使用De Casteljau算法在C ++，OpenGL中绘制贝塞尔曲线 [英] Drawing Bezier curves using De Casteljau Algorithm in C++ , OpenGL

问题描述

我试图找到的方式来生成贝塞尔曲线使用de casteljau算法我的任务之一在这里。我能够使用正常方法生成贝塞尔曲线，但无法开始使用上述算法生成。如果有人可以建议我正确的方向或分享你的任何代码片段将是很大的帮助。我不是只是问。我工作了很多，并写下面的代码自己生成的曲线。
我发现一个网络applet，确实需要我。 （http://www2.mat.dtu.dk/people/J.gravesen/cagd/decast.html）。建议我如何实现

I am trying to find the way to generate bezier curve using de casteljau algorithm for one of my assignment here. I am able to generate bezier curve using normal method but unable to start on generating using the above algorithm. It will be of great help if someone can suggest me to right direction or share any piece of code you have. I am not just asking as is. I worked a lot on it and wrote the following code myself to generate the curve. I found a web applet which does exactly i needed. (http://www2.mat.dtu.dk/people/J.Gravesen/cagd/decast.html). suggest me how to achieve that

#include <iostream>
using std::cerr;
using std::endl;
#include <stdlib.h>
//using std::exit;
#include <GL/glut.h> // GLUT stuff, includes OpenGL headers as well 
#include <windows.h>
#include <math.h>
#include <gl/Gl.h>
#include <gl/Glu.h>


int SCREEN_HEIGHT = 480;
// Keep track of times clicked, on 3 clicks draw.
int NUMPOINTS = 0;

// Point class to keep it a little cleaner.
class Point {
public:
    float x, y, z;
    void setxy(float x2, float y2) { x = x2; y = y2; }
    const Point & operator=(const Point &rPoint) {
         x = rPoint.x;
         y = rPoint.y;
         z = rPoint.z;

         return *this;
      }

};

Point abc[4];

void myInit() {
    glClearColor(0.0,0.0,0.0,0.0);
    glColor3f(1.0,0.0,0.0);
    glPointSize(4.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0.0,640.0,0.0,480.0);

}

void drawDot(int x, int y) {
    glBegin(GL_POINTS);
     glVertex2i(x,y);
    glEnd();
    glFlush();
}

void drawLine(Point p1, Point p2) {
    glBegin(GL_LINES);
      glVertex3f(p1.x, p1.y, p1.z);
      glVertex3f(p2.x, p2.y, p2.z);

    glEnd();
    glFlush();
}

// Calculate the next bezier point.
Point drawBezier(Point A, Point B, Point C, Point D, double t) {
    Point P;




    P.x = pow((1 - t), 3) * A.x + 3 * t * pow((1 -t), 2) * B.x + 3 * (1-t) * pow(t, 2)* C.x + pow (t, 3)* D.x;
    P.y = pow((1 - t), 3) * A.y + 3 * t * pow((1 -t), 2) * B.y + 3 * (1-t) * pow(t, 2)* C.y + pow (t, 3)* D.y;
    P.z = pow((1 - t), 3) * A.z + 3 * t * pow((1 -t), 2) * B.z + 3 * (1-t) * pow(t, 2)* C.z + pow (t, 3)* D.z;

    return P;
}

void myMouse(int button, int state, int x, int y) {
  // If left button was clicked
  if(button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) {
      // Store where the user clicked, note Y is backwards.
    abc[NUMPOINTS].setxy((float)x,(float)(SCREEN_HEIGHT - y));
    NUMPOINTS++;

    // Draw the red  dot.
    drawDot(x, SCREEN_HEIGHT - y);

    // If 3 points are drawn do the curve.
    if(NUMPOINTS == 4) {
        glColor3f(1.0,1.0,1.0);
        // Draw two legs of the triangle
        drawLine(abc[0], abc[1]);
        drawLine(abc[1], abc[2]);
        drawLine(abc[2], abc[3]);
        //drawLine(abc[3], abc[4]);
        Point POld = abc[0];
        /* Draw each segment of the curve.  Make t increment in
                   smaller amounts for a more detailed curve. */
        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 *argv[]) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
    glutInitWindowSize(640,480);
    glutInitWindowPosition(100,150);
    glutCreateWindow("Bezier Curve");

    glutMouseFunc(myMouse);
    glutDisplayFunc(myDisplay);

    myInit();
    glutMainLoop();

    return 0;
}

推荐答案

问题？

works for me, what is the problem?

我不会发布这个答案，但我不能在评论中发布图片

I wouldn't post this as an answer, but I can't post an image in a comment

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