/* A 2D Bezier surface, with 2x3 control points. 

Written by Scott D. Anderson
scott.anderson@acm.org
Fall 2007

*/

#include <stdio.h>
#include <stdlib.h>             // for atoi and exit
#include <tw.h>
#include "bezier-utils.h"

const int U_Order = 3;
const int V_Order = 2;
bool Wirep = true;
bool ShowControlPointsp = true;

/* ================================================================================
   A control-point arrays for a Bezier patches.  This is flat (all Z
   components are zero), and symmetrical across both X and Y.  The corners
   form an 8x4 rectangle.  

*/

GLfloat control_points[U_Order*V_Order*3] = {
    -4, +2, 0,
    0, 0, 0,
    +4, +2, 0,

    -4, -2, 0,
    0, 0, 0,
    +4, -2, 0  
};

void display(void) {
    twError();
    twDisplayInit();
    twCamera();

    glPushAttrib(GL_ALL_ATTRIB_BITS);

    glColor3f(0,1,0);           // green patch

    if(ShowControlPointsp)
        drawBezierSurfaceControlPoints(U_Order,3,V_Order,3*U_Order,control_points);
    
    drawBezierSurface(Wirep?GL_LINE:GL_FILL,
                      U_Order,16,V_Order,16,control_points);

    twError();

    glPopAttrib();
    glFlush();
    glutSwapBuffers();
}

void toggles(unsigned char key, int x, int y) {
    switch(key) {
    case 'w': Wirep = !Wirep; break;
    case 'c': ShowControlPointsp = !ShowControlPointsp; break;
    }
    glutPostRedisplay();
}

int main(int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    twInitWindowSize(500,500);
    glutCreateWindow(argv[0]);
    twError();
    glutDisplayFunc(display);
    twError();
    twBoundingBox(-4,+4,
                  -2,+2,
                  -1,1);
    twMainInit();            
    twKeyCallback('w',toggles,"toggle wireframe");
    twKeyCallback('c',toggles,"toggle showing control points");
    printBezierSurfaceControlPoints(U_Order,3,V_Order,3*U_Order,control_points);
    glutMainLoop();
    return 0;
}