////////////////////////////////////////////////////////
//
// 3D sample program
//
// Han-Wei Shen
//
////////////////////////////////////////////////////////

#include <stdio.h>
#include <stdlib.h>

#include <GL/glut.h> 
#include <GL/gl.h>

int press_x, press_y; 
int release_x, release_y; 
float x_angle = 0.0; 
float y_angle = 0.0; 
float scale_size = 1; 

int xform_mode = 0; 

#define XFORM_NONE    0 
#define XFORM_ROTATE  1
#define XFORM_SCALE 2 


////////////////////////////////////////////// 

void draw_cube(float r, float g, float b)
{
  glColor3f(r, g, b); 
  glutSolidCube(1.0);   // draw a solid cube 
  glColor3f(0,0,0); 
  glLineWidth(2); 
  glutWireCube(1.1);    // now draw the outline 
  glLineWidth(1); 
}

//////////////////////////////////////////////////////

void display()
{
  glEnable(GL_DEPTH_TEST); 
  glClearColor(0,0,0,1); 
  glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); 
  
  glMatrixMode(GL_PROJECTION); 
  glLoadIdentity(); 
  gluPerspective(60, 1, .1, 100); 

  glMatrixMode(GL_MODELVIEW); 
  glLoadIdentity(); 
  gluLookAt(0,0,5,0,0,0,0,1,0); 

  glRotatef(x_angle, 0, 1,0); 
  glRotatef(y_angle, 1,0,0); 
  glScalef(scale_size, scale_size, scale_size); 

  draw_cube(0,0,1);

  glutSwapBuffers(); 
}

///////////////////////////////////////////////////////////

void mymouse(int button, int state, int x, int y)
{
  if (state == GLUT_DOWN) {
    press_x = x; press_y = y; 
    if (button == GLUT_LEFT_BUTTON)
      xform_mode = XFORM_ROTATE; 
	 else if (button == GLUT_RIGHT_BUTTON) 
      xform_mode = XFORM_SCALE; 
  }
  else if (state == GLUT_UP) {
	  xform_mode = XFORM_NONE; 
  }
}

/////////////////////////////////////////////////////////

void mymotion(int x, int y)
{
    if (xform_mode==XFORM_ROTATE) {
      x_angle += (x - press_x)/5.0; 
      if (x_angle > 180) x_angle -= 360; 
      else if (x_angle <-180) x_angle += 360; 
      press_x = x; 
	   
      y_angle += (y - press_y)/5.0; 
      if (y_angle > 180) y_angle -= 360; 
      else if (y_angle <-180) y_angle += 360; 
      press_y = y; 
    }
	else if (xform_mode == XFORM_SCALE){
      float old_size = scale_size;
      scale_size *= (1+ (y - press_y)/60.0); 
      if (scale_size <0) scale_size = old_size; 
      press_y = y; 
    }
	glutPostRedisplay(); 
}

///////////////////////////////////////////////////////////////

void mykey(unsigned char key, int x, int y)
{
        switch(key) {
		case 'q': exit(1);
			break; 
		}
}
///////////////////////////////////////////////////////////////

int main(int argc, char** argv) 
{
  glutInit(&argc, argv); 
  glutInitDisplayMode(GLUT_RGB|GLUT_DOUBLE|GLUT_DEPTH); 
  glutInitWindowSize(600,600); 
  
  glutCreateWindow("Han-Wei Shen's 3D hack"); 
  glutDisplayFunc(display); 
  glutMouseFunc(mymouse); 
  glutMotionFunc(mymotion);
  glutKeyboardFunc(mykey); 
  glutMainLoop(); 
}