OpenGL通過中點法繪製直線和圓
阿新 • • 發佈:2020-02-20
本文例項為大家分享了OpenGL繪製直線和圓的具體程式碼,供大家參考,具體內容如下
#include <gl/glut.h> #include <math.h> static int i=1; void Initial(void) { glClearColor(1.0f,1.0f,1.0f); //設定視窗背景顏色為白色 glMatrixMode(GL_PROJECTION); //指定設定投影引數 gluOrtho2D(-200.0,200.0,-200.0,200.0); //設定投影引數 //指的是檢視範圍,如果(0,200,200)的話就只能在第一象限顯示,就1/4圓,第1,3的引數是左下角座標,第2,4的引數是右上角座標 } /*void Display(void) { glClear(GL_COLOR_BUFFER_BIT); //用當前背景色填充視窗 glColor3f(1.0f,0.0f,0.0f); //設定當前的繪圖顏色為紅色 glRectf(50.0f,100.0f,150.0f,50.0f); //繪製一個矩形 glFlush(); //處理所有的OpenGL程式 } */ void DDALine(int x0,int y0,int x1,int y1) { //glVertex2f(10,10); int dx,dy,epsl,k; float x,y,xIncre,yIncre; dx = x1 - x0; dy = y1 - y0; x = x0; y = y0; if(abs(dx)>abs(dy)) epsl=abs(dx); else epsl=abs(dy); xIncre=(float)dx/(float)epsl; yIncre=(float)dy/(float)epsl; glPointSize(2); glBegin(GL_POINTS); for(k = 0;k <= epsl; k++) { glColor3f(1.0f,0.0f); glVertex2f(int(x+0.5),int(y+0.5)); x += xIncre; y += yIncre; } glEnd(); } void Mid_B(int x0,int y1) { int dx,d,UpIncre,DownIncre,x,y; if(x0 > x1) { x = x1; x1 = x0; x0 = x; y = y1; y1 = y0; y0 = y; } x = x0; y = y0; dx = x1 - x0; dy = y1 - y0; d = dx - 2*dy; UpIncre = 2*dx - 2*dy; DownIncre =- 2*dy; glPointSize(2); glBegin(GL_POINTS); while(x <= x1) { glColor3f(1.0f,0.0f); glVertex2f(x,y); x++; if(d < 0) { y++; d += UpIncre; } else d += DownIncre; } glEnd(); } void G_B(int x0,int y1) { int x,dx,e; dx = x1 - x0; dy = y1 - y0; e =- dx; x=x0; y=y0; glPointSize(2); glBegin(GL_POINTS); while(x <= x1) { glColor3f(1.0f,y); x++; e = e + 2*dy; if(e > 0) { y++; e = e - 2*dx; } } glEnd(); } void CirclePoint(int x,int y) { glPointSize(2); glBegin(GL_POINTS); glColor3f(1.0f,y); glVertex2f(y,x); glVertex2f(-y,x); glVertex2f(-x,y); glVertex2f(-x,-y); glVertex2f(-y,-x); glVertex2f(y,-x); glVertex2f(x,-y); glEnd(); } void MidBresenhamCircle(int r) { int x = 0,y = r,d = 1-r; //glPointSize(2); //glBegin(GL_POINTS); while(x <= y) { CirclePoint(x,y); if(d < 0) d += 2*x+3; else { d += 2*(x-y)+5; y--; } x++; } glEnd(); } void ProcessMenu(int value) { i = value; glutPostRedisplay(); } void Display(void) { glClear(GL_COLOR_BUFFER_BIT); //用當前背景色填充視窗 glViewport(0,400,400); //前兩個引數改變原點座標,後兩個引數改變圖形長寬(放大縮小) switch(i) { case 1: DDALine(2,3,55,83); break; case 2: Mid_B(2,83); break; case 3: G_B(2,83); break; case 4: MidBresenhamCircle(50); break; } glFlush(); } int main(int argc,char* argv[]) { glutInit(&argc,argv); //初始化GLUT庫,處理命令列引數 glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); //初始化視窗的顯示模式 glutInitWindowSize(400,400); //設定視窗的尺寸 glutInitWindowPosition(100,100); //設定視窗的位置 glutCreateWindow("直線"); //建立一個名為矩形的視窗 int MainMenu = glutCreateMenu(ProcessMenu); //建立主選單 glutAddMenuEntry("DDA演算法",1); glutAddMenuEntry("中點Bresenham演算法",2); glutAddMenuEntry("改進的Bresenham演算法",3); glutAddMenuEntry("中點bresenham畫圓",4); glutAttachMenu(GLUT_RIGHT_BUTTON); glutDisplayFunc(Display); //設定當前視窗的顯示回撥函式 Initial(); //完成視窗初始化 glutMainLoop(); //啟動主GLUT事件處理迴圈 return 0; }
以上就是本文的全部內容,希望對大家的學習有所幫助,也希望大家多多支援我們。