Routines
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33475: Set Sword Direction
Used by the routine at HandlerSword.
Chooses the sprite of the sword in flight from its velocity. The sprite ID is 56 plus a direction number from 0 to 7 which is worked out in C from the signs of the Y and X velocities of the weapon.
Input
HL The address of the Y velocity of the weapon
SwordDirection 33475 LD C,0 C=0 (the direction number for down).
33477 LD A,(HL) Jump to SwordDirection_Horizontal if the weapon is not moving vertically.
33478 AND A
33479 JR Z,SwordDirection_Horizontal
33481 JP P,SwordDirection_CheckX Jump to SwordDirection_CheckX if the weapon is moving down.
33484 LD C,4 C=4 (the direction number for up).
SwordDirection_CheckX 33486 DEC HL Point HL at the X velocity of the weapon.
33487 LD A,(HL) Fetch the X velocity of the weapon.
33488 AND A Jump to SwordDirection_SetSprite if the weapon is not moving horizontally.
33489 JR Z,SwordDirection_SetSprite
33491 JP P,SwordDirection_Right Jump to SwordDirection_Right if the weapon is moving right.
33494 DEC C Decrease the direction number by one, as the weapon is moving left.
SwordDirection_SetSprite 33495 LD A,C Fetch the direction number.
33496 AND %00000111 Keep only bits 0-2 (there are 8 animation frames).
33498 ADD A,56 Add 56 to point to the correct frame/ sprite ID (the sword base sprite ID is: 56).
33500 LD HL,60056 Point HL at the player weapon at PlayerWeapon.
33503 LD (HL),A Write the new frame/ sprite ID to the weapon.
33504 RET Return.
SwordDirection_Right 33505 INC C Increase the direction number by one, as the weapon is moving right.
33506 JR SwordDirection_SetSprite Jump to SwordDirection_SetSprite to set the sprite of the sword.
The weapon is moving horizontally only.
SwordDirection_Horizontal 33508 DEC HL Point HL at the X velocity of the weapon.
33509 BIT 7,(HL) Jump to SwordDirection_MovingRight if the weapon is moving right.
33511 JR Z,SwordDirection_MovingRight
33513 LD C,6 C=6 (the direction number for left).
33515 JR SwordDirection_SetSprite Jump to SwordDirection_SetSprite to set the sprite of the sword.
SwordDirection_MovingRight 33517 LD C,2 C=2 (the direction number for right).
33519 JR SwordDirection_SetSprite Jump to SwordDirection_SetSprite to set the sprite of the sword.
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