 [【技术文档】][转]直线生成算法之DDA | |
[图形学]直线生成算法之DDA DDA称为数值微分画线算法，是直线生成算法中最简单的一种。原理相当简单，就是最直观的根据斜率的偏移程度，决定是以x为步进方向还是以y为步进方向。然后在相应的步进方向上，步进变量每次增加一个像素，而另一个相关坐标变量则为Yk_1=Yk+m（以x为步进变量为例，m为斜率） 这个程序对于我的意义在于：可以在VC中利用GDI的画点函数--- SetPixel来实现它，终于可以告别C语言绘图还用TC的时代，呵呵~~~ void DDALine(float x1,float y1,float x2,float y2,int color,HDC hdc) { float m; float dx,dy; float x,y; x1=(int)(x1+0.5); y1=(int)(y1+0.5); x=x1; y=y1; dx=x2-x1; dy=y2-y1; if(fabs(dx)>=fabs(dy)) m=dy/dx; else m=dx/dy; while(x<=x2) { SetPixel(hdc,x,y,color); if(fabs(dx)>=dy) { y=y+m; x++; } else { x=x+m; y++; } } } VC中的实现: #include "GraphAlgorithm.h" #include<windows.h> #include <stdlib.h> #include <string.h> #include <stdio.h> long WINAPI WndProc(HWND hWnd,UINT iMessage,WPARAM wParam,LPARAM lParam); BOOL InitWindowsClass(HINSTANCE hInstance); BOOL InitWindows(HINSTANCE hInstance,int nCmdShow); HWND hWndMain; LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM); //program starting. int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInst,LPSTR lpszCmdLine,int nCmdShow) { MSG msg; if(!InitWindowsClass(hInstance)) return FALSE; if(!InitWindows(hInstance,nCmdShow)) return FALSE; //Core message looping while(GetMessage(&msg,NULL,0,0)) { TranslateMessage(&msg); DispatchMessage(&msg); } return msg.wParam; } //main wndProc function: message looping long WINAPI WndProc(HWND hWnd,UINT iMessage,WPARAM wParam,LPARAM lParam) { HDC hDC; HBRUSH hBrush; HPEN hPen; PAINTSTRUCT PtStr; switch(iMessage) { case WM_PAINT: //First draw,a black line hDC=BeginPaint(hWnd,&PtStr); hPen=(HPEN)GetStockObject(NULL_PEN);//get empty brush SelectObject(hDC,hPen); hBrush=(HBRUSH)GetStockObject(BLACK_BRUSH); SelectObject(hDC,hBrush); hPen=CreatePen(PS_SOLID,2,RGB(255,0,0));//create pen SelectObject(hDC,hPen); DDALine(0,0,200,200,1,hDC); DeleteObject(hPen); DeleteObject(hBrush); EndPaint(hWnd,&PtStr); return 0; case WM_DESTROY: PostQuitMessage(0); return 0; default: return DefWindowProc(hWnd,iMessage,wParam,lParam); } } //Init the Window to show out. BOOL InitWindows(HINSTANCE hInstance,int nCmdShow) { HWND hWnd; hWnd=CreateWindow("WinFill", "图形绘制算法示例程序", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL ); if(!hWnd) return FALSE; hWndMain=hWnd; ShowWindow(hWnd,nCmdShow); UpdateWindow(hWnd); return TRUE; } //Set wndClass Propertity BOOL InitWindowsClass(HINSTANCE hInstance) { WNDCLASS wndClass; wndClass.cbClsExtra=0; wndClass.cbWndExtra=0; wndClass.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH); wndClass.hCursor=LoadCursor(NULL,IDC_ARROW); wndClass.hIcon=LoadIcon(NULL,"END"); wndClass.hInstance=hInstance; wndClass.lpfnWndProc=WndProc; wndClass.lpszClassName="WinFill"; wndClass.lpszMenuName=NULL; wndClass.style=CS_HREDRAW|CS_VREDRAW; return RegisterClass(&wndClass); } 通过测试表明,当斜率较大时,如3以上,出现了些小锯齿. 继续前进!!! Trackback: http://tb.blog.csdn.net/TrackBack.aspx?PostId=531093 | |
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VC中好像没有“GraphAlgorithm.h”头文件 | |
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