Preventing phantom floors? Lining up prims precisely.

OK, I'm building my first large structure right now - a 20 Meter wide, t-shaped Tavern that requires three seperate prims for the floor on each level. The initial form of the structure was made by creating one third of the ground floor, and slide-duplicating and rotating the first piece to form a t-shape. Then I linked and slide-duplicated that floor, moving it up to make the second floor. Walls and interior details were adjusted as needed from there. And part of that involved moving or re-sizing the upper floor prims slightly smaller, so they don't show through the sides of the building, and to allow for a stairway ramp to provide access to the upstairs.

Like many builders, I ran into the glitch where two slightly-overlapping floor prims caused one of my upstairs floor prims to become intangible, causing anyone who steps onto it to fall through to the floor below. Fortunately, information I had already read here in these Forums indicated that an overlapping prim was the problem, and with some fiddling and streaching, I was able to fix it. The floors work now, but none of the prims are quite the same size any more. And the seams now show, just slightly.

On to my questions:

Is there a simple and reliable way to duplicate a floor section prim, such that they end up exactly edge-to-edge, touching but NOT overlapping each other?

Or if you've already duplicated two floor sections, what is the best way to line them up precisely?

Is there a way to 'nudge' a prim, or a linked collection of prims, just a tiny amount at a time, until two prims touch? Does that have to be done by entering tiny incremental numeric values in the object details while editing?

Thanks in advance for the advice!

Use the "copy selection" checkbox in the create menu, and I think the second option, "align" or such - not the "rotate" one. Select the prim you want to duplicate, then check "copy selection" and touch one of the sides of the prim with the magic wand cursor - it will create a duplicate of the original prim, precisely lined up with the original along the side you touched.



By numbers. Line up the original floor pieces using the grid mode or input boxes so they are at "round" coordinates (i.e. at X 10.0 instead of X 9.789). The size of the floor pieces then gives you the correct offset to align the next piece.



Yes, it can be done by incrementing the numeric values, or by using "snap to grid" and setting the grid to a high resolution (0.1 or 0.05, but if you're working with big prims, that will get visually confusing). I think it's a lot easier though to start by aligning your prims to the grid, and building everything by the numbers, if you're very concerned about precision and alignment.

Position them according to the numbers--that is, put a 10 m prim exactly 10 m away from another 10 m prim and at the same height.

Then adjust your textures to make the seams invisible. Sometimes it also helps if the edges of the prims that butt are the same texture or the same color as the surface, or even alpha.

When I am making a series of prims that need to abut each other exactly, I just turn on the “local” reference from the pull down menu and copy the prim.

Right click the prim to be copied, and then hold down the shift key and drag the prim in the direction you’d like the copy to appear. Then just look for the guide line to tell you when it snaps to the 1x snap point. That should line up the new prim exactly to the end of the last. That’s the easy way for me.

Many thanks to each of you! I look forward to trying these methods once I get off work tonight!

I've never understood the grid, or how people can actually *use* it for accurate measurments. I'm sure it works because people do it all the time, but I've never ever figured it out. The only way I know how to build is by hitting windows-R-calc

Though the copy-selection tip is pretty darn handy for some things, too. Wish I'd known that back when I started out trying to build!

Ok, I am a little fuzzy from my flight from California...

You can use some simple math. Lets say you have two prims that you want to line up edge to edge along their X axis.

Step 1: You take 1/2 the size of the first prim along its X axis and add it to 1/2 the size of the second prim along it's X axis. This will give you the desired distance between the centers of the two prims.

Step 2: You then set the X postion of the second prim to be equal to the X postion of the first prim plus or minus (depending upon which side you want to align the the two prims) the number from Step 1.

This should give you exact alignment. Now if you are starting to deal with really percise sizes that extend to the third decimal place , ex. 8.123; you might need to nudge things. I have not yet had to so far. It's odd that llSetPrimParameter is accurate out to six decimal places, but it looks like you only need three decimal places to lines things up edge to edge without a gap or overlap.

Noel, thank you for that clear explanation. I was trying to get it worked out earlier today and was having a heck of a time accurately figuring out the offset.

Snap to grid can work in some situations. What I tend to do is whats been mentioned

If I'm copying things along the X axis, I just add on however many meters the prim is to the co-ordinates for it.