/*
 * (c) Copyright 1993, Silicon Graphics, Inc.
 *               1993, 1994 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)
{
    h = (h == 0) ? 1 : h;
    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);
}
