opengl入门系列-Bezier曲线

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#include <stdio.h>
#include <GL/glut.h>
#include <stdlib.h>

GLfloat ctrlpoints[4][3] ={
   {-4.0, -4.0, 0.0},
   {-2.0, 4.0, 0.0},
    {2.0, -4.0, 0.0},
    {4.0, 4.0, 0.0}
};

void init(void)
{
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glShadeModel(GL_FLAT);
    glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 4, &ctrlpoints[0][0]);
    glEnable(GL_MAP1_VERTEX_3);
}

void display(void)
{
    int i;

    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1.0, 1.0, 1.0);
    glBegin(GL_LINE_STRIP);
    for(i = 0; i <= 100; i++)
        glEvalCoord1f((GLfloat)i/100.0);
    glEnd();

    glPointSize(5.0);
    glColor3f(1.0, 1.0, 0.0);
    glBegin(GL_POINTS);
    for(i = 0; i<4; i++)
        glVertex3fv(&ctrlpoints[i][0]);
    glEnd();

    glFlush();
}

void reshape(int w, int h)
{
    glViewport(0, 0, (GLsizei)w, (GLsizei)h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    if (w <= h)
       glOrtho(-5.0, 5.0, -5.0*(GLfloat)h/(GLfloat)w,
                5.0*(GLfloat)h/(GLfloat)w, -5.0, 5.0);
    else
       glOrtho(-5.0*(GLfloat)w/(GLfloat)h,
                5.0*(GLfloat)w/(GLfloat)h, -5.0, 5.0, -5.0, 5.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

void keyboard(unsigned char key, int x, int y)
{
   switch (key) {
      case 27:
         exit(0);
         break;
   }
}

int main(int argc, char** argv)
{
   glutInit(&argc, argv);
   glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
   glutInitWindowSize (500, 500);
   glutInitWindowPosition (100, 100);
   glutCreateWindow (argv[0]);
   init ();
   glutDisplayFunc(display);
   glutReshapeFunc(reshape);
   glutKeyboardFunc (keyboard);
   glutMainLoop();
   return 0;
}

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