#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <unistd.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <gl.h>
#include "globals.h"
#include "util.h"

/* sets up the viewport */
void set_viewport(RenderState state)
{
  int vp_left, vp_right, vp_bottom, vp_top;
  
  win_stat(state.winview, state.orgview, state.sizeview);

  vp_left = 0;
  vp_right = state.sizeview[X];
  vp_bottom = 0;
  vp_top = state.sizeview[Y];

  viewport(vp_left, vp_right, vp_bottom, vp_top);
}

/* sets up the views, either in perspective of parallel projection */
void set_view(RenderState state)
{
  float aspect_ratio;

  aspect_ratio = ((float)state.sizeview[X])/((float)state.sizeview[Y]);

  /* perpective */
  if (state.persp)
    {
      if (state.stereo_on)
	{
	  perspective(state.angle, 0.5*aspect_ratio,
		      state.near, state.far);
	}
      else
	{
	  perspective(state.angle, aspect_ratio,
		      state.near, state.far);
	}
    }
  /* parallel */
  else
    {
      ortho(state.left*(1.0/aspect_ratio), state.right*(1.0/aspect_ratio),
	    state.bottom, state.top,
	    state.near, state.far);
    }

  lookat(state.cop[X]-state.dcop[X], state.cop[Y], state.cop[Z],
	 state.vrp[X], state.vrp[Y], state.vrp[Z],
	 10.0*(state.twist));
}

/* applies the transformations to the cumulitative matrix */
void transformations(RenderState state)
{
  translate(state.dx, state.dy, state.dz);
  scale(state.scale_factor, state.scale_factor, state.scale_factor);

  if (state.auto_wobble)
    {
      float speed;  /* factor to produce reasonable wobble speed */
      speed = 10.0*elapsed_time(&state.run_time);
      if (gstate.wobble_amplitude >= 90.0)
        { /* do continuous rotation */
          rot(50.0*(speed/state.wobble_period) - state.init_wobble_angle, 'y');
        }
      else
          rot(state.wobble_amplitude*sin(speed/state.wobble_period) - state.init_wobble_angle, 'y');
    }

  multmatrix(cm);
}

/* updates the cumulitative matrix */
void updatematrix(RenderState state)
{
    pushmatrix();
    loadmatrix(id);

    switch (state.axis)
      {
      case (XY_AXIS):
	state.txr = fmodf(state.xrot+state.txr, 360.0);
	state.tyr = fmodf(state.yrot+state.tyr, 360.0);
	rot(state.xrot, 'x');
	rot(state.yrot, 'y');
	break;

      case (Z_AXIS): 
	state.tzr = fmodf(state.zrot+state.tzr, 360.0);
	rot(state.zrot,'z');
	break;

      case (NO_AXIS):
	break;
	
      default:
	break;
      }
    
    multmatrix(cm);
    getmatrix(cm);
    popmatrix();
}

/* returns the theta angle in polar coordinates between the
   two vectors v1 and v2 */
float get_theta(float *v1, float *v2)
{
  float angle, rad;
  float v[3] = {v2[X]-v1[X], v2[Y]-v1[Y], v2[Z]-v1[Z]};

  rad = distance(v1, v2);
  if (rad == 0.0)
    return 0.0;

  angle = asin(v[Y]/rad);
  return angle;
}

/* returns the phi angle in polar coordinates between the
   two vectors v1 and v2 given the theta angle */
float get_phi(float *v1, float *v2, float t)
{
  float angle, rad, cost;
  float v[3] = {v2[X]-v1[X], v2[Y]-v1[Y], v2[Z]-v1[Z]};

  rad = distance(v1, v2);
  if (rad == 0.0)
    return 0.0;

  cost = cos(t);

  if (cost)
    angle = acos(v[X]/(rad*cost));
  else
    angle = 0.0;
  return angle;
}

/* adjusts the twist angle at the north and south poles
   by twisting an extra 180 degrees */
float adjust_twist_angle(float old_theta, float new_theta, float twist_angle)
{
  if ((rad_to_deg(old_theta) > 350.0 && rad_to_deg(new_theta) < 10.0) ||
      (rad_to_deg(old_theta) < -350.0 && rad_to_deg(new_theta) > -10.0))
    {
      return twist_angle;
    }

  if ((rad_to_deg(old_theta) < 90.0 && rad_to_deg(new_theta) >= 90.0) ||
      (rad_to_deg(old_theta) > 90.0 && rad_to_deg(new_theta) <= 90.0) ||
      (rad_to_deg(old_theta) < 270.0 && rad_to_deg(new_theta) >= 270.0) ||
      (rad_to_deg(old_theta) > 270.0 && rad_to_deg(new_theta) <= 270.0) ||
      (rad_to_deg(old_theta) < -90.0 && rad_to_deg(new_theta) >= -90.0) ||
      (rad_to_deg(old_theta) > -90.0 && rad_to_deg(new_theta) <= -90.0) ||
      (rad_to_deg(old_theta) < -270.0 && rad_to_deg(new_theta) >= -270.0) ||
      (rad_to_deg(old_theta) > -270.0 && rad_to_deg(new_theta) <= -270.0))
    {
      return fmodf(twist_angle+180.0, 360.0);
    }
  return twist_angle;
}

/* creates a display list for obj,
   the function display_list must generate
   the display list, and return the number of
   polygons generated by the list */
int make_display_list(Object obj, DisplayList display_list)
{
  int num_polys;
  
  /* if this object already exits, delete it */
  if (isobj(obj))
    delobj(obj);

  /* begin display list */
  makeobj(obj);

  /* generate the display list */
  num_polys = display_list();

  /* end display list */
  closeobj();
  
  /* clean up any fragments */
  compactify(obj);

  return num_polys;
}