#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#ifdef HAVE_GL_GL_H
#  include <GL/gl.h>
#elif HAVE_OPENGL_GL_H
#  include <OpenGL/gl.h>
#endif
#include <math.h>
#include "camera.h"
#include "globals.h"
#include "vector.h"

static const vector up = {0.0, 0.0, 1.0};

void camera_home(void){
  vector releye;
  anugavis.eye[0] = anugavis.minX;
  anugavis.eye[1] = anugavis.minY;
  anugavis.eye[2] = 0;
  anugavis.focus[0] = anugavis.minX + (anugavis.maxX - anugavis.minX) / 2;
  anugavis.focus[1] = anugavis.minY + (anugavis.maxY - anugavis.minY) / 2;
  anugavis.focus[2] = 0;
  vsub(anugavis.eye, anugavis.focus, releye);
  anugavis.eye[2] = vlen(releye);
}

void camera_pitch(float theta){
  float c = cos(theta);
  float s = sin(theta);
  float x;
  float y;
  float z;
  vector releye;
  vector newreleye;
  vector axis;
  float dot;
  float len;
  vsub(anugavis.eye, anugavis.focus, releye);
  /* Check we're not too near the vertical */
  dot = vdot(up, releye); len = vlen(releye);
  if(((dot > 0.99 * len) && (theta > 0)) ||
     ((dot < -0.99 * len) && (theta < 0))) return;
  /* Calculation from glRotatef manpage. */
  vcross(releye, up, axis);
  vscale(axis, 1.0/vlen(axis), axis);
  x = axis[0]; y = axis[1]; z = axis[2];
  newreleye[0] =
    releye[0] * (x*x*(1-c)+c) +
    releye[1] * (x*y*(1-c)-z*s) +
    releye[2] * (x*z*(1-c)+y*s);
  newreleye[1] =
    releye[0] * (y*x*(1-c)+z*s) +
    releye[1] * (y*y*(1-c)+c) +
    releye[2] * (y*z*(1-c)-x*s);
  newreleye[2] =
    releye[0] * (z*x*(1-c)-y*s) +
    releye[1] * (z*y*(1-c)+x*s) +
    releye[2] * (z*z*(1-c)+c);
  vadd(newreleye, anugavis.focus, anugavis.eye);
}

void camera_strafe(float dist){
  vector releye;
  vector dir;
  vsub(anugavis.eye, anugavis.focus, releye);
  vcross(releye, up, dir);
  vscale(dir, dist/vlen(dir), dir);
  vadd(anugavis.eye, dir, anugavis.eye);
  vadd(anugavis.focus, dir, anugavis.focus);
}

void camera_track(float dist){
  vector dir = {0, 0, 0};
  vsub(anugavis.eye, anugavis.focus, dir);
  dir[2] = 0;
  vscale(dir, dist/vlen(dir), dir);
  vadd(anugavis.eye, dir, anugavis.eye);
  vadd(anugavis.focus, dir, anugavis.focus);
}

void camera_yaw(float theta){
  float c = cos(theta);
  float s = sin(theta);
  vector releye;
  vector newreleye;
  vsub(anugavis.eye, anugavis.focus, releye);
  newreleye[0] = releye[0] * c + releye[1] * s;
  newreleye[1] = releye[0] * -1 * s + releye[1] * c;
  newreleye[2] = releye[2];
  vadd(newreleye, anugavis.focus, anugavis.eye);
}

void camera_zoom(float dist){
  vector releye;
  float len;
  vsub(anugavis.focus, anugavis.eye, releye);
  if((len = vlen(releye)) < dist) return;
  vscale(releye, dist/len, releye);
  vadd(anugavis.eye, releye, anugavis.eye);
}