在 directx 9 中画一个圆
Drawing a circle in directx 9
我很难弄清楚如何在directx中画一个圆。我能够画一个三角形，所以我想象我可以通过将三角形旋转成一个圆来画一个三角形。但是，我完全被难住了。我已经在网上搜索了几个小时，但没有运气。谁能帮我？这是我的代码：
主.cpp
#include "Engine.h"
#include "Box2D.h"
#include "Triangle2D.h"
class MyApp : public Engine {
public:
Box2D box2D;
Triangle2D triangle2D;
void OnStartup() override {
box2D.New(10.0f, 10.0f, 100.0f, 100.0f, D3DCOLOR_ARGB(0xff, 0x00, 0x00, 0xff));
triangle2D.New(150.0f, 10.0f, 100.0f, 100.0f, D3DCOLOR_ARGB(0xff, 0xff, 0x00, 0x00));
}
void OnShutdown() override {
box2D.Delete();
triangle2D.Delete();
}
void OnDraw() override {
box2D.Draw();
triangle2D.Draw();
}
void OnMouseDown(int x, int y) {
Debug("%d %dn", x, y);
}
};
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
MyApp app;
app.Run();
return 0;
}
引擎.cpp
#include "Engine.h"
// Initialize the classes static variables
Engine* Engine::_ENGINE = NULL;
// Returns the current instance of this class
Engine* Engine::GetInstance()
{
return _ENGINE;
}
// Constructor
Engine::Engine()
: _exit(false)
, _window(NULL)
, _directx(NULL)
, _device(NULL)
{
_ENGINE = this;
}
// Deconstructor
Engine::~Engine() {
_ENGINE = NULL;
}
// Run the core main event loop, start to finish
bool Engine::Run() {
// Create the Windows class
WNDCLASSEX wc;
ZeroMemory(&wc, sizeof(wc));
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = CS_VREDRAW | CS_HREDRAW | CS_DBLCLKS | CS_CLASSDC;
wc.lpfnWndProc = _WND_PROC;
wc.hInstance = GetModuleHandle(NULL);
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
wc.lpszClassName = _GetModuleName();
RegisterClassEx(&wc);
// Adjust the window rect for the flags
RECT rect;
SetRect(&rect, 0, 0, _WIDTH, _HEIGHT);
const DWORD windowFlags = WS_OVERLAPPED | WS_CAPTION | WS_CLIPCHILDREN | WS_SYSMENU | WS_MINIMIZEBOX;
AdjustWindowRectEx(&rect, windowFlags, FALSE, 0);
// Create the window
_window = CreateWindowEx(0, _GetModuleName(), _GetModuleName(), windowFlags, 0, 0, rect.right - rect.left, rect.bottom - rect.top, NULL, NULL, GetModuleHandle(NULL), NULL);
if (_window == NULL)
return false;
// Move the window to the center of the screen
RECT system;
SystemParametersInfo(SPI_GETWORKAREA, 0, &system, 0);
MoveWindow(_window, (system.right - system.left) / 2 - (rect.right - rect.left) / 2, (system.bottom - system.top) / 2 - (rect.bottom - rect.top) / 2, rect.right - rect.left, rect.bottom - rect.top, TRUE);
// Startup Direct X
if (_DirectXStartup() == false)
return false;
// Call our startup callback
OnStartup();
// Show the window
ShowWindow(_window, SW_SHOWNORMAL);
// Run the event loop
MSG msg;
ULONGLONG timer = GetTickCount64();
while (!_exit) {
// Handle normal system events
if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
// Run the timer at the framerate
if (timer + 1000 / _FPS < GetTickCount64()) {
timer = GetTickCount64();
// Clear the buffer
_device->Clear(0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, D3DCOLOR_XRGB(0x00, 0xff, 0x00), 1.0f, NULL);
