"""
Program		: interference.py
Author		: Gareth "Korruptor" Noyce -- http://www.korruptor.demon.co.uk
Desc		: 

                Yakk, Yakk. Interference Circles, more for the Amiga retro collection... :)

We load an image of concentric circles, whose dimensions are larger than the screen. Using
2 copies of the surfarray of this image; we take screen sized array-slices from each, moving
the offsets around a sin.  As the loaded image is a 2 colour gif, and the effect runs on an 8bit 
display, we can use Numeric's add() to sum the arrays, giving a simple surfarray to a custom
3 colour palette. Nice...

Play with the colours, change the image loaded (I was lazy by making a gif, but it does allow you
to play around with different numbers of circles or random shapes...) and adjust the sines to suit 
your taste....
"""


import pygame, pygame.image
from pygame.surfarray import *
from pygame.locals import *
from Numeric import *

# ------------------------------------------------------------------------------------

RES 		= (320,200)
PI 		= 3.14159
DEG2RAD 	= PI/180


# ------------------------------------------------------------------------------------
def main():
     
    	# Initialise pygame, and grab an 8bit display.
    	pygame.init()
    	screen		= pygame.display.set_mode(RES,0, 8)

        # Setup the palette -- choice of colours is pretty important to getting the effect
        # to work well. Mine aren't that great, but then, this is a quickie ;-)
        colour_map = zeros((256, 3))
        
        # Background colour...
        colour_map[0][0] =255
        colour_map[0][1] =255
        colour_map[0][2] =0

        # Circles, not overlapping...
        colour_map[1][0] =32
        colour_map[1][1] =255
        colour_map[1][2] =89

        # Circles, overlapping...
        colour_map[2][0] =225
        colour_map[2][1] =225
        colour_map[2][2] =148

        screen.set_palette(colour_map)
            
        # Something to write to...
        screen_buffer	= pygame.surfarray.array2d(screen)


        # Load the Base image and make a couple of copies...
    	ring1_surf	= pygame.image.load("ring1.gif")
        ring1_arr 	= pygame.surfarray.array2d(ring1_surf)  
        ring2_arr	= ring1_arr


        xang = 0
        yang = 0
        xang1 = 0
        yang1 = 0

        x = 0
        y = 0
        x1 = 0
        y1 = 0

        # Fruity loops...
        while 1:
    
            # Have we received an event to quit the program?
            for e in pygame.event.get():
                if e.type in (QUIT,KEYDOWN,MOUSEBUTTONDOWN):
                    return


            # Calculate the offsets for the slices of the two images...
            offx = ((RES[0]/18)-10)*sin((xang*DEG2RAD) * 2.7)
            offy = ((RES[1]/13)-10)*cos((yang*DEG2RAD) * 2.5)
            offx1 = ((RES[0]/19)-12)*sin((xang1*DEG2RAD) * 2.2)
            offy1 = ((RES[1]/18)-12)*cos((yang1*DEG2RAD) * 2.5)

            # Increment the positions of the slices...
            x += offx
            y += offy
            x1 += offx1
            y1 += offy1

            xang += 1.2
            yang += 2.1
            xang1 += 1.5
            yang1 += 1.7

            # Cut each slice from it's surfarray: [bp+offset:bp+offset+width, bp+offset:bp+offset+height]
            foo = ring1_arr[40+int(x):40+int(x)+RES[0], 200+int(y):200+int(y)+RES[1]]
            bar = ring2_arr[80+int(x1):80+int(x1)+RES[0], 240+int(y1):240+int(y1)+RES[1]]
            
            # Add the two arrays...
            screen_buffer = add(foo,bar)

            # Show results...
            blit_array(screen, screen_buffer)
            pygame.display.flip()

        # Bye!
        print screen_buffer
        return

# ------------------------------------------------------------------------------------
if __name__ == '__main__': main()
# End of sauce. Pass the chips...