Sights: MoveSights

       Name: MoveSights                                              [Show more]
       Type: Subroutine
   Category: Sights
    Summary: Check for up/down/left/right key presses and move the sights
             accordingly, panning the screen if they go past the screen edges
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * CheckForKeyPresses calls MoveSights


.MoveSights

 JSR MoveSightsSideways \ Check for the left/right keys and move the sights
                        \ accordingly, panning to the left or right if they go
                        \ past the screen edges

 LDA panKeyBeingPressed \ If panKeyBeingPressed contains a key press then one
 BPL sigh1              \ of the left and right keys is being pressed, so jump
                        \ to sigh1 to skip scanning the up and down keys as we
                        \ can only move the sights in one direction at a time

 JSR MoveSightsUpDown   \ Check for the up/down keys and move the sights
                        \ accordingly, panning up or down if they go past the
                        \ screen edges

.sigh1

 JMP DrawSights         \ Jump to DrawSights to draw the sights in their new
                        \ position, returning from the subroutine using a tail
                        \ call