import math
from OpenGL.GL import *
from OpenGL.GLU import *
from dusk.defs import defs

pixelsPerUnit = float(defs.get('RPG_CAMERA_PIXELS_PER_UNIT'))
yOffset = float(defs.get('RPG_CAMERA_Z_OFFSET'))
fov = float(defs.get('RPG_CAMERA_FOV'))
scale = 8.0

def setupCamera(vw, vh):
  z = (vh / 2.0) / (
    (pixelsPerUnit * scale) * math.tan(math.radians(fov / 2.0))
  )
  lookAt = ( 0, 0, 0 )
  aspectRatio = vw / vh
  position = lookAt[0], lookAt[1] - yOffset, lookAt[2] + z

  glMatrixMode(GL_PROJECTION)
  glLoadIdentity()
  gluPerspective(fov, aspectRatio, 0.1, 1000.0)
  glMatrixMode(GL_MODELVIEW)
  glLoadIdentity()
  gluLookAt(
    position[0], position[1], position[2],
    lookAt[0], lookAt[1], lookAt[2],
    0.0, 1.0, 0.0
  )