// Call our draw callback every frame
OnDraw();
// Render to screen
_device->Present(NULL, NULL, NULL, NULL);
}
}
// Hide the window to avoid flicker
ShowWindow(_window, SW_HIDE);
// Call our shutdown callback
OnShutdown();
// Shutdown Direct X
_DirectXShutdown();
// Cleanup and destroy the window
DestroyWindow(_window);
UnregisterClass(_GetModuleName(), GetModuleHandle(NULL));
return true;
}
// Return the DirectX device, needed by other DirectX objects
LPDIRECT3DDEVICE9 Engine::GetDevice() {
return _device;
}
// Return our width
int Engine::GetWidth() {
return _WIDTH;
}
// Return our height
int Engine::GetHeight() {
return _HEIGHT;
}
// Our own custom debug string
void Engine::Debug(const char* message, ...) {
#if _DEBUG
if (message) {
va_list args;
va_start(args, message);
int size = vsnprintf(NULL, 0, message, args);
if (size > 0) {
char* string = new char[size + 1];
vsnprintf(string, size + 1, message, args);
OutputDebugStringA(string);
delete[] string;
}
va_end(args);
}
#endif
}
// This is the Windows callback
LRESULT CALLBACK Engine::_WND_PROC(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
// If we do not have access to an instance of our engine, do nothing
if (Engine::_ENGINE == NULL)
return DefWindowProc(hwnd, uMsg, wParam, lParam);
// Handle system messages
switch (uMsg) {
case WM_LBUTTONDOWN:
Engine::_ENGINE->OnMouseDown(GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam));
return 0;
case WM_KEYDOWN:
case WM_SYSKEYDOWN:
if ((lParam & (1 << 30)) == 0)
Engine::_ENGINE->OnKeyDown((int)wParam);
return 0;
case WM_CHAR:
if ((int)wParam <= 127 && isprint((int)wParam) && (lParam & (1 << 30)) == 0)
Engine::_ENGINE->OnASCIIDown((char)wParam);
return 0;
case WM_CLOSE:
Engine::_ENGINE->_exit = true;
return 0;
}
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
// Custom function for getting our exe name
WCHAR* Engine::_GetModuleName() {
static WCHAR* TITLE = NULL;
static WCHAR BUFFER[MAX_PATH];
if (TITLE != NULL)
return TITLE;
// Remove the path
GetModuleFileName(NULL, BUFFER, MAX_PATH);
TITLE = wcsrchr(BUFFER, '');
if (TITLE == NULL) {
wcscpy(BUFFER, L"Application");
TITLE = BUFFER;
return TITLE;
}
TITLE++;
// Remove the extension
WCHAR* ext = wcsrchr(BUFFER, '.');
if (ext)
*ext = 0;
return TITLE;
}
// Startup DirectX here
bool Engine::_DirectXStartup() {
// Startup Direct X
_directx = Direct3DCreate9(D3D_SDK_VERSION);
if (_directx == NULL)
return false;
// Create a Direct X device
D3DPRESENT_PARAMETERS d3dpp;
ZeroMemory(&d3dpp, sizeof(d3dpp));
d3dpp.Windowed = TRUE;
d3dpp.hDeviceWindow = _window;
d3dpp.BackBufferWidth = _WIDTH;
d3dpp.BackBufferHeight = _HEIGHT;
d3dpp.BackBufferCount = 1;
d3dpp.BackBufferFormat = D3DFMT_A8R8G8B8;
d3dpp.EnableAutoDepthStencil = TRUE;
d3dpp.AutoDepthStencilFormat = D3DFMT_D24X8;
d3dpp.SwapEffect = D3DSWAPEFFECT_COPY;
