/* A 2D Bezier surface, built as part of a class exercise.

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"

bool Wirep = true;
bool ShowControlPointsp = true;

void heartHalfCurve( GLfloat height ) {
    const int Order = 4;

    GLfloat h=height;           // shorthand

    GLfloat cp[Order*3] = {
        0,0,0,                  // first point of heart curve
        1,1,0,                  // second point of heart curve
        1,-h+1,0,               // third point of heart curve
        0,-h,0                  // fourth point of heart curve
    };
    if(ShowControlPointsp)
        drawBezierCurveControlPoints(Order,3,cp);
    
    drawBezierCurve(Order,3,16,cp);
 }


/* The width of the heart is 1 (at least, its control points) and the
height, from dent to point, is determined by the argument.  The origin is
at the dent, and the point is on the negative Y axis.  The heart comes out
(along Z) by 0.5.

*/

void heartHalfSurface( GLfloat height ) {
    // U varies fastest through the array, V slowest.
    // Our heart curve is along V.
    const int U_Order = 3;
    const int V_Order = 4;
    const GLfloat f=1/-3.0;           // move down by thirds

    GLfloat h=height;           // shorthand

    GLfloat cp[U_Order*V_Order*3] = {
        // they all come together at the dent
        0,0,0,
        0,0,0,
        0,0,0,                  // first point of heart curve

        0,h*f,0.5,
        0.5,h*f,0.5,
        1,1,0,                  // second point of heart curve

        0,2*h*f,0.5,
        0.5,2*h*f,0.5,
        1,-h+1,0,                // third point of heart curve

        0,-h,0,
        0,-h,0,
        0,-h,0                  // fourth point of heart curve
    };
    if(ShowControlPointsp)
        drawBezierSurfaceControlPoints(U_Order,3,V_Order,3*U_Order,cp);
    
    drawBezierSurface(Wirep?GL_LINE:GL_FILL, U_Order,16,V_Order,16,cp);
 }

/* Same as heart half, except we do both sides with one surface.  This
   gives us less control left-to-right, but is simpler. */

void heartWholeSurface( GLfloat height ) {
    // U varies fastest through the array, V slowest.
    // Our heart curve is along V.
    const int U_Order = 3;
    const int V_Order = 4;
    const GLfloat f=1/-3.0;           // move down by thirds

    GLfloat h=height;           // shorthand

    GLfloat cp[U_Order*V_Order*3] = {
        // they all come together at the dent
        0,0,0,
        0,0,0,
        0,0,0,                  // first point of heart curve

        -1,1,0,
        0,h*f,0.5,
        +1,1,0,                  // second point of heart curve

        -1,-h+1,0,
        0,2*h*f,0.5,
        +1,-h+1,0,                // third point of heart curve

        0,-h,0,
        0,-h,0,
        0,-h,0                  // fourth point of heart curve
    };
    if(ShowControlPointsp)
        drawBezierSurfaceControlPoints(U_Order,3,V_Order,3*U_Order,cp);
    
    drawBezierSurface(Wirep?GL_LINE:GL_FILL, U_Order,16,V_Order,16,cp);
 }

GLfloat HeartHeight = 2;

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

    glPushAttrib(GL_ALL_ATTRIB_BITS);

    glColor3f(1,0,0);           // red hearts

    heartHalfCurve(HeartHeight);
    
    glPushMatrix();
    glTranslatef(2,0,0);
    heartHalfSurface(HeartHeight);
    glPopMatrix();

    glPushMatrix();
    glTranslatef(-2,0,0);
    heartWholeSurface(HeartHeight);
    glPopMatrix();

    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);
    if( argc > 1 ) {
        HeartHeight = atof(argv[1]);
    }
    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;
}