getting the current color of the visible pixel in the pygame module

I am using PYgame to create an environment with multiple cars. etch car has its own radar where it can check the distance between obstacles. the problem that I am having is, how to get the color of a pixel. so if a moving car has the color purple and it is currently over the [x,y] Pixsle I will get the purple cooler not the surface color of the picture screen.

current logic for the radars:

    while not WIN.get_at((x, y)) == pygame.Color(48, 48, 48, 255) and length < 80:
        length += 1
        x = int(xcenter + math.sin(-math.radians(self.angle + radar_angle)) * length)
        y = int(ycenter - math.cos(-math.radians(self.angle + radar_angle)) * length)

    pygame.draw.line(WIN, (255, 255, 255, 0), (xcenter,ycenter), (x, y), 1)
    pygame.draw.circle(WIN, (0, 255, 0, 0), (x, y), 2)
    pygame.display.flip()

this code works great with the screen image.

but not so great with other cars

do there is a function in pygame that handles this case?

Answer

You have to options.

1. Do the opposite. Test if the color is the gray color of the street:

   street_gray = (128, 128, 128) # use your gray street color here
   
   while WIN.get_at((x, y)) == street_gray and length < 80: 
       # [...]
   

2. Use a pygame.mask.Mask that is 1 at positions of obstacles and 0 elsewhere. When you create the mask you need to set the set_colorkey() for the gray road. The mask can be created with pygame.mask.from_surface. pygame.mask.Mask.get_at returns either 0 or 1:

   win_surf = WIN.copy()
   win_surf.set_colorkey(street_gray)
   street_mask = pygame.mask.from_surface(win_surf)
   
   while street_mask.get_at((x, y)) == 0 and length < 80: 
      # [...]