学步园

    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><br /> #include <math.h><br /> #include <gl/GL.h><br /> #include <gl/glut.h><br /> int SCREEN_HEIGHT = 480;<br /> int NUMPOINTS = 0;<br /> class Point<br /> {<br /> public:<br /> float x, y;<br /> void setxy(float x2, float y2)<br /> {<br /> x = x2;<br /> y = y2;<br /> }<br /> Point operator&(const Point & rPoint)<br /> {<br /> x = rPoint.x;<br /> y = rPoint.y;<br /> return * this;<br /> }<br /> };<br /> Point abc[3];<br /> void myInit()<br /> {<br /> glClearColor(0.0,0.0,0.0,0.0);<br /> glColor3f(1.0f, 0.0, 0.0);<br /> glPointSize(4.0);<br /> glMatrixMode(GL_PROJECTION);<br /> glLoadIdentity();<br /> gluOrtho2D(0.0, 640, 0.0, 480.0);<br /> }<br /> void drawDot(Point pt)<br /> {<br /> glBegin(GL_POINTS);<br /> glVertex2f(pt.x, pt.y);<br /> glEnd();<br /> glFlush();<br /> }<br /> void drawLine(Point p1, Point p2)<br /> {<br /> glBegin(GL_LINES);<br /> glVertex2f(p1.x, p1.y);<br /> glVertex2f(p2.x, p2.y);<br /> glEnd();<br /> glFlush();<br /> }<br /> //三个控制点的贝塞尔曲线<br /> Point drawBezier(Point A, Point B, Point C, double t)<br /> {<br /> Point P;<br /> P.x = pow((1-t), 2) * A.x + 2*t*(1-t)*B.x + pow(t, 2)*C.x;<br /> P.y = pow((1-t), 2) * A.y + 2*t*(1-t)*B.y + pow(t, 2)*C.y;<br /> return P;<br /> }<br /> void myMouse(int button, int state, int x, int y)<br /> {<br /> if(button == GLUT_LEFT_BUTTON && state == GLUT_DOWN)<br /> {<br /> abc[NUMPOINTS].setxy((float)x, (float)(SCREEN_HEIGHT - y));<br /> NUMPOINTS++;<br /> if (NUMPOINTS == 3)<br /> {<br /> glColor3f(1.0, 0.0, 1.0);</p> <p> drawDot(abc[0]);<br /> drawDot(abc[1]);<br /> drawDot(abc[2]);<br /> glColor3f(1.0, 1.0, 0.0);<br /> drawLine(abc[0], abc[1]);<br /> drawLine(abc[1], abc[2]);<br /> glColor3f(0.0, 1.0, 1.0);<br /> Point POld = abc[0];<br /> for (double t = 0.0; t<=1.0;t+=0.1)<br /> {<br /> Point P = drawBezier(abc[0], abc[1], abc[2], t);<br /> drawLine(POld, P);<br /> POld = P;<br /> }<br /> glColor3f(1.0, 0.0, 0.0);<br /> NUMPOINTS = 0;<br /> }<br /> }<br /> }<br /> void myDisplay()<br /> {<br /> glClear(GL_COLOR_BUFFER_BIT);<br /> glFlush();<br /> }<br /> int main(int argc, char * agrv[])<br /> {<br /> glutInit(&argc, agrv);<br /> glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);<br /> glutInitWindowSize(640, 480);<br /> glutInitWindowPosition(100, 150);<br /> glutCreateWindow("Bezier Curve");<br /> glutMouseFunc(myMouse);<br /> glutDisplayFunc(myDisplay);<br /> myInit();<br /> glutMainLoop();<br /> return 0;<br /> }