pygame 3d cube.py

import pygame;
import math;

pygame.init();
pygame.display.init();
pygame.display.set_mode(size=(600,400));

to_render = [
  # bottom edge
  [(0,0,0), (0,0,1), (1,0,0)], 
  [(1,0,1), (1,0,0), (0,0,1)],

  # left edge
  [(0,0,0), (0,1,0), (0,0,1)],
  [(0,1,1), (0,0,1), (0,1,0)],

  #right edge
  [(1,0,0), (1,0,1), (1,1,0)],
  [(1,1,1), (1,1,0), (1,0,1)],

  # front edge
  [(0,0,0), (1,0,0), (0,1,0)],
  [(1,1,0), (0,1,0), (1,0,0)],

  # back edge
  [(0,0,1), (0,1,1), (1,0,1)],
  [(1,1,1), (1,0,1), (0,1,1)],

  #top edge
  [(0,1,0), (1,1,0), (0,1,1)], 
  [(1,1,1), (0,1,1), (1,1,0)],
];

def v_length(v):
  return math.sqrt(v[0]*v[0] + v[1]*v[1] + v[2]*v[2]);
def normalize(v):
  l = v_length(v);
  if(l == 0):
    return [0, 0, 0];
  return [
    v[0]/l, 
    v[1]/l, 
    v[2]/l
  ];
def dot(a,b):
  return a[0]*b[0] + a[1]*b[1] + a[2]*b[2];
def cross(a,b):
  return [
    a[1]*b[2] - a[2]*b[1],
    a[0]*b[2] - a[2]*b[0],
    a[0]*b[1] - a[1]*b[0]
  ];
def sub(a,b):
  return [
    a[0] - b[0],
    a[1] - b[1],
    a[2] - b[2],
  ];

normal = [0, 0, -1];
normal = normalize(normal);

def draw_triangle(color, p1, p2, p3):
  # "shader"
  trig_normal = normalize(cross(sub(p2, p1), sub(p3, p1)));
  diff = dot(normal, trig_normal);
  if(diff < 0):
     diff = 0;
  diff = math.pow(diff, .2);
  new_color = color;
  new_color.r = int(diff * 255.0);
  new_color.g = int(diff * 255.0);
  new_color.b = int(diff * 255.0);
  new_color.a = int(diff * 255.0);
  
  # screen coords
  ws = pygame.display.get_window_size();
  ww = ws[0];
  wh = ws[1];
  fp1 = (ww*(p1[0] + 0.5), wh - wh*(p1[1] + 0.5));
  fp2 = (ww*(p2[0] + 0.5), wh - wh*(p2[1] + 0.5));
  fp3 = (ww*(p3[0] + 0.5), wh - wh*(p3[1] + 0.5));

  # rendering /without depth buffer/
  pygame.draw.lines(pygame.display.get_surface(), new_color, True, (fp1, fp2, fp3));

def scale_point(point, by):
  result = [0,0,0];
  result[0] = point[0] * by[0];
  result[1] = point[1] * by[1];
  result[2] = point[2] * by[2];
  return result;

def rotate_point_y(point, angle):
  result = [0,0,0];
  s = math.sin(angle);
  c = math.cos(angle);
  result[0] = +point[0]*c +point[2]*s;
  result[1] = +point[1];
  result[2] = -point[0]*s +point[2]*c;
  return result;

def offset_point(point, by):
  result = [0,0,0];
  result[0] = point[0] + by[0];
  result[1] = point[1] + by[1];
  result[2] = point[2] + by[2];
  return result;

def ortho(point):
  ws = pygame.display.get_window_size();
  result = [0,0,0];
  result[0] = (point[0] / ws[0]) - 0.5;
  result[1] = (point[1] / ws[1]) - 0.5;
  result[2] = point[2];
  return result;

n = 0.1;
f = 1000;
fov = math.radians(90);
def persp(point):
  ws = pygame.display.get_window_size();
  ar= ws[1] / ws[0];
  ox = point[2]*math.tan(fov/2);
  oy = ox*ar;
  result = [0,0,0];
  result[0] = (point[0] - ws[0]*0.5) / ox;
  result[1] = (point[1] - ws[1]*0.5) / oy;
  result[2] = (point[2] - n) / (f-n);
  return result;

t = 0;
def render_cube(color, position, size, list):
  for triangle in list:
    transformed = [[0,0,0],[0,0,0],[0,0,0]];
    for i in range(0, len(transformed)):
      transformed[i] = triangle[i];
      # model
      transformed[i] = offset_point(transformed[i], (-0.5, -0.5, -0.5));
      transformed[i] = scale_point(transformed[i], (0.5, 0.5, -0.5));

      # world
      transformed[i] = rotate_point_y(transformed[i], t);
      transformed[i] = scale_point(transformed[i], size);
      transformed[i] = offset_point(transformed[i], position);
      
      # projection
      transformed[i] = persp(transformed[i]);
      #transformed[i] = ortho(transformed[i]);
    ###
    draw_triangle(color, transformed[0], transformed[1], transformed[2]);

left=False;
right=False;
while True:
  pygame.display.get_surface().fill((0,0,0));
  render_cube(pygame.Color(255, 255, 255, 255), (300, 200, 20), (10, 10, 10), to_render);
  #render_cube(pygame.Color(255, 255, 255, 255), (300, 200, 10), (600, 400, 300), to_render);
  pygame.display.flip();
  exit=False;
  while(True):
    e = pygame.event.poll();
    if(e.type == pygame.NOEVENT):
      break;
    elif(e.type == pygame.QUIT):
      exit=True;
    elif(e.type == pygame.KEYDOWN):
      if(e.unicode == 'a'):
        left = True;
      elif(e.unicode == 'd'):
        right = True;
    elif(e.type == pygame.KEYUP):
      if(e.unicode == 'a'):
        left = False;
      elif(e.unicode == 'd'):
        right = False;
  if(exit):
    break;
  
  if(left):
    t -= 0.0007;
  elif(right):
    t += 0.0007;
pygame.quit();