使用OpenGL画三次Bezier曲线

#include   
#include   
#include   
#include   
int SCREEN_HEIGHT = 480;  
int NUMPOINTS = 0;  
class Point  
{  
public:  
	float x, y;  
	void setxy(float x2, float y2)  
	{  
		x = x2;  
		y = y2;  
	}  
	Point  operator&(const Point & rPoint)  
	{  
		x = rPoint.x;  
		y = rPoint.y;  
		return * this;  
	}  
};  
Point abc[4];  
void myInit()  
{  
	glClearColor(0.0,0.0,0.0,0.0);  
	glColor3f(1.0f, 0.0, 0.0);  
	glPointSize(4.0);  
	glMatrixMode(GL_PROJECTION);  
	glLoadIdentity();  
	gluOrtho2D(0.0, 640, 0.0, 480.0);  
}  
void drawDot(Point pt)   
{  
	glBegin(GL_POINTS);  
	glVertex2f(pt.x, pt.y);  
	glEnd();  
	glFlush();  
}  
void drawLine(Point p1, Point p2)  
{  
	glBegin(GL_LINES);  
	glVertex2f(p1.x, p1.y);  
	glVertex2f(p2.x, p2.y);  
	glEnd();  
	glFlush();  
}  
//四个控制点的贝塞尔曲线 即三次Bezier曲线
Point drawBezier(Point A, Point B, Point C, Point D,double t)   
{  
	Point P;
	double a1 = pow((1-t),3);
	double a2 = pow((1-t),2)*3*t;
	double a3 = 3*t*t*(1-t);
	double a4 = t*t*t;

	P.x = a1*A.x+a2*B.x+a3*C.x+a4*D.x;
	P.y = a1*A.y+a2*B.y+a3*C.y+a4*D.y;
	return P;  
}  
void myMouse(int button, int state, int x, int y)  
{  
	if(button == GLUT_LEFT_BUTTON && state == GLUT_DOWN)  
	{  
		abc[NUMPOINTS].setxy((float)x, (float)(SCREEN_HEIGHT - y));  
		NUMPOINTS++;  
		if (NUMPOINTS == 4)  
		{  
			glColor3f(1.0, 0.0, 1.0);  

			drawDot(abc[0]);  
			drawDot(abc[1]);  
			drawDot(abc[2]);  
			drawDot(abc[3]);  
			glColor3f(1.0, 1.0, 0.0);  
			drawLine(abc[0], abc[1]);  
			drawLine(abc[1], abc[2]);  
			drawLine(abc[2], abc[3]);  
			glColor3f(0.0, 1.0, 1.0);  
			Point POld = abc[0];  
			for (double t = 0.0; t<=1.0;t+=0.1)  
			{  
				Point P = drawBezier(abc[0], abc[1], abc[2],  abc[3], t);  
				drawLine(POld, P);  
				POld = P;  
			}  
			glColor3f(1.0, 0.0, 0.0);  
			NUMPOINTS = 0;  
		}  
	}  
}  
void myDisplay()  
{  
	glClear(GL_COLOR_BUFFER_BIT);  
	glFlush();  
}  
int main(int argc, char * agrv[])  
{  
	glutInit(&argc, agrv);  
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);  
	glutInitWindowSize(640, 480);  
	glutInitWindowPosition(100, 150);  
	glutCreateWindow("Bezier Curve");  
	glutMouseFunc(myMouse);  
	glutDisplayFunc(myDisplay);  
	myInit();  
	glutMainLoop();  
	return 0;  
} 

交互绘出Bezier曲线，见下图

参考书目

1.《实时计算机图形学》Tommas Akenine-Moller

2.《计算机图形学基础教程》 孔令德

3.《计算机图形学(OpenGl版)》Francis S Hill,Jr