OpenGLUT 0.6.3 development - OpenGLUT: trim.c File Reference
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# trim.c File Reference

## Detailed Description

This program draws a NURBS surface in the shape of a symmetrical hill, using both a NURBS curve and pwl (piecewise linear) curve to trim part of the surface.

    /*
     * Copyright (c) 1993-1997, Silicon Graphics, Inc.
     * ALL RIGHTS RESERVED
     * Permission to use, copy, modify, and distribute this software for
     * any purpose and without fee is hereby granted, provided that the above
     * copyright notice appear in all copies and that both the copyright notice
     * and this permission notice appear in supporting documentation, and that
     * the name of Silicon Graphics, Inc. not be used in advertising
     * or publicity pertaining to distribution of the software without specific,
     * written prior permission.
     *
     * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
     * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
     * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
     * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
     * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
     * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
     * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
     * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
     * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
     * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
     * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
     * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
     *
     * US Government Users Restricted Rights
     * Use, duplication, or disclosure by the Government is subject to
     * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
     * (c)(1)(ii) of the Rights in Technical Data and Computer Software
     * clause at DFARS 252.227-7013 and/or in similar or successor
     * clauses in the FAR or the DOD or NASA FAR Supplement.
     * Unpublished-- rights reserved under the copyright laws of the
     * United States.  Contractor/manufacturer is Silicon Graphics,
     * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
     *
     * OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
     */

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

    #ifndef CALLBACK
    #define CALLBACK
    #endif

    GLfloat ctlpoints[4][4][3];

    GLUnurbsObj *theNurb;

    /*
     *  Initializes the control points of the surface to a small hill.
     *  The control points range from -3 to +3 in x, y, and z
     */
    void init_surface(void)
    {
       int u, v;
       for (u = 0; u < 4; u++) {
          for (v = 0; v < 4; v++) {
             ctlpoints[u][v][0] = 2.0*((GLfloat)u - 1.5);
             ctlpoints[u][v][1] = 2.0*((GLfloat)v - 1.5);

             if ( (u == 1 || u == 2) && (v == 1 || v == 2))
                ctlpoints[u][v][2] = 3.0;
             else
                ctlpoints[u][v][2] = -3.0;
          }
       }
    }

    void nurbsError(GLenum errorCode)
    {
       const GLubyte *estring;

       estring = gluErrorString(errorCode);
       fprintf (stderr, "Nurbs Error: %s\n", (char *) estring);
       exit (0);
    }

    /*  Initialize material property and depth buffer.
     */
    void init(void)
    {
       GLfloat mat_diffuse[] = { 0.7, 0.7, 0.7, 1.0 };
       GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 1.0 };
       GLfloat mat_shininess[] = { 100.0 };

       glClearColor (0.0, 0.0, 0.0, 0.0);
       glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);
       glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
       glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);

       glEnable(GL_LIGHTING);
       glEnable(GL_LIGHT0);
       glEnable(GL_DEPTH_TEST);
       glEnable(GL_AUTO_NORMAL);
       glEnable(GL_NORMALIZE);

       init_surface();

       theNurb = gluNewNurbsRenderer();
       gluNurbsProperty(theNurb, GLU_SAMPLING_TOLERANCE, 25.0);
       gluNurbsProperty(theNurb, GLU_DISPLAY_MODE, GLU_FILL);
       gluNurbsCallback(theNurb, GLU_ERROR,
                        (GLvoid (CALLBACK*) ()) nurbsError);
    }

    void display(void)
    {
       GLfloat knots[8] = {0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0};
       GLfloat edgePt[5][2] = /* counter clockwise */
          {{0.0, 0.0}, {1.0, 0.0}, {1.0, 1.0}, {0.0, 1.0}, {0.0, 0.0}};
       GLfloat curvePt[4][2] = /* clockwise */
          {{0.25, 0.5}, {0.25, 0.75}, {0.75, 0.75}, {0.75, 0.5}};
       GLfloat curveKnots[8] =
          {0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0};
       GLfloat pwlPt[4][2] = /* clockwise */
          {{0.75, 0.5}, {0.5, 0.25}, {0.25, 0.5}};

       glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
       glPushMatrix();
       glRotatef(330.0, 1.,0.,0.);
       glScalef (0.5, 0.5, 0.5);

       gluBeginSurface(theNurb);
       gluNurbsSurface(theNurb, 8, knots, 8, knots,
                       4 * 3, 3, &ctlpoints[0][0][0],
                       4, 4, GL_MAP2_VERTEX_3);
       gluBeginTrim (theNurb);
          gluPwlCurve (theNurb, 5, &edgePt[0][0], 2, GLU_MAP1_TRIM_2);
       gluEndTrim (theNurb);
       gluBeginTrim (theNurb);
          gluNurbsCurve (theNurb, 8, curveKnots, 2,
                         &curvePt[0][0], 4, GLU_MAP1_TRIM_2);
          gluPwlCurve (theNurb, 3, &pwlPt[0][0], 2, GLU_MAP1_TRIM_2);
       gluEndTrim (theNurb);
       gluEndSurface(theNurb);

       glPopMatrix();
       glFlush();
    }

    void reshape(int w, int h)
    {
       glViewport(0, 0, (GLsizei) w, (GLsizei) h);
       glMatrixMode(GL_PROJECTION);
       glLoadIdentity();
       gluPerspective (45.0, (GLdouble)w/(GLdouble)h, 3.0, 8.0);

       glMatrixMode(GL_MODELVIEW);
       glLoadIdentity();
       glTranslatef (0.0, 0.0, -5.0);
    }

    /* ARGSUSED1 */
    void keyboard(unsigned char key, int x, int y)
    {
       switch (key) {
          case 27:
             exit(0);
             break;
       }
    }

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

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