBuffers(ID3D10Device* device)
{
	VertexType* vertices;
	unsigned long* indices;
	D3D10_BUFFER_DESC vertexBufferDesc, indexBufferDesc;
    D3D10_SUBRESOURCE_DATA vertexData, indexData;
	HRESULT result;
	int i;

因为一个矩形由两个三角形构成,所以顶点数量设置为6,索引也是6。

	// 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;
	}

下面的代码是与ModelClass最大的区别。我们现在创建的是动态顶点缓存,因此可以在每帧必要时修改顶点缓存中的数据。需要将Usage设置为D3D10_USAGE_DYNAMIC,CPUAccessFlags设置为D3D10_CPU_ACCESS_WRITE。

	// Set up the description of the dynamic vertex buffer.
    vertexBufferDesc.Usage = D3D10_USAGE_DYNAMIC;
    vertexBufferDesc.ByteWidth = sizeof(VertexType) * m_vertexCount;
    vertexBufferDesc.BindFlags = D3D10_BIND_VERTEX_BUFFER;
    vertexBufferDesc.CPUAccessFlags = D3D10_CPU_ACCESS_WRITE;
    vertexBufferDesc.MiscFlags = 0;

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

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

索引缓存无需设置为动态,因为六个索引总是指向相同的六个顶点,虽然顶点的坐标可能发生变化。

	// Set up the description of the index buffer.
    indexBufferDesc.Usage = D3D10_USAGE_DEFAULT;
    indexBufferDesc.ByteWidth = sizeof(unsigned long) * m_indexCount;
    indexBufferDesc.BindFlags = D3D10_BIND_INDEX_BUFFER;
    indexBufferDesc.CPUAccessFlags = 0;
    indexBufferDesc.MiscFlags = 0;

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

	// 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;
}
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;
}

每帧都要调用UpdateBuffers方法更新动态顶点缓存中的内容,使图像在屏幕上的位置发生改变。

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

我们检查位置是否发生变化。如果不变则无需修改顶点缓存,这个检查可以帮助我们节省大量的处理时间。

	// 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;
	}

如果位置发生改变则需要保存这个新位置用于下次的检查。

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

需要计算图像四个顶点的位置。你可以参见教程一开始的图理解计算的原理。

	// 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;

计算好顶点坐标后,就可以创建一个临时顶点数组,然后将这六个顶点位置填充到这个数组中。

	// 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);

使用Map和memcpy方法将顶点数组的内容复制到顶点缓存中。

	// Initialize the vertex buffer pointer to null first.
	verticesPtr = 0;

	// Lock the vertex buffer.
	result = m_vertexBuffer->Map(D3D10_MAP_WRITE_DISCARD, 0, (void**)&verticesPtr);
	if(FAILED(result))
	{
		return false;
	}

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

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

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

	return true;
}

RenderBuffers方法设置顶点缓存和索引缓存。

void BitmapClass::RenderBuffers(ID3D10Device* device)
{
	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.
	device->IASetVertexBuffers(0, 1, &m_vertexBuffer, &stride, &offset);

    // Set the index buffer to active in the input assembler so it can be rendered.
    device->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.
    device->IASetPrimitiveTopology(D3D10_PRIMITIVE_TOPOLOGY_TRIANGLELIST);

	return;
}

下面的方法加载纹理。

bool BitmapClass::LoadTexture(ID3D10Device* 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;
}

ReleaseTexture方法释放纹理。

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

	return;
}

D3dclass.h

D3Dclass需要进行修改,添加开启和关闭Z缓存的代码。

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


/////////////
// LINKING //
/////////////
#pragma comment(lib, "d3d10.lib")
#pragma comment(lib, "d3dx10.lib")
#pragma comment(lib, "dxgi.lib")


//////////////
// INCLUDES //
//////////////
#include <d3d10.h>
#include <d3dx10.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();

	ID3D10Device* GetDevice();

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

	void GetVideoCardInfo(char*, int&);

