Routines
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37459: Reveal Dartboard
Used by the routine at MainMenu.
Input
DE Dart pointer co-ordinates
Creates a "zipper" transition effect that reveals the dartboard from the selected menu item expanding both upwards and downwards simultaneously.
The zipper trails behind the dartboard pointer.
RevealDartboard 37459 DEC E Move one position left to start the reveal.
37460 LD (39609),DE Store this position to *ZipperPosition_Upper.
37464 INC D Move one position down.
37465 LD (39611),DE Store this position to *ZipperPosition_Lower.
Process the upper half of the reveal.
RevealDartboard_Loop 37469 LD DE,(39609) DE=*ZipperPosition_Upper.
37473 LD A,E Jump to RevealDartboard_Done if E becomes negative (if it's gone past the left edge).
37474 AND A
37475 JP M,RevealDartboard_Done
37478 PUSH DE Stash the upper position on the stack.
37479 LD A,D Jump to UpperReveal_Done if D becomes negative (if it's gone past the top of the screen).
37480 AND A
37481 JP M,UpperReveal_Done
Set up the right-shifting mask for the upper reveal.
Self-modifying code;
RevealDartboard_ModifyMaskForUpper 37484 LD HL,37575 Set the mask value to 255 at *37575.
37487 LD (HL),255
RevealDartboard_ModifyToShiftRight 37489 LD HL,37581 Write SRL C (203+57) to *Reveal_ShiftCommand.
37492 LD (HL),203
37494 INC HL
37495 LD (HL),57
37497 CALL ProcessRevealLine Call ProcessRevealLine.
UpperReveal_Done 37500 POP DE Restore the original upper position from the stack.
37501 DEC D Move up one line and left one column for the next upper reveal position.
37502 DEC E
37503 LD (39609),DE Store the updated upper position at *ZipperPosition_Upper.
Process the lower half of the reveal.
37507 LD DE,(39611) DE=*ZipperPosition_Lower.
37511 LD A,D Jump to RevealDartboard_Done if D is greater than or equal to 24 (if it's gone past the bottom of the screen).
37512 CP 24
37514 JR NC,RevealDartboard_Done
Set up the left-shifting mask for the lower reveal.
37516 PUSH DE Stash the lower position on the stack.
Self-modifying code;
RevealDartboard_ModifyMaskForLower 37517 LD HL,37575 Set the mask value to 1 at *37575.
37520 LD (HL),1
RevealDartboard_ModifyToShiftLeft 37522 LD HL,37581 Write SLL C (203+49) to *Reveal_ShiftCommand.
37525 LD (HL),203
37527 INC HL
37528 LD (HL),49
37530 CALL ProcessRevealLine Call ProcessRevealLine.
37533 POP DE Restore the original lower position from the stack.
37534 INC D Move down one line and left one column for the next lower reveal position.
37535 DEC E
37536 LD (39611),DE Store the updated lower position at *ZipperPosition_Lower.
37540 JR RevealDartboard_Loop Jump to RevealDartboard_Loop.
All finished for this frame, so return.
RevealDartboard_Done 37542 RET Return.
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