Skip to navigation

Elite on the BBC Micro and NES

Drawing pixels: PX3, Removed

[Elite-A, Flight]

Name: PX3, Removed [Show more] Type: Subroutine Category: Drawing pixels Summary: Plot a single pixel at (X, Y) within a character block
Context: See this subroutine in context in the source code References: No direct references to this subroutine in this source file

This routine is called from PIXEL to set 1 pixel within a character block for a distant point (i.e. where the distance ZZ >= &90). See the PIXEL routine for details, as this routine is effectively part of PIXEL.
Arguments: X The x-coordinate of the pixel within the character block Y The y-coordinate of the pixel within the character block SC(1 0) The screen address of the character block T1 The value of Y to restore on exit, so Y is preserved by the call to PIXEL
\ --- Mod: Code removed for Elite-A: ------------------> \.PX3 \ \ LDA TWOS,X \ Fetch a 1-pixel byte from TWOS and EOR it into SC+Y \ EOR (SC),Y \ STA (SC),Y \ \ LDY T1 \ Restore Y from T1, so Y is preserved by the routine \ \ RTS \ Return from the subroutine \ --- End of removed code ----------------------------->