我们需要两个新方法开启和关闭Z缓存。

	void TurnZBufferOn();
	void TurnZBufferOff();

private:
	bool m_vsync_enabled;
	int m_videoCardMemory;
	char m_videoCardDescription[128];
	IDXGISwapChain* m_swapChain;
	ID3D10Device* m_device;
	ID3D10RenderTargetView* m_renderTargetView;
	ID3D10Texture2D* m_depthStencilBuffer;
	ID3D10DepthStencilState* m_depthStencilState;
	ID3D10DepthStencilView* m_depthStencilView;
	ID3D10RasterizerState* m_rasterState;
	D3DXMATRIX m_projectionMatrix;
	D3DXMATRIX m_worldMatrix;
	D3DXMATRIX m_orthoMatrix;

还需要一个新的深度模板状态用于2D绘制。

	ID3D10DepthStencilState* m_depthDisabledStencilState;
};

#endif

D3dclass.cpp

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


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

在构造函数中将新的深度模板状态设置为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;
	ID3D10Texture2D* backBufferPtr;
	D3D10_TEXTURE2D_DESC depthBufferDesc;
	D3D10_DEPTH_STENCIL_DESC depthStencilDesc;
	D3D10_DEPTH_STENCIL_VIEW_DESC depthStencilViewDesc;
	D3D10_VIEWPORT viewport;
	float fieldOfView, screenAspect;
	D3D10_RASTERIZER_DESC rasterDesc;

需要一个新的深度模板描述变量用于创建深度模板。

	D3D10_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;

	// Create the swap chain and the Direct3D device.
	result = D3D10CreateDeviceAndSwapChain(NULL, D3D10_DRIVER_TYPE_HARDWARE, NULL, 0, D3D10_SDK_VERSION, &swapChainDesc, &m_swapChain, &m_device);
	if(FAILED(result))
	{
		return false;
	}

	// Get the pointer to the back buffer.
	result = m_swapChain->GetBuffer(0, __uuidof(ID3D10Texture2D), (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 = D3D10_USAGE_DEFAULT;
	depthBufferDesc.BindFlags = D3D10_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 = D3D10_DEPTH_WRITE_MASK_ALL;
	depthStencilDesc.DepthFunc = D3D10_COMPARISON_LESS;

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

	// Stencil operations if pixel is front-facing.
	depthStencilDesc.FrontFace.StencilFailOp = D3D10_STENCIL_OP_KEEP;
	depthStencilDesc.FrontFace.StencilDepthFailOp = D3D10_STENCIL_OP_INCR;
	depthStencilDesc.FrontFace.StencilPassOp = D3D10_STENCIL_OP_KEEP;
	depthStencilDesc.FrontFace.StencilFunc = D3D10_COMPARISON_ALWAYS;

	// Stencil operations if pixel is back-facing.
	depthStencilDesc.BackFace.StencilFailOp = D3D10_STENCIL_OP_KEEP;
	depthStencilDesc.BackFace.StencilDepthFailOp = D3D10_STENCIL_OP_DECR;
	depthStencilDesc.BackFace.StencilPassOp = D3D10_STENCIL_OP_KEEP;
	depthStencilDesc.BackFace.StencilFunc = D3D10_COMPARISON_ALWAYS;

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

	// Set the depth stencil state on the D3D device.
	m_device->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 = D3D10_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_device->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 = D3D10_CULL_BACK;
	rasterDesc.DepthBias = 0;
	rasterDesc.DepthBiasClamp = 0.0f;
	rasterDesc.DepthClipEnable = true;
	rasterDesc.FillMode = D3D10_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_device->RSSetState(m_rasterState);

	// Setup the viewport for rendering.
    viewport.Width = screenWidth;
    viewport.Height = screenHeight;
    viewport.MinDepth = 0.0f;
    viewport.MaxDepth = 1.0f;
    viewport.TopLeftX = 0;
    viewport.TopLeftY = 0;

	// Create the viewport.
    m_device->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);

