arm3.py

import numpy as np
import pygame
import pygame.locals

from armpart import ArmPart

black = (0, 0, 0)
white = (255, 255, 255)

pygame.init()

width = 750
height = 750
display = pygame.display.set_mode((width, height))
fpsClock = pygame.time.Clock()

upperarm = ArmPart('upperarm.png', scale=.7)
forearm = ArmPart('forearm.png', scale=.8)
hand = ArmPart('hand.png', scale=1.0)

origin = (width / 2, height / 2)

while 1:

    display.fill(white)

    # rotate our joints
    ua_image, ua_rect = upperarm.rotate(.03) 
    fa_image, fa_rect = forearm.rotate(-.02) 
    h_image, h_rect = hand.rotate(.03) 

        # generate (x,y) positions of each of the joints
    joints_x = np.cumsum([0, 
                          upperarm.scale * np.cos(upperarm.rotation),
                          forearm.scale * np.cos(forearm.rotation),
                          hand.length * np.cos(hand.rotation)]) + origin[0]
    joints_y = np.cumsum([0, 
                          upperarm.scale * np.sin(upperarm.rotation),
                          forearm.scale * np.sin(forearm.rotation), 
                          hand.length * np.sin(hand.rotation)]) * -1 + origin[1]
    joints = [(int(x), int(y)) for x,y in zip(joints_x, joints_y)]

    def transform(rect, base, arm_part):
        rect.center += np.asarray(base)
        rect.center += np.array([np.cos(arm_part.rotation) * arm_part.offset,
                                -np.sin(arm_part.rotation) * arm_part.offset])

    transform(ua_rect, joints[0], upperarm)
    transform(fa_rect, joints[1], forearm)
    transform(h_rect, joints[2], hand)
    # transform the hand a bit more because it's weird
    h_rect.center += np.array([np.cos(hand.rotation), 
                              -np.sin(hand.rotation)]) * -10

    display.blit(ua_image, ua_rect)
    display.blit(fa_image, fa_rect)
    display.blit(h_image, h_rect)

    # check for quit
    for event in pygame.event.get():
        if event.type == pygame.locals.QUIT:
            pygame.quit()
            sys.exit()

    pygame.display.update()
    fpsClock.tick(30)