3D Engine

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"""
  --- 3D Visualizer ---
  - Created by Rohan  -
  -  Created in Repl  -
  ---     Note      ---
  - I had to reduce
    the framerate due
    to freezing.      -
"""

import turtle, math as maths, time

# Error classes,
class ObjectNotFoundError(Exception):
  
  pass

class RendererNotFoundError(Exception):
  
  pass

  

# Helper classes,
class Vector2:

  def __init__(self, x=0, y=0, z=0):
    self.x, self.y = x, y

class Vector3:

  def __init__(self, x=0, y=0, z=0):
    self.x, self.y, self.z = x, y, z

class Object:

  def __init__(self, position=Vector3(), rotation=Vector2(), _id=None):
    self.position, self.rotation, self._id = position, rotation, _id

  VERTICIES = []
  TRIANGLES = []

class Cube(Object):

  VERTICIES = [
    # X,  Y,  Z.
    (-1, -1, -1),
    ( 1, -1, -1),
    ( 1,  1, -1),
    (-1,  1, -1),
    (-1, -1,  1),
    ( 1, -1,  1),
    ( 1,  1,  1),
    (-1,  1,  1)
  ]

  TRIANGLES = [
    #P1,P2,P3
    (0, 1, 2), (2, 3, 0),
    (0, 4, 5), (5, 1, 0),
    (0, 4, 3), (4, 7, 3),
    (5, 4, 7), (7, 6, 5),
    (7, 6, 3), (6, 2, 3),
    (5, 1, 2), (2, 6, 5)
  ]

class Camera(Object):

  def __init__(self, position=Vector3(), rotation=Vector2(), fov=400, _id=None):
    self.position, self.rotation, self._id = position, rotation, _id
    self.fov = fov

class Scene:

  def __init__(self):
    self.camera = None
    self.objects = {}
  
  def set_camera(self, cam):
    self.camera = cam

  def add_object(self, obj):
    if obj._id == None:
      obj._id = len(self.objects)
    self.objects[obj._id] = obj
  
  def del_object(self, _id):
    if _id in self.objects:
      del self.objects[_id]
    else:
      raise ObjectNotFoundError('Could not find object with specified `id` in scene!')

  def find(self, _id):
    if _id in self.objects:
      return self.objects[_id]
    else:
      raise ObjectNotFoundError('Could not find object with specified `id` in scene!')

  def get_all(self):
    return self.objects.values()

class Project:

  def project(self, x, y, z, obj, camera):
    x, y, z = self.rotate3d(x, y, z, obj.rotation.x, obj.rotation.y)
    x, y, z = x - camera.position.x, y - camera.position.y, z - camera.position.z
    f = camera.fov / z
    sx, sy = x * f, -y * f
    return sx, sy

  def rotate2d(self, x, y, rot):
    s, c = maths.sin(rot), maths.cos(rot)
    return x * c - y * s, \
           x * s + y * c
  
  def rotate3d(self, x, y, z, rx, ry):
    x, z = self.rotate2d(x, z, rx)
    y, z = self.rotate2d(y, z, ry)
    return x, y, z

class Engine:

  def __init__(self, init_callback=None, update_callback=None, draw_callback=None):
    self.pointer = turtle.Turtle()
    self.pointer.tracer(0, 20)
    self.pointer.speed(0)
    self.pointer.ht()
    self.init_callback, self.update_callback, self.draw_callback = \
      init_callback, update_callback, draw_callback
    
    self.project = Project()
    self.scene = Scene()

  def line(self, p1, p2):
    self.pointer.penup()
    self.pointer.goto(p1)
    self.pointer.pendown()
    self.pointer.goto(p2)

  def draw(self):
    self.pointer.clear()
    if self.scene.camera != None:
      for obj in self.scene.get_all():
        for tri in obj.TRIANGLES:
          POINTS = []
          for vert in (obj.VERTICIES[tri[0]],
                      obj.VERTICIES[tri[1]],
                      obj.VERTICIES[tri[2]]):
            x, y, z = vert
            POINTS.append(self.project.project(x, y, z, obj, self.scene.camera))
          self.line(POINTS[0], POINTS[1])
          self.line(POINTS[1], POINTS[2])
          self.line(POINTS[2], POINTS[0])
      self.pointer.update()
    else:
      raise RendererNotFoundError('No camera set!')
  
  # Run callbacks,
  def cycle(self):
    if self.update_callback != None:
      self.update_callback()

    if self.draw_callback != None:
      self.draw_callback  ()

  def mainloop(self):
    if self.init_callback != None:
      self.init_callback  ()
    while True:
      self.cycle()
      time.sleep(1.0 / 60.0)

if __name__ == '__main__':
  def demo_init():
    demo.scene.set_camera(
      Camera(Vector3(0, 0, -5))
    )
    demo.scene.add_object(
      Cube()
    )
  
  def demo_update():
    demo.scene.objects[0].rotation.x += 0.025
    demo.scene.objects[0].rotation.y += 0.025
  
  def demo_draw():
    demo.draw()
  
  demo = Engine(demo_init, demo_update, demo_draw)
  demo.mainloop()