HRESULT result = _directx->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, _window, D3DCREATE_HARDWARE_VERTEXPROCESSING, &d3dpp, &_device);
if (FAILED(result))
result = _directx->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_REF, _window, D3DCREATE_SOFTWARE_VERTEXPROCESSING, &d3dpp, &_device);
if (FAILED(result))
return false;
return true;
}
// Shutdown DirectX here
bool Engine::_DirectXShutdown() {
if (_device) {
_device->Release();
_device = NULL;
}
if (_directx) {
_directx->Release();
_directx = NULL;
}
return true;
}
发动机.h
#ifndef _ENGINE_H_
#define _ENGINE_H_
#define _CRT_SECURE_NO_WARNINGS
#include <Windows.h>
#include <windowsx.h>
#include <stdio.h>
#include <d3d9.h>
#include <d3dx9.h>
class Engine {
public:
// Return the current singleton of this Engine class
static Engine* GetInstance();
// Constructor and deconstructor
Engine();
virtual ~Engine();
// Run the Engine class
bool Run();
// Return useful information about the class
LPDIRECT3DDEVICE9 GetDevice();
int GetWidth();
int GetHeight();
// Use for debug output
static void Debug(const char* message, ...);
// Virtual callbacks
virtual void OnStartup() {}
virtual void OnShutdown() {}
virtual void OnMouseDown(int x, int y) {}
virtual void OnKeyDown(int key) {}
virtual void OnASCIIDown(char key) {}
virtual void OnDraw() {}
private:
static Engine* _ENGINE;
static const int _WIDTH = 854;
static const int _HEIGHT = 480;
static const int _FPS = 60;
bool _exit;
HWND _window;
LPDIRECT3D9 _directx;
LPDIRECT3DDEVICE9 _device;
static LRESULT CALLBACK _WND_PROC(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
WCHAR* _GetModuleName();
bool _DirectXStartup();
bool _DirectXShutdown();
};
#endif // _ENGINE_H_
三角形2D.h
#ifndef _TRIANGLE_2D_H_
#define _TRIANGLE_2D_H_
#include "Engine.h"
class Triangle2D {
public:
Triangle2D();
bool New(FLOAT x, FLOAT y, FLOAT width, FLOAT height, DWORD color);
void Delete();
void Draw();
void Draw(FLOAT x, FLOAT y, FLOAT width, FLOAT height, DWORD color);
private:
struct CustomVertex {
FLOAT x, y, z, w;
DWORD color;
};
static const DWORD _FVF = D3DFVF_XYZRHW | D3DFVF_DIFFUSE;
LPDIRECT3DVERTEXBUFFER9 _vb;
};
#endif // _BOX_2D_H_
三角形2D.cpp
#include "Triangle2D.h"
Triangle2D::Triangle2D()
: _vb(NULL)
{
}
bool Triangle2D::New(FLOAT x, FLOAT y, FLOAT width, FLOAT height, DWORD color) {
if (FAILED(Engine::GetInstance()->GetDevice()->CreateVertexBuffer(sizeof(CustomVertex)* 4, D3DUSAGE_WRITEONLY, _FVF, D3DPOOL_DEFAULT, &_vb, NULL)))
return false;
CustomVertex* vertices;
_vb->Lock(0, 0, (void**)&vertices, 0);
vertices[0].x = x;
vertices[0].y = y;
vertices[0].z = 0.0f;
vertices[0].w = 1.0f;
vertices[0].color = color;
vertices[1].x = x + width;
vertices[1].y = y;
vertices[1].z = 0.0f;
vertices[1].w = 1.0f;
vertices[1].color = color;
vertices[2].x = x;
vertices[2].y = y + height;
vertices[2].z = 0.0f;
vertices[2].w = 1.0f;
vertices[2].color = color;
_vb->Unlock();
return true;
}
void Triangle2D::Delete(){
if (_vb) {
_vb->Release();
