BDCFF Object 0002: Magic wall
Object number: $0002
Game class: Boulder Dash (by Peter Liepa)
Object name: Magic wall (or Enchanted wall?)
In this document:
Animate: no
Impact explosive: no
Chain explosion action: consumed
Explosion type: n/a
Rounded: no
Attribute format: %00000000 00000000
There are no attributes for this object type. (There is a global attribute, being the state
of the wall: dormant, on or
expired, but that doesn't apply to individual pieces of magic wall.)
When dormant or expired, the magic wall looks like ordinary
brick wall: 
When on, the magic wall animates in a 4-stage animation sequence:

This GIFs show the graphics from the C64 implementation of Boulder Dash (hence the
graphics are 8 double-width pixels wide and 16 pixels high).
Magic wall is inanimate. It doesn't actually do anything by itself, and therefore doesn't interact
with any other objects.
Instead, other objects (boulder, diamond)
interact with magic wall.
Magic wall starts life dormant, and visually looks just like ordinary brick wall,
until a boulder or diamond falls on it. Then all magic wall in the cave gets turned on
for a time: it sparkles in a distinctive way, it makes a continous tinkling sound, and in this time
any boulder or diamond that hits the wall gets changed into a diamond or boulder respectively, and
falls through, making an appropriate diamond sound or boulder sound respectively. After a certain
time has elapsed (the magic wall milling time), the magic wall expires; it goes
back to looking like ordinary brick wall, no longer makes any sound, and any boulder or diamond
that fall on the wall just disappear (but still make the same sound as appropriate).
States of magic wall
- Dormant: Looks just like ordinary brick wall, until a boulder or diamond activates it.
- On: Sparkles, makes sound, and changes boulders and diamonds into diamonds and boulders, until the Magic Wall Milling Time runs out.
- Expired: Looks just like ordinary brick wall; any boulders and diamonds hitting it just disappear but still with a sound.
Objects move two squares in one frame
Note that when a boulder or diamond hits a magic wall (whether on or not), the object effectively
moves two squares in one frame: one moment it's above the wall, the next moment it's two squares
down, below the wall; it's never "inside" the wall. Note also that if there is any
object underneath the wall at the point where the boulder or diamond falls through, the boulder or
diamond is lost (which is sometimes a helpful way of getting rid of excess boulders).
Stationary objects don't fall through
Note that a stationary boulder or diamond sits on a magic wall without falling through or turning it on.
Note also that magic wall isn't "rounded"; boulders and diamonds do not roll off magic wall like they
do brick wall.
See the boulder specification for how boulders (and diamonds) interact with magic wall.
Web page design by Peter Broadribb