Monsters and stairs

[40oz]

What determines a monsters ability to walk over stairs and short ledges? I noticed some stair sets monsters walk up and down with ease, some where monsters have trouble walking up but no problem walking down, and some that block their movement up and down completely without the use of monster block lines.

How can I make my stairs look cool but still be monster friendly?

[printz]

Each monster has a specific width. They're all enclosed in bounding boxes actually. If by trying to step over a stair (ledge), any part of their bounding box would become suspended in air more than 24 units above ground, the movement won't happen.

In effect, most regular Doom monsters won't be able to pass 16-tall 32-deep stairs like the E1M1 start, because they're 40 units wide, and if they try moving, a part of their bounding box would always be 2*16=32 units above the next step, therefore no walking.

[EarthQuake]

40oz said:

How can I make my stairs look cool but still be monster friendly?

You can always make your monsters stair-friendly with DeHackEd!
It does carry the possibility of making monsters harder to hit, but I think just cutting down the radius by a small amount really makes a big difference.

Also something neat worth looking into if you're wanting to improve monsters behavior is the DROPOFF thing flag. This is normally used to make flying monsters move across ledges, but if applied to a non-flying creature, they will drop off of ledges. The effect is vanilla is a "snapping" to the ground, as where in ports that support actors-over-actors, they seem to "jump" off, which is really cool looking.

Try a combination of these. In vanilla, you can limit the DROPOFF monsters to areas with really low ledges, so the snapping isn't so apparent. Any higher ledges you can just place monster blocking lines on.

[printz]

Don't forget the TELEPORT flag. It also works on players and is similar to Dark Forces' LAPOGO cheat. Monsters also need DROPOFF for TELEPORT to work, however.

If you're using PrBoom, MBF or Eternity, use BOUNCES+FLOAT to make jumping monsters. Add DROPOFF to the really badass jumpers.

To answer the same question that EarthQuake quoted:
If you're using PrBoom, MBF or Eternity (again...), there's a simple monster compatibility option that lets them walk ANY stair angle.

[Gez]

printz said:

If you're using PrBoom, MBF or Eternity, use BOUNCES+FLOAT to make jumping monsters. Add DROPOFF to the really badass jumpers.

This should work in G/ZDoom too. (But not Skulltag.)