Routines
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82C3: Set Sword Direction
Used by the routine at HandlerSword.
Chooses the sprite of the sword in flight from its velocity. The sprite ID is 38 plus a direction number from 00 to 07 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 82C3 LD C,$00 C=00 (the direction number for down).
82C5 LD A,(HL) Jump to SwordDirection_Horizontal if the weapon is not moving vertically.
82C6 AND A
82C7 JR Z,SwordDirection_Horizontal
82C9 JP P,SwordDirection_CheckX Jump to SwordDirection_CheckX if the weapon is moving down.
82CC LD C,$04 C=04 (the direction number for up).
SwordDirection_CheckX 82CE DEC HL Point HL at the X velocity of the weapon.
82CF LD A,(HL) Fetch the X velocity of the weapon.
82D0 AND A Jump to SwordDirection_SetSprite if the weapon is not moving horizontally.
82D1 JR Z,SwordDirection_SetSprite
82D3 JP P,SwordDirection_Right Jump to SwordDirection_Right if the weapon is moving right.
82D6 DEC C Decrease the direction number by one, as the weapon is moving left.
SwordDirection_SetSprite 82D7 LD A,C Fetch the direction number.
82D8 AND %00000111 Keep only bits 0-2 (there are 8 animation frames).
82DA ADD A,$38 Add 38 to point to the correct frame/ sprite ID (the sword base sprite ID is: 38).
82DC LD HL,$EA98 Point HL at the player weapon at PlayerWeapon.
82DF LD (HL),A Write the new frame/ sprite ID to the weapon.
82E0 RET Return.
SwordDirection_Right 82E1 INC C Increase the direction number by one, as the weapon is moving right.
82E2 JR SwordDirection_SetSprite Jump to SwordDirection_SetSprite to set the sprite of the sword.
The weapon is moving horizontally only.
SwordDirection_Horizontal 82E4 DEC HL Point HL at the X velocity of the weapon.
82E5 BIT 7,(HL) Jump to SwordDirection_MovingRight if the weapon is moving right.
82E7 JR Z,SwordDirection_MovingRight
82E9 LD C,$06 C=06 (the direction number for left).
82EB JR SwordDirection_SetSprite Jump to SwordDirection_SetSprite to set the sprite of the sword.
SwordDirection_MovingRight 82ED LD C,$02 C=02 (the direction number for right).
82EF JR SwordDirection_SetSprite Jump to SwordDirection_SetSprite to set the sprite of the sword.
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