コード:

Microsoft(R) Program Maintenance Utility Version 14.11.25508.2
Copyright (C) Microsoft Corporation.  All rights reserved.

        cl /c /TP /EHsc /I"d:\GL" /W3 c1.cpp
Microsoft(R) C/C++ Optimizing Compiler Version 19.11.25508.2 for x86
Copyright (C) Microsoft Corporation.  All rights reserved.

c1.cpp
        link /out:c1.exe /LIBPATH:"d:\GL" c1.obj
Microsoft (R) Incremental Linker Version 14.11.25508.2
Copyright (C) Microsoft Corporation.  All rights reserved.

        c1.exe
6.7082
5.97858
5.6045
5.30282
5.03388
4.875
4.89435
5.07168
5.31897
5.5863
6
6.7082
5.97858
5.6045
5.30282
5.03388
4.875
4.89435
5.07168
5.31897
5.5863
6

D:\z17c\GL\001\maingl>

コード:

#include<iostream>        //C言語標準ライブラリのインクルード
#include<GL/glut.h>       //GLUTヘッダファイルのインクルード
#include<GL/gl.h>         //GLヘッダファイルのインクルード
#include<math.h>


double clt[4][3] =
{
    { 1,2,0 },
    { 2,3,0 },
    { 3,1,0 },
    { 5,1,0 },
};

//プロトタイプ宣言

void init(void);
void keyboard(unsigned char key, int x, int y);
void display(void);
void resize(int w, int h);


int main(int argc, char **argv)
{
    glutInit(&argc, argv);
    /* ウィンドウの生成 */
    glutInitDisplayMode(GLUT_RGBA | GLUT_SINGLE | GLUT_DEPTH);
    glutInitWindowPosition(200, 50);
    glutInitWindowSize(400, 400);
    glutCreateWindow(argv[0]);
    init();
    glutReshapeFunc(resize);
    glutDisplayFunc(display);
    glutKeyboardFunc(keyboard);
    glutMainLoop();

    return 0;
}

void keyboard(unsigned char key, int x, int y)
{
    switch (key) {
    case '\33':
    case 'q':
    case 'Q':
        exit(0);
        break;
    default:
        break;
    }
}


void display(void)
{

    float x, y, x1, y1, x2, y2, t, s;

    float length = 0;

    for (s = 0.0; s<1.1; s += 0.1)
    {

        glLineWidth(1.0f);
        glBegin(GL_LINE_STRIP);
        glColor3f(0.0, 1.0, 0.0);

        x = pow((1 - s), 3) * clt[0][0] + 3 * pow((1 - s), 2)*s * clt[1][0] + 3 * (1 - s)*pow(s, 2) * clt[2][0] + pow(s, 3) * clt[3][0];
        y = pow((1 - s), 3) * clt[0][1] + 3 * pow((1 - s), 2)*s * clt[1][1] + 3 * (1 - s)*pow(s, 2) * clt[2][1] + pow(s, 3) * clt[3][1];

        x1 = -3 * pow((1 - s) ,2) * clt[0][0]+  3 * s * (1 - s) * (1 - 3 * s) * clt[1][0] + 3 * s * (2 - 3 * s) * clt[2][0] + 3 * pow(s,2)*   clt[3][0];
        y1 =  3 * pow((1 - s), 2) * clt[0][1] + 3 * s * (1 - s) * (1 - 3 * s) * clt[1][1] + 3 * s * (2 - 3 * s) * clt[2][1] + 3 * pow(s, 2) * clt[3][1];

        length = sqrt(x1*x1 + y1*y1);

        std::cout << length << std::endl;


        for (x2 = x; x2 <= x + x1; x2 += 0.01)
        {
            if (x1 == 0)
            {
                glVertex2f(x, y);
                glVertex2f(x, y1);
            }
            else
            {
                y2 = (y1 / x1)*(x2 - x) + y;
                glVertex2f(x2, y2);
            }
        }
        glEnd();
    }


    glColor3f(1.0, 0.0, 0.0);

    glBegin(GL_LINE_STRIP);

    for (t = 0; t<1.1; t += 0.1)
    {

        x = pow((1 - t), 3) * clt[0][0] + 3 * pow((1 - t), 2)*t * clt[1][0] + 3 * (1 - t)*pow(t, 2) * clt[2][0] + pow(t, 3) * clt[3][0];
        y = pow((1 - t), 3) * clt[0][1] + 3 * pow((1 - t), 2)*t * clt[1][1] + 3 * (1 - t)*pow(t, 2) * clt[2][1] + pow(t, 3) * clt[3][1];

        glVertex2f(x, y);
    };

    glEnd();

    glFlush();

}


void resize(int w, int h)
{


    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    if (w <= h)
        glOrtho(-5.0, 20.0, -5.0*(GLfloat)h / (GLfloat)w,
            12.5*(GLfloat)h / (GLfloat)w, -10.0, 5.0);
    else
        glOrtho(-5.0*(GLfloat)w / (GLfloat)h,
            5.0*(GLfloat)w / (GLfloat)h, -5.0, 5.0, -5.0, 5.0);
    glScalef(3, 3, 3);
}


void init(void)
{
    glClearColor(0.0, 0.0, 0.0, 0.0);
}