> Before anything on the scene is stepped, determine whether the character is standing on a moving platform. This can be done by checking, for example, whether

> Before anything on the scene is stepped, determine whether the character is standing on a moving platform. This can be done by checking, for example, whether his center-bottom pixel is just one pixel above the surface of the platform. If it is, store a handle to the platform and its current position inside the character. I implemented a 2D platformer with moving platforms once; we solved this simply by using another rule in the article — the one for ladders: > when you’re in a ladder, you ignore most of the standard collision system, and replace it with a new set of rules. There was a special flag on the entity for "is on a platform" (and which platform, too); thus, you trivially knew if something was on the platform. During normal collision detection, if you found yourself falling through a platform, your fall was truncated, and you were affixed to the platform. (An entity's platform variable became, essentially, Some(a_ref_to_the_platform).) The affixing was two-way, IIRC: the platform knew about you, mainly s.t. when it moved, it could update linked entities. And if it was destroyed — which could happen — then it could unref itself from whatever was on it; really, one had a weakref to the other, but I was not that good a programmer then, so it was more manually implemented. It worked quite well. We tried the whole pixel business, but it was troublesome; the game engine itself needed to deal with characters falling >1px per game state step, so it already knew "you are falling into a platform" bit.