I'm not terribly new to forge but I do have a few questions on merging. 1) The spots were the item merges usually has a bump, as if there is a small gap. Is this normal? 2) I often have to deal with pieces ( 3x1 flat blocks and bridges in particular) fighting for dominance over each other, and it makes the map look really bad. How can I combat this?
For the Z fighting(merge flickering) you can just hold down the crouch button(left joystick) and click) or LB because by doing that you will have moved the block up by such a small amount that it is barely noticeable but it will cause a tiny bump(it won't interfere with gameplay) Also that is probably what is happening with your other problem, the block is a little to high.
1) There's always going to be a slight bump, even when you're using coordinates. 2) That's called Z-fighting. Just slightly lift one piece over the other and it should solve the problem.
you want to avoid these situations as much as possible, but even with the best of planning, things like this do occur, what you can do is what I call (at least for myself) "decaling", where you pick one surface, hold down the Rt (or Lt stick, can't remember off the top of my head) stick and flick the chosen surface out of line enough to where the z-fighting (as it is called) stops. you can also use this method to put patterns on walls, and if you get good enough at it, you can combine different pieces to get different patterns. as for the gap, that is because, while most of the forge objects will line up relatively smoothly, in many cases, the grid system will fail (esp when combining edges, i.e. a block rotated 30* and one that is flat will not line up in the grid system perfectly.) a good way to avoid this is to use pieces specific to the desired angle (inclines) or move them manually. you may want to do the latter as little as possible, as the more things you move manually, the less neatly other parts will fit with it. you also have to realize that the blocks in forge are a lot more complex than they appear at first glance, what looks as a single decal on a rectangle is actually a very complex shape and in your case, you are noticing that the edges are angled off, that is the bump, and usually, you won't have to worry about it unless the bump slows you down dramatically when walking over it. On a final note, some parts (esp the big ones) do not lay on the grid system perfectly, this is most obvious when you have them tilted at odd angles (i.e. 34*) it is always a good idea to take a very good look at each forge piece, so that when you do make maps, there won't be any surprises.
Important note - If you are using the piece-bumping technique to cure z-fighting, you'll want to do it like this: 1. Save and reload the map. This will cause any object rotation (a bug in forge) to occur so you can see how the pieces "settle." 2. Locate any z-fighting and fix using the above-mentioned bump technique; HOWEVER, don't turn on rotation snap - leave that off. And don't rotate the objects at all. Just grab them and bump them up or down (you can also move them around side to side a little bit, as long as the rotation stays the same). 3. Save and reload the map one more time, and verify the spots you fixed still look good.