[4.5.9] Hide behind tiles while in a specific action step

[m8si]

Found out an easy way to hide an object behind a tile during a specific action step.

In your Subroutines/doDrawSprites.asm find this spot and change the code. In my project it was at line 266

 doDrawSpritesLoop:
    
            LDA (temp16),y
            clc
            ADC temp3
            STA tempC ;; the calculated table position, with offest.
                        ;; tempC becomes the "tile to draw".
            INY
            LDA (temp16),y
            STA tempD ;; the next value is the attribute to draw.
          
            INY         ;; increasing again sets us up for the next sprite.
                        ;; now we can use tempA-D to draw our sprite using the macro.
                        
            ;; MOVE TO BACK m8si **************************************
            
            LDA Object_vulnerability,x
            AND #%00100000                 
            ORA tempD
            STA tempD
            
            ;; MOVE TO BACK m8si **************************************
            
            ;;;;;;;;;;;; Here, we need to evaluate if this tile should be drawn
            ;;;;;;;;;;;; based on the comparison to camX.
            JSR evaluateTileAgainstCameraPosition
            BEQ thisTileIsInCamRange
                JMP thisTileIsOffScreen
            thisTileIsInCamRange       
            DrawSprite tempA, tempB, tempC,tempD

Then make an action step flag "Hide Behind". Note that it has to be Flag 5 or otherwise the code is not going to work.
And that's it. Now just tick that "Hide Behind" for the Action Steps you wish to hide the object behind tiles.



Advanced: if you for some reason need to use other place than "Flag 5" you can always shift the position of the bit with LSR / ASL. Just make sure that you shift the bit to the correct position before AND #%00100000. That is the place of the bit that holds sprite priority. (foreground/background)

Flag 6 for example:

    LDA Object_vulnerability,x
    LSR ;;; Action step is #%01000000 if "Flag 6 is ticked" Shift one to the right so it becomes #%00100000            
    AND #%00100000                     
    ORA tempD
    STA tempD