下面的代码中我们创建了深度模板描述。这个新描述与旧描述唯一的不同就是DepthEnable被设置为false。

	// 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 = D3D10_DEPTH_WRITE_MASK_ALL;
	depthDisabledStencilDesc.DepthFunc = D3D10_COMPARISON_LESS;
	depthDisabledStencilDesc.StencilEnable = true;
	depthDisabledStencilDesc.StencilReadMask = 0xFF;
	depthDisabledStencilDesc.StencilWriteMask = 0xFF;
	depthDisabledStencilDesc.FrontFace.StencilFailOp = D3D10_STENCIL_OP_KEEP;
	depthDisabledStencilDesc.FrontFace.StencilDepthFailOp = D3D10_STENCIL_OP_INCR;
	depthDisabledStencilDesc.FrontFace.StencilPassOp = D3D10_STENCIL_OP_KEEP;
	depthDisabledStencilDesc.FrontFace.StencilFunc = D3D10_COMPARISON_ALWAYS;
	depthDisabledStencilDesc.BackFace.StencilFailOp = D3D10_STENCIL_OP_KEEP;
	depthDisabledStencilDesc.BackFace.StencilDepthFailOp = D3D10_STENCIL_OP_DECR;
	depthDisabledStencilDesc.BackFace.StencilPassOp = D3D10_STENCIL_OP_KEEP;
	depthDisabledStencilDesc.BackFace.StencilFunc = D3D10_COMPARISON_ALWAYS;

现在就可以创建新深度模板了。

	// 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);
	}

在Shutdown方法中释放新深度模板。

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

	if(m_device)
	{
		m_device->Release();
		m_device = 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_device->ClearRenderTargetView(m_renderTargetView, color);
    
	// Clear the depth buffer.
	m_device->ClearDepthStencilView(m_depthStencilView, D3D10_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;
}


ID3D10Device* D3DClass::GetDevice()
{
	return m_device;
}


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;
}

下面的新方法用于开启和关闭Z缓存。要开启Z缓存只需设置原始的深度模板,要关闭Z缓存设置的是新深度模板。通常使用的最好方式就是先绘制3D内容,然后关闭Z缓存进行2D绘制,接着再把Z缓存打开。

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


void D3DClass::TurnZBufferOff()
{
	m_device->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"

头文件中包含了新的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;

在这里创建新的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;

在构造函数中将bitmap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;
	}

下面的代码创建并初始化BitmapClass对象。使用的纹理为seafloor.dds,大小为256x256。这个大小可以设置为任何值,而无需与纹理的实际大小相同。

	// 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()
{

在Shutdown方法中释放BitmapClass对象。

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

下面的代码从D3Dclass中获取正交投影矩阵用于2D绘制,使用这个正交投影矩阵代替前面教程中的投影矩阵。

	m_D3D->GetOrthoMatrix(orthoMatrix);

在绘制2D内容之前需要关闭Z buffer缓存。

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

然后将图像绘制在屏幕的100, 100位置。

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

准备好顶点/索引缓存后就可以使用texture shader进行绘制了。注意在绘制2D时我们使用的是正交投影矩阵。第二个要注意的是如果视矩阵会发生改变的话,你需要创建一个新的针对2D绘制的视矩阵。而本教程中相机是不动的,所以你使用的就是默认的视矩阵。

	// Render the bitmap using the texture shader.
	m_TextureShader->Render(m_D3D->GetDevice(), m_Bitmap->GetIndexCount(), worldMatrix, viewMatrix, orthoMatrix, m_Bitmap->GetTexture());

	// 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

现在我们就可以在屏幕上绘制2D图像了,在此基础上我们还可以实现用户界面和字体系统。

程序截图

练习

1.编译代码在屏幕的100,100位置绘制一张2D图像。

2.改变图像的位置。

3.在GraphicsClass中的m_Bitmap->Initialize方法中改变图像的大小。

4.改变用于2D图像的纹理。

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发布时间:2012/7/20 16:26:16  阅读次数:12823

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