BEZCURVE.C

/* 
 * (c) Copyright 1993, Silicon Graphics, Inc. 
 *               1993-1995 Microsoft Corporation 
 * 
 * ALL RIGHTS RESERVED 
 * 
 * Please refer to OpenGL/readme.txt for additional information 
 * 
 */ 
 
/*  bezcurve.c 
 *  This program uses evaluators to draw a Bezier 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); 
 
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 myinit(void) 
{ 
    glClearColor(0.0, 0.0, 0.0, 1.0); 
    glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 4, &ctrlpoints[0][0]); 
    glEnable(GL_MAP1_VERTEX_3); 
    glShadeModel(GL_FLAT); 
} 
 
void CALLBACK display(void) 
{ 
    int i; 
 
    glClear(GL_COLOR_BUFFER_BIT); 
    glColor3f(1.0, 1.0, 1.0); 
    glBegin(GL_LINE_STRIP); 
    for (i = 0; i <= 30; i++)  
        glEvalCoord1f((GLfloat) i/30.0); 
    glEnd(); 
    /* The following code displays the control points as dots. */ 
    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 CALLBACK myReshape(GLsizei w, GLsizei h) 
{ 
    if (!h) return; 
    glViewport(0, 0, w, 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(); 
} 
 
int main(int argc, char** argv) 
{ 
    auxInitDisplayMode (AUX_SINGLE | AUX_RGB); 
    auxInitPosition (0, 0, 500, 500); 
    auxInitWindow ("Bezier Curves Using Evaluators"); 
    myinit(); 
    auxReshapeFunc (myReshape); 
    auxMainLoop(display); 
    return(0); 
}