Pointing

From IcehouseOrg
Jump to: navigation, search
The imaginary pointing ray from the red pyramid would not quite strike the yellow one if the ray were a completely straight line, since it would pass through the playing surface. Instead, pointing rays are usually imagined to bend and skim along the surface.

A pyramid is said to be pointing at whatever is in the direct path of its tip, with its imaginary pointing ray passing through other pieces, but bending to skim the playing surface. Lots of games care about where pieces point. Sometimes you need to make a floss call by using a piece of string or dental floss to see where a pyramid points.

Variant definitions

For the purposes of one game or another, there may be other "kinds" of pointing. (For example, in Zendo a Master is free to choose almost any definition of pointing.) Here are a few of the common variants:

  • Pointing straight (the imaginary pointing ray stops at the playing surface)
  • First pointing (the imaginary pointing ray stops at the first piece it hits)
  • Pointing within a limited range (the imaginary pointing ray extends for a limited distance, typically the same length as the pointing pyramid itself)
  • Pointing through one object at another. (Also, one may speak of the second, third, etc. item being pointed at.)

Geeky technical details

The pointing ray is imagined to fall along a normal (perpendicular line) of the base of the pyramid. It is an infinitely long line with one end, which is the tip of the pyramid. (That is, the pointing ray cannot point at its own pyramid or anything inside it.) If the pointing ray intersects the playing surface, it bends to skim along the surface, touching pyramids on the surface along its path. (That is to say, after the bend, a pointing ray can no longer touch a piece which is not touching the playing surface at that point.)

If a pointing ray can bend to skim along the surface, what happens if a pyramid points straight down? Even in controlled laboratory conditions, it is difficult to make a pyramid point absolutely straight down for very long. Imaginary theoreticians suggest that in that special case, the pointing ray simply stops at the surface. Other than that, pointing rays generally are unstoppable.

Your game, of course, is entitled to have pointing rays with other properties. The original Icehouse game uses pointing within a limited range, for example.