用OpenGL画Bezier曲线

    最近在看Francis S Hill ,Jr 和 Stephen M Kelley合著的《计算机图形学》(OpenGL版)(第三版)书中有绘制三个控制点的Bezier曲线的代码。自己重新敲了一遍代码。发现了其中的一点小错误，修正过来了。并做了一点小小的改动。

源码见下

#include <windows.h> #include <math.h> #include <gl/GL.h> #include <gl/glut.h> 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[3]; 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(); } //三个控制点的贝塞尔曲线 Point drawBezier(Point A, Point B, Point C, double t) { Point P; P.x = pow((1-t), 2) * A.x + 2*t*(1-t)*B.x + pow(t, 2)*C.x; P.y = pow((1-t), 2) * A.y + 2*t*(1-t)*B.y + pow(t, 2)*C.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 == 3) { glColor3f(1.0, 0.0, 1.0); drawDot(abc[0]); drawDot(abc[1]); drawDot(abc[2]); glColor3f(1.0, 1.0, 0.0); drawLine(abc[0], abc[1]); drawLine(abc[1], abc[2]); 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], 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; }