/*
 * pickToGo.cpp
 * Pick objects - this program illustrates how to pick objects on the screen and
 * animate them in response.
 *
 *  Created on: Mar 1, 2013
 *      Author: debure
 */

#include <GL/glut.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <iostream>
using namespace std;

#define DTOR 3.14159/180.0
GLfloat theta;
bool sqStart = false,         // booleans for state of each object:
	 sqGrowShrink = false;    // square rotating, square changing size
bool grow = true;             // true if growing, false if shrinking

GLfloat grFactor = 20;        // scale factor for growing square
GLint gsX = 100, gsY = 100;   // center of growing square

GLfloat rsFactor = 50;        // scale factor for rotating square
GLint rsX = 250, rsY = 425;   // center of rotating square


void myinit(void) {

  glClearColor(0.0, 0.0, 0.0, 1.0);
  glColor3f(0.0, 0.0, 0.0);

  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluOrtho2D(0.0, 500.0, 500.0, 0.0);
  glMatrixMode(GL_MODELVIEW);
  glEnableClientState(GL_VERTEX_ARRAY);
}

void display(void) {

  // square is created at the origin
  GLfloat sq_vertices[4][2] = {{-1.0,-1.0},{1.0,-1.0},{1.0, 1.0},{-1.0,1.0}};
  GLubyte sqIndices[4]={0,3,2,1};
  GLfloat colors[8][3] = {{0.0, 0.0, 0.0},{1.0,  0.0, 0.0},
                        {1.0, 1.0, 0.0},{0.0,  1.0, 0.0}, {0.0, 0.0, 1.0},
                        {1.0, 0.0, 1.0},{1.0,  1.0, 1.0}, {0.0, 1.0, 1.0}};

  glClear(GL_COLOR_BUFFER_BIT);
  glVertexPointer(2, GL_FLOAT, 0, sq_vertices);
  glColorPointer(3, GL_FLOAT, 0, colors[2]);
  glEnableClientState(GL_COLOR_ARRAY);

  // code for rotating square
  glPushMatrix();
  glLoadIdentity();
  glTranslatef(rsX, rsY, 0.0);           // center of rotating square
  glScalef(rsFactor, rsFactor, 0.0);
  glRotatef(theta*DTOR, 0.0, 0.0, 1.0);
  glDrawElements(GL_QUADS, 4, GL_UNSIGNED_BYTE, sqIndices);
  glPopMatrix();

  // code for growing square
   glPushMatrix();
   glLoadIdentity();
   glTranslatef(gsX, gsY, 0.0);         // center of grow/shrink square
   glScalef(grFactor, grFactor, 0.0);
   glDrawElements(GL_QUADS, 4, GL_UNSIGNED_BYTE, sqIndices);
   glPopMatrix();

  glutSwapBuffers();
  glFlush();
}

void idle(void){

  if (sqStart){
	  theta += 10;            // modify rotation angle that is used in display
  }
  if (sqGrowShrink){
	  if (grFactor > 100)
		  grow = false;
	  else if (grFactor < -100)
		  grow = true;
	  if (grow)
	     grFactor = grFactor + 0.05;
	  else
		  grFactor = grFactor - 0.05;

  }
  glutPostRedisplay();
}

void mouse(int button, int state, int x, int y){

   if (button==GLUT_LEFT_BUTTON && state==GLUT_DOWN &&
	   x >= gsX-grFactor && x <= gsX+grFactor &&
	   y >= gsY-grFactor && y <= gsY+grFactor){       // check if inside rotating sq
       sqGrowShrink = !sqGrowShrink;
   }
   if (button==GLUT_LEFT_BUTTON && state==GLUT_DOWN &&
	   x >= rsX-rsFactor && x <= rsX+rsFactor && y >= rsY-rsFactor && y <= rsY+rsFactor){  // check if inside scaling square
	   sqStart = !sqStart;                            // already rotating: stop it
   }
   if (button==GLUT_RIGHT_BUTTON && state==GLUT_DOWN)
	   exit(0);
}

int main(int argc, char** argv) {

  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB );
  glutInitWindowSize(500, 500);
  glutInitWindowPosition(0,0);
  glutCreateWindow("Pick to Go");
  glutDisplayFunc(display);
  glutMouseFunc(mouse);
  glutIdleFunc(idle);

  myinit();
  glutMainLoop();
  return 0;
}