Zelda_3_Special_Effects.log

Guide to the code of Zelda 3 (A Link to the Past) Special Effects Mechanics




Special Effect 0x07 - Bombs

$0280[0x0A] - ??? timer?
$028A[0x0A] - ???
$0294[0x0A] - gravity indicator
$029E[0x0A] - the bomb's elevation from the ground in pixels
$02A8[0x0A] - fraction part of the bomb's elevation

$0380[0x04?] - carrying status (probably also includes cane of somaria blocks)
	
	 0 means not being carried. 1 to 3 are various stages of the bomb being picked up by Link
	 3 means it is in Link's hands ready to be thrown

$0385,X - nonzero if the bomb is flying through the air (in motion)
$039F,X - countdown timer

	This timer starts at 0xA0 and counts down to 0. At a certain point it causes the bomb to flash
	When it reaches 0 it initiates the explosion sequence

$03B1[0x0A?] - when Link is picking up a bomb, this is a delay timer for the animation frames

$03C0[0x02] used to indicate that this slot is filled with a bomb (or rock fall)
$03C2[0x08] - ???
$03CA[0x0A] - like $0C7C, this is a floor selector for the bomb, but mirrors the less used $0476
$03D5[0x0A] - transition flag indicating that the bomb needs to switch floors
$03E1[0x02?] - ???
$03E4[0x02] - tile type the bomb interacts with  
$03EA[0x0A] - gah
$03F4[0x0A] ???
$03FD - the only thing that seems to set this is the bird (and only indoors oddly enough)

$0BFA[0x0A] - Y coordinate low byte
$0C04[0x0A] - X coordinate low byte
$0C0E[0x0A] - Y coordinate high byte
$0C18[0x0A] - X coordinate high byte
$0C22[0x0A] - Y velocity
$0C2C[0x0A] - X velocity
$0C36[0x0A] - ???
$0C40[0x0A] - ???
$0C54[0x0A] not used?
$0C5E[0x0A] graphical state of the bomb (from 0 to 0x0B each step progresses from normal to fully exploded)
$0C68[0x0A] - 0 or 2?
$0C72[0x0A] - 0x10 if bomb has touched the floor this frame
$0C7C[0x0A] - floor selector
$0C86[0x0A] - the starting point in the OAM buffer for the sprites of the special effect
$0C90[0x0A] - number of sprites the special effects needs * 4 (since each OAM entry is 4 bytes)

	alternates between 0x10 and the direction Link was facing when he laid the bomb ($7E0074)
	Someone please explain why this is needed :(


Special Effect 0x22 - ReceiveItem

    Necessary components that could be encoded in the sprite object data:
    
        -How the object was received
        -What to do when the timer is about to expire
        -What to do when the timer expires (finishing move?)
        -Whether to do an animation sequence
        -Text message with perhaps additional logic for individual types of objects
        -Whether to trigger the boss victory mode (debatable whether this should even part of the object)
        -Additional customized options (e.g. moon pearl transforming Link instantaneously)
        -Sound effects to play either when opened or when the object's counter is at the expiration state