Irda Ranger said:
How do Hex-gridders deal with edges of the map? Most buildings have straight walls, which is why I use squares.
Has anyone really (fully) integrated the hex-grid into 3.5's combat system? How many house rules are necessary? Any trade-offs? They might be useful out in "natural" environments, thought I don't really see a strong need.
Your straight wall buildings are probably also limited to least common denominator sizes of 5 feet as well. DND 3E has really conditioned people that rooms with dimensions divisible by 5 in rectangular shaped areas is the way to play the game.
Other people have given you the link to the creature size and area effect for hexes (I would never play facing with hexes as per that link though). So, that shows you the rules necessary for those, but I will list them anyway:
1) A small/medium creature takes up one hex. A large takes up 3 hexes. A huge is a small/medium plus every hex around it for 7. A gargantuan takes up a large plus every hex around it for 12, etc.
2) Each 5 foot radius area of effect (burst or spread) takes up one hex more around a single hex. So, a 5 foot radius is 7 hexes, a 10 foot radius is 19 hexes, etc. Note: this makes the radius a bit large. To make it more accurate, one could use the vertex instead of a hex as the center point and use the creature sizes. 5 foot radius is large creature size, 10 foot radius is gargantuan creature, etc. However, some people might have trouble envisioning that for large area of effect.
3) Each 60 degree cone goes up two of the row axes. Note: there are other options here as well. A 30 degree cone is possible going up a spline and a row. A 60 degree cone can up up two splines instead of two axes.
4) Now to the meat of your question. First off, both hexes and squares can be used for any shape and size room. People should not limit themselves to rectangles with 5 foot LCDs. However, hexes work a little bit better with this regard. The basic rule for combat is: if the hex (or group of hexes for larger creatures) shows 50% or more, a creature can be there and fight. If the hex shows 25% or more, a creature can squeeze there and fight. Note: some DMs might not want to use this second rule for simplicity.
That's most of it in a nutshell. The shape of the room is irrelevant. Square, circle, irregular. It just does not matter.
5) There are a few gotchas that people have to take into account that need special rules. If there is a 5 foot wide corridor leading off perpendicular to a row (i.e. along a spline), creatures have to be allowed to travel into a hex, two half hexes, a hex, two half hexes, etc. This also occurs anytime a very narrow corridor exists and it does not go up a row. Creatures also have to be able to fight from within two half hexes in this case.
6) There is one minor limitation of hexes. Movement along a spline allows for straight, slightly off to the right, or slightly off to the left with the same number of hexes moved. What this does is sometimes allow an attacker to move past defenders by picking a different route, but going the same distance. I consider this a minor nuisance at best, but it might bug other people. There does not have to be any special house rules to handle it.
7) To determine cover or concealment, view a line from the center of the starting and ending hexes. If 50% or more of a hex is in front of the target on the side of cover or concealment (including down a spline line), he is covered.
The rules are fairly easy. In fact, easier than "pick a corner of your square, draw a line to any corner of the target square" type rules of 3E.