Uruguay christmas

Author: Antonio Vázquez
Category: Christmas Challenge
System:   Spectrum ZX80
Language: BASIC
Len source code: 175 bytes
Len exe file:    259 bytes
Len code only:   175 bytes
Instructions:  load "" y run en emulador
Description:
Three lines are made that intersect, taking advantage of the rebound effect when reaching negative values on both axes, the positive missing bounce is added with a conditional sum.

example of the first bounce:
start at the left edge of the image
When crossing y=0 the line makes an apparent rebound
----------
!      *
!     * * 
!        * <-- start from here
!       
second rebound
--------------
!     *
!    * *
!   *   
!  *    
! *
!*
! *  
third bounce, here we look for the index where
it must be bounced and a recovery operation is applied
conditional subtraction subtracting double the
difference -(2*n and i>10)
--------------
!     *
!    * *
!   *   *
!  *
! *
!*   *
! * * 
!  *


Comments:
The challenge was very fun, thank you!!