OpenGL 绘制自定义的弧形绘制自定义的圆绘制饼图

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本文介绍了一个使用OpenGL绘制自定义弧形、圆形及饼图的具体实现方法。通过三角扇和三角带两种基本图形来构建复杂的图形元素，实现了不同角度的弧线绘制，并展示了如何通过调整参数来绘制完整的圆形和特定角度范围内的饼图。

OpenGL 绘制自定义的弧形绘制自定义的圆绘制饼图

//rorger,2011 //contact me: jhcyd112@163.com #include "windows.h" #include "glut.h" #include "math.h" #define width 640 #define height 480 void drawArc(double x,double y,double start_angle,double end_angle,double delta_angle,double radius) { glBegin(GL_TRIANGLE_FAN); for (double i=start_angle;i<=end_angle;i+=delta_angle) { double vx=x+radius * cos(i); double vy=y+radius*sin(i); glVertex2d(vx,vy); } glEnd(); } void drawCircle(double x, double y, double radius) { double pi=acos(-1.0); drawArc(x,y,0,2*pi,pi/180,radius); } void drawPie(double x,double y,double start_angle,double end_angle,double delta_angle,double radius) { drawArc(x,y,start_angle,end_angle,delta_angle,radius); glBegin(GL_TRIANGLE_STRIP); glVertex2d(x,y); glVertex2d(x+radius*cos(start_angle),y+radius*sin(start_angle)); glVertex2d(x+radius*cos(end_angle),y+radius*sin(end_angle)); glEnd(); } void myDisplay(void) // plot the sinc function, using world coordinates { double pi=acos(-1.0); glClear(GL_COLOR_BUFFER_BIT); //画笛卡尔坐标系 glColor3f(1.0,0.0,0.0); glBegin(GL_LINES); glVertex2d(-width/2.0,0); glVertex2d(width/2.0,0); glEnd(); glBegin(GL_LINES); glVertex2d(0,height/2.0); glVertex2d(0,-height/2.0); glEnd(); glColor3f(1.0,1.0,0.0); //draw a circle drawCircle(0,0,100); //draw four arcs drawArc(0,0,0,pi/2.0,pi/180,200); drawArc(0,0,pi/2.0,pi,pi/180,200); drawArc(0,0,pi,3*pi/2.0,pi/180,200); drawArc(0,0,3*pi/2.0,2*pi,pi/180,200); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glColor4f(0.1,1.0f,0.0,0.5); //draw two pies drawPie(0,0,5*pi/4.0,7*pi/4.0,pi/180.0,200); drawPie(0,0,pi/4.0,3*pi/4.0,pi/180.0,200); glDisable(GL_BLEND); glFlush(); } void myInit(void) { glClearColor(0.0, 0.0, 0.0, 0.0); glColor3f(0.0f, 0.0f, 1.0f); glPointSize(4.0); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluOrtho2D(-width/2.0,width/2.0,-height/2.0,height/2.0); glLineWidth(2.0); } void main(int argc, char** argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_SINGLE |GLUT_RGBA); glutInitWindowSize(width,height); glutInitWindowPosition(100,150); glutCreateWindow("LineInterSectoin"); glutDisplayFunc(myDisplay); myInit( ); glutMainLoop( ); }