凸包算法(Graham算法）实现，带图形
// 凸包.cpp : 定义应用程序的入口点。
//
#include "stdafx.h"
#include "凸包.h"
using namespace std;
#define MAX_LOADSTRING 100
#define MAXPOINTS 13
// 全局变量:
HINSTANCE hInst; // 当前实例
TCHAR szTitle[MAX_LOADSTRING]; // 标题栏文本
TCHAR szWindowClass[MAX_LOADSTRING]; // 主窗口类名
typedef vector<POINT> PTARRAY;
PTARRAY vecSrc;
// 此代码模块中包含的函数的前向声明:
ATOM MyRegisterClass(HINSTANCE hInstance);
BOOL InitInstance(HINSTANCE, int);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK About(HWND, UINT, WPARAM, LPARAM);
//判断两个点是否相等
bool operator==(const POINT &pt1,const POINT & pt2)
{
return (pt1.x==pt2.x &&pt1.y==pt2.y );
}
bool CompareVector(const POINT & pt1,const POINT & pt2)
{
float m1=sqrt((float)(pt1.x *pt1.x +pt1.y *pt1.y));
float m2=sqrt((float)(pt2.x *pt2.x +pt2.y *pt2.y));
//两个向量分别与(1,0)求内积
float v1=pt1.x /m1,v2=pt2.x /m2;
return (v1>v2||v1==v2&&m1<m2);
}
void CalConvexHULL(PTARRAY &vecSrc)
{
if(vecSrc.size ()<3)
{
return ;
}
//查找基点
POINT ptBase=vecSrc.front ();//将第一个点预设为最小的
for(PTARRAY::iterator i =vecSrc.begin ()+1;i!=vecSrc.end ();i++)
{
if(i->y <ptBase.y ||(i->y ==ptBase.y &&i->x <ptBase.x))
ptBase=*i;
}
//计算出各点与基点构成的向量
for(PTARRAY::iterator i=vecSrc.begin ();i!=vecSrc.end ();)
{
if(*i==ptBase)
{
i=vecSrc.erase (i);
}
else
{
i->x-=ptBase.x;
i->y-=ptBase.y;
i++;
}
}
sort(vecSrc.begin(),vecSrc.end (),&CompareVector);
vecSrc.erase (unique(vecSrc.begin (),vecSrc.end()),vecSrc.end ());
//计算得到首尾依次相连的向量
for(PTARRAY::reverse_iterator ri=vecSrc.rbegin ();ri!=vecSrc.rend ()-1;ri++)
{
PTARRAY::reverse_iterator riNext=ri+1;
ri->x -=riNext->x;
ri->y -=riNext->y;
}
for(PTARRAY::iterator i=vecSrc.begin ()+1;i!=vecSrc.end();i++)
{
for(PTARRAY::iterator iLast=i-1;iLast!=vecSrc.begin();)
{
//计算叉积
int v1=i->x *iLast->y;
int v2=i->y *iLast->x;
if(v1<v2||(v1==v2&&i->x*iLast->x >0&&i->y *iLast->y >0))
{
break;
}
i->x +=iLast->x;
i->y +=iLast->y;
iLast=(i=vecSrc.erase (iLast))-1;
}
}
vecSrc.front ().x+=ptBase.x;
vecSrc.front ().y+=ptBase.y;
for(PTARRAY::iterator i=vecSrc.begin ()+1;i!=vecSrc.end ();i++)
{
i->x +=(i-1)->x;
i->y+=(i-1)->y;
}
vecSrc.push_back (ptBase);
}
int APIENTRY _tWinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPTSTR lpCmdLine,
int nCmdShow)
{
UNREFERENCED_PARAMETER(hPrevInstance);
UNREFERENCED_PARAMETER(lpCmdLine);
// TODO: 在此放置代码。
MSG msg;
HACCEL hAccelTable;
// 初始化全局字符串
LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
LoadString(hInstance, IDC_MY, szWindowClass, MAX_LOADSTRING);
MyRegisterClass(hInstance);
// 执行应用程序初始化:
if (!InitInstance (hInstance, nCmdShow))
{
return FALSE;
}
hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_MY));
// 主消息循环:
while (GetMessage(&msg, NULL, 0, 0))
{
if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
return (int) msg.wParam;
}
//
// 函数: MyRegisterClass()
//
