import time, math
from pyglet.gl import *

window = pyglet.window.Window()

class AlphaSquare:
    def __init__(self, moveradius, color):
        self.moveradius = moveradius
        self.xpos = 0
        self.ypos = 0
        self.color = color
        self.vlist = pyglet.graphics.vertex_list(4, ('v2f', [-128,-128, 128,-128, -128,128, 128,128]))
    def draw(self):
        glEnable(GL_BLEND)
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
        glColor4f(self.color[0],self.color[1],self.color[2],self.color[3])
        glPushMatrix()
        glTranslatef(self.xpos, self.ypos, 0)
        self.vlist.draw(GL_TRIANGLE_STRIP)
        glPopMatrix()
        glDisable(GL_BLEND)
    def update(self,dt):
        self.xpos = self.moveradius * math.sin(time.time())
        self.ypos = self.moveradius * math.cos(time.time())


objects = []
objects.append( AlphaSquare(0, [1, 1, 1, 1]) )
objects.append( AlphaSquare(128, [1,0,0, 0.5]) )


@window.event
def on_draw():
    glClearColor(0, 0.3, 0.5, 0)
    glClear(GL_COLOR_BUFFER_BIT)
    
    glLoadIdentity()
    glTranslatef(320,240,0)

    for o in objects:
        o.draw()


def update(dt):
    global objects
    for o in objects:
        o.update(dt)
    objects[1].color[3] = (1+math.sin(time.time()))/2.0


pyglet.clock.schedule_interval(update,1/60.0)
pyglet.app.run()