/*****************************************************************
  flag0.cpp
  by Dave Pape
  4 April 2003

*****************************************************************/
#include <stdlib.h>
#include <math.h>
#include <unistd.h>
#include <stdio.h>
#include <GL/glut.h>
#include <GL/gl.h>
#include <dms/dms.h>
#include <vector>
#include "PointMass.h"
#include "Spring.h"

using namespace dms;

void createScene(Object& root);
void drawEverything(void);

void key(unsigned char k, int x, int y);
void specialkey(int k, int x, int y);
void idle(void);


#define COLS 11
#define ROWS 11

PerspCamera camera;
Light light;
Object root;

bool active = false;
bool windActive = false;

vector<PointMass> points;
vector<Spring> springs;
Vector3 gravity(0, -10, 0);
Vector3 wind(25, 0, 0);


int main(int argc, char *argv[])
    {
    int i,j;
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
    glutInitWindowSize(512,512);
    glutCreateWindow(argv[0]);
    
    glutDisplayFunc(drawEverything);
    glutKeyboardFunc(key);
    glutSpecialFunc(specialkey);
    glutIdleFunc(idle);
    
    camera.setPosition(0, 0, 4);
    light.setInfinitePosition(-5, 4, 1);
    for (i=0; i < COLS; i++)
        for (j=0; j < ROWS; j++)
            points.push_back(PointMass(Vector3(i/(float)COLS, 1-j/(float)ROWS, 0)));
    for (j=0; j < ROWS; j++)
        points[j].freezePosition();
    for (i=0; i < points.size(); i++)
        points[i].setDrag(1);
    for (i=0; i < COLS-1; i++)
        for (j=0; j < ROWS; j++)
            springs.push_back(Spring(points[i*ROWS+j], points[(i+1)*ROWS+j], 10000));
    for (i=0; i < COLS; i++)
        for (j=0; j < ROWS-1; j++)
            springs.push_back(Spring(points[i*ROWS+j], points[i*ROWS+j+1], 10000));
#if 1
    for (i=0; i < COLS-1; i++)
        for (j=0; j < ROWS-1; j++)
            {
            springs.push_back(Spring(points[i*ROWS+j], points[(i+1)*ROWS+j+1], 100));
            springs.push_back(Spring(points[i*ROWS+j+1], points[(i+1)*ROWS+j], 100));
            }
#endif
                
    glLineWidth(2);
    
    glutMainLoop();
    return 0;
    }


void drawEverything(void)
    {
    glClearColor(0.5, 0.7, 1.0, 0.0);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glEnable(GL_DEPTH_TEST);
    
    camera.apply();
    
    light.apply();

    root.drawAll();
    
    Color::Red.apply();
    for (int i=0; i < springs.size(); i++)
        springs[i].drawLine();
    
    glutSwapBuffers();

    checkGLError("end-of-frame");
    }


void key(unsigned char k, int x, int y)
    {
    if (k == 27)
        exit(0);
    else if (k == ' ')
        active = !active;
    else if (k == 13)
        windActive = !windActive;
    }


void specialkey(int k, int x, int y)
    {
    if (k == GLUT_KEY_LEFT)
        camera.turn(3);
    else if (k == GLUT_KEY_RIGHT)
        camera.turn(-3);
    else if (k == GLUT_KEY_UP)
        camera.pitch(2);
    else if (k == GLUT_KEY_DOWN)
        camera.pitch(-2);
    else if (k == GLUT_KEY_HOME)
        camera.moveForward(0.25);
    else if (k == GLUT_KEY_END)
        camera.moveForward(-0.25);
    else if (k == GLUT_KEY_PAGE_UP)
        camera.zoom(-1);
    else if (k == GLUT_KEY_PAGE_DOWN)
        camera.zoom(1);
    }


void varyWind(void)
    {
    Vector2 windChange = randomUnitVector2() * 0.25;
    wind[0] += windChange[0];
    wind[2] += windChange[1];
    }


void idle(void)
    {
    int i;
    beginFrame();
    if (active)
        {
        for (i=0; i < points.size(); i++)
            {
            points[i].clearForces();
            points[i].applyForce(gravity);
            if (windActive)
                points[i].applyForce(wind);
            }
        for (i=0; i < springs.size(); i++)
            springs[i].apply();
        for (i=0; i < points.size(); i++)
            points[i].update(deltaTime());
        if (windActive)
            varyWind();
        }
    glutPostRedisplay();
    }