CURVE.C

/* 
 * (c) Copyright 1993, Silicon Graphics, Inc. 
 *               1993-1995 Microsoft Corporation 
 * 
 * ALL RIGHTS RESERVED 
 * 
 * Please refer to OpenGL/readme.txt for additional information 
 * 
 */ 
 
/* 
 *  curve.c 
 *  This program uses the Utility Library NURBS routines to 
 *  draw a one-dimensional NURBS curve. 
 */ 
#include "glos.h" 
 
#include <GL/gl.h> 
#include <GL/glu.h> 
#include <GL/glaux.h> 
 
void myinit(void); 
void CALLBACK myReshape(GLsizei w, GLsizei h); 
void CALLBACK display(void); 
 
GLUnurbsObj *theNurb; 
 
void myinit(void) 
{ 
    glShadeModel (GL_FLAT); 
    theNurb = gluNewNurbsRenderer(); 
    gluNurbsProperty (theNurb, GLU_SAMPLING_TOLERANCE, 10.0); 
} 
 
/*  This routine draws a B-spline curve.  Try a different  
 *  knot sequence for a Bezier curve.  For example, 
    GLfloat knots[8] = {0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0}; 
 */ 
 
void CALLBACK display(void) 
{ 
    GLfloat ctlpoints[4][3] = {{-.75, -.75, 0.0},  
    {-.5, .75, 0.0}, {.5, .75, 0.0}, {.75, -.75, 0.0}}; 
    GLfloat knots[8] = {0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0};  
 
    glClear(GL_COLOR_BUFFER_BIT); 
    glColor3f (1.0, 1.0, 1.0); 
    gluBeginCurve(theNurb); 
    gluNurbsCurve(theNurb,  
        8, knots, 
        3, 
        &ctlpoints[0][0],  
        4, 
        GL_MAP1_VERTEX_3); 
    gluEndCurve(theNurb); 
    glFlush(); 
} 
 
void CALLBACK myReshape(GLsizei w, GLsizei h) 
{ 
    if (!h) return; 
    glViewport(0, 0, w, h); 
    glMatrixMode(GL_PROJECTION); 
    glLoadIdentity(); 
    if (w <= h) 
    gluOrtho2D (-1.0, 1.0, -1.0 * (GLfloat) h/(GLfloat) w,  
        1.0 * (GLfloat) h/(GLfloat) w); 
    else 
    gluOrtho2D (-1.0 * (GLfloat) w/(GLfloat) h, 
        1.0 * (GLfloat) w/(GLfloat) h, -1.0, 1.0); 
    glMatrixMode(GL_MODELVIEW); 
    glLoadIdentity(); 
} 
 
/*  Main Loop  
 */ 
int main(int argc, char** argv) 
{ 
    auxInitDisplayMode (AUX_SINGLE | AUX_RGB); 
    auxInitPosition (0, 0, 500, 500); 
    auxInitWindow ("NURBS Curve"); 
    myinit(); 
    auxReshapeFunc (myReshape); 
    auxMainLoop(display); 
    return(0); 
}