_vb = NULL;
}
}
void Triangle2D::Draw() {
Engine::GetInstance()->GetDevice()->BeginScene();
Engine::GetInstance()->GetDevice()->SetFVF(_FVF);
Engine::GetInstance()->GetDevice()->SetStreamSource(0, _vb, 0, sizeof(CustomVertex));
Engine::GetInstance()->GetDevice()->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2);
Engine::GetInstance()->GetDevice()->EndScene();
}
void Triangle2D::Draw(FLOAT x, FLOAT y, FLOAT width, FLOAT height, DWORD color) {
CustomVertex* vertices;
_vb->Lock(0, 0, (void**)&vertices, 0);
vertices[0].x = x;
vertices[0].y = y;
vertices[0].z = 0.0f;
vertices[0].w = 1.0f;
vertices[0].color = color;
vertices[1].x = x + width;
vertices[1].y = y;
vertices[1].z = 0.0f;
vertices[1].w = 1.0f;
vertices[1].color = color;
vertices[2].x = x;
vertices[2].y = y + height;
vertices[2].z = 0.0f;
vertices[2].w = 1.0f;
vertices[2].color = color;
_vb->Unlock();
Draw();
}
Direct3D 不绘制"圆圈"。它本身只绘制三个基本基元：点、线和三角形。对于它如何绘制这些东西，有很多选项，但这就是它可以原生绘制的全部内容。OpenGL也是如此（它有时也可以画"四边形"，但你总是可以画一个带有两个三角形的四边形）。
通常，绘制圆圈和其他平滑对象最好通过"矢量图形"库来完成。这些可以在正确的分辨率下渲染光滑对象（如圆）的高质量近似值。这是旧版 GDI 库的功能，也是 Direct2D 可以执行的操作。你可以为圆编写自己的近似值，但效果可能不如 Direct2D。这些库最终会为 Direct3D 执行的实际绘图操作生成点、线和三角形。
因此，如果你正在执行"演示"图形，则应考虑使用 Direct2D 而不是 Direct3D。大多数游戏实际上从未画过真正的圆圈。他们使用 Direct3D 将 2D 精灵绘制为两个带纹理的三角形，使用艺术家在 Photoshop 或 Paint 等东西中绘制的圆圈图像。
如果你坚持使用 Direct3D，请参阅 Direct3D 11 DebugDraw 帮助程序的 DirectX 工具包，该工具包可以绘制"环"（即 3D 空间中的线段圆）。这应该让您了解如何完成此操作。此代码始终使用 32 个段来形成环，但"矢量图形"库将根据它将在屏幕上覆盖的像素数来确定将其分解为多少个段：
void XM_CALLCONV DX::DrawRing(PrimitiveBatch<VertexPositionColor>* batch,
FXMVECTOR origin,
FXMVECTOR majorAxis,
FXMVECTOR minorAxis,
GXMVECTOR color)
{
static const size_t c_ringSegments = 32;
VertexPositionColor verts[c_ringSegments + 1];
FLOAT fAngleDelta = XM_2PI / float(c_ringSegments);
// Instead of calling cos/sin for each segment we calculate
// the sign of the angle delta and then incrementally calculate sin
// and cosine from then on.
XMVECTOR cosDelta = XMVectorReplicate(cosf(fAngleDelta));
XMVECTOR sinDelta = XMVectorReplicate(sinf(fAngleDelta));
XMVECTOR incrementalSin = XMVectorZero();
static const XMVECTORF32 s_initialCos =
{
1.f, 1.f, 1.f, 1.f
};
XMVECTOR incrementalCos = s_initialCos.v;
for (size_t i = 0; i < c_ringSegments; i++)
{
XMVECTOR pos = XMVectorMultiplyAdd(majorAxis, incrementalCos, origin);
pos = XMVectorMultiplyAdd(minorAxis, incrementalSin, pos);
XMStoreFloat3(&verts[i].position, pos);
XMStoreFloat4(&verts[i].color, color);
// Standard formula to rotate a vector.
XMVECTOR newCos = incrementalCos * cosDelta - incrementalSin * sinDelta;
XMVECTOR newSin = incrementalCos * sinDelta + incrementalSin * cosDelta;
incrementalCos = newCos;
incrementalSin = newSin;
}
verts[c_ringSegments] = verts[0];
batch->Draw(D3D11_PRIMITIVE_TOPOLOGY_LINESTRIP, verts, c_ringSegments + 1);
}
Direct3D9是旧版的，除非你专门针对Windows XP，否则如果你真的在做2D演示图形，你应该使用Direct3D 11或Direct2D。
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