// 目的: 注册窗口类。
//
// 注释:
//
// 仅当希望
// 此代码与添加到 Windows 95 中的“RegisterClassEx”
// 函数之前的 Win32 系统兼容时，才需要此函数及其用法。调用此函数十分重要，
// 这样应用程序就可以获得关联的
// “格式正确的”小图标。
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
WNDCLASSEX wcex;
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;
wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_MY));
wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wcex.lpszMenuName = MAKEINTRESOURCE(IDC_MY);
wcex.lpszClassName = szWindowClass;
wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));
return RegisterClassEx(&wcex);
}
//
// 函数: InitInstance(HINSTANCE, int)
//
// 目的: 保存实例句柄并创建主窗口
//
// 注释:
//
// 在此函数中，我们在全局变量中保存实例句柄并
// 创建和显示主程序窗口。
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
HWND hWnd;
hInst = hInstance; // 将实例句柄存储在全局变量中
hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);
if (!hWnd)
{
return FALSE;
}
ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);
return TRUE;
}
//
// 函数: WndProc(HWND, UINT, WPARAM, LPARAM)
//
// 目的: 处理主窗口的消息。
//
// WM_COMMAND - 处理应用程序菜单
// WM_PAINT - 绘制主窗口
// WM_DESTROY - 发送退出消息并返回
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
int wmId, wmEvent;
PAINTSTRUCT ps;
HDC hdc;
HPEN pen,oldPen;
HBRUSH brush,oldBrush;
static int iCount=0;
switch (message)
{
case WM_LBUTTONDOWN:
if(iCount<MAXPOINTS)
{
POINT point;
point.x=LOWORD(lParam);
point.y=HIWORD(lParam);
vecSrc.push_back (point);
iCount++;
hdc=GetDC(hWnd);
brush=CreateSolidBrush(RGB(255,0,0));
oldBrush=(HBRUSH)SelectObject(hdc,brush);
Ellipse(hdc,LOWORD(lParam)-5,HIWORD(lParam)-5,LOWORD(lParam)+5,HIWORD(lParam)+5);
SelectObject(hdc,oldBrush);
DeleteObject(brush);
ReleaseDC(hWnd,hdc);
}
else
{
InvalidateRect(hWnd,NULL,false);
}
break;
case WM_COMMAND:
wmId = LOWORD(wParam);
wmEvent = HIWORD(wParam);
// 分析菜单选择:
switch (wmId)
{
case IDM_ABOUT:
DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
break;
case IDM_EXIT:
DestroyWindow(hWnd);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
break;
case WM_PAINT:
hdc = BeginPaint(hWnd, &ps);
// TODO: 在此添加任意绘图代码...
if(iCount>0)
{
CalConvexHULL(vecSrc);
pen=CreatePen(PS_SOLID,2,RGB(0,255,0));
oldPen=(HPEN)SelectObject(hdc,pen);
MoveToEx(hdc,vecSrc[0].x,vecSrc[0].y,NULL);
for(PTARRAY::iterator i=vecSrc.begin ()+1;i!=vecSrc.end();i++)
{
LineTo(hdc,i->x,i->y);
}
LineTo(hdc,vecSrc[0].x ,vecSrc[0].y);
SelectObject(hdc,oldPen);
}
EndPaint(hWnd, &ps);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
// “关于”框的消息处理程序。
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
UNREFERENCED_PARAMETER(lParam);
switch (message)
{
case WM_INITDIALOG:
return (INT_PTR)TRUE;
case WM_COMMAND:
if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
{
EndDialog(hDlg, LOWORD(wParam));
return (INT_PTR)TRUE;
}
break;
}
return (INT_PTR)FALSE;
}
输出结果为:
