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：
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：
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。
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。
文件下载（已下载 1492 次）发布时间：2012/7/20 下午4:26:16 阅读次数：13546
