Basic Scupted PRIM Boards Question

I posted this in the wrong area so this is a re-post. (sorry)

I would like to start building structures that use prims like boards, with angles cut into the ends so they fit together properly without overlap.

For example, say I want to create a building that has one tall prim, one at a 45 degree angle, then one straight accross, then another 45 then back down again. (straight outside walls, and a roof with 2 angles and a flat top)

At home I'd get out the ol' miter saw and cut the angles to match. In SL, it doesn't appear you can cut one end of a prim without going to sculpted prims.. or by being sloppy and just overlapping prims.

I've seen collections of prims for making stairs etc. on slexchange, but these typically have the same angle cut on both ends.

Does anyone have a collection of angle-cut prims for projects like this... or... without getting really fancy, what tool might I use to make simple "boards" or "beams" for my buildings.

Again, nothing fancy like curved ends needed - all straight cuts, nothing you wouldn't accomplish with a miter saw (for example).

If I'm reading you right, you're asking how to bevel one or more edges of a board, right? Well, that's easy. The parameters you want to use are called Taper and Shear.

Take a look at this image for an example of exactly what you described:



The two red blocks are each tapered by 10% and sheared by 5% on the Y axis. Shearing by half the taper amount ensures that one end will be square. In this case, the squared end is the "bottom".

The two blue blocks, and the green block, are tapered by 20% on Y, and not sheared at all. With no shear, both ends of each block are beveled by the same amount, which in this case is 22.5 degrees.

To answer your question about possibly using sculpties for this, the answer is you could, butit would be a huge waste of polygons. Every sculpty has 2048 polys in it. Each cube has just 108. So while this arch could be 4 prims lighter if it were a single sculpty, it would be 5 times heavier in terms of its poly count.

Poly count affects performance more than anything else. It takes 19 cubes to equal the amount of lag caused by one sculpty. So if you can replace 19 cubes in a project with one sculpty, then it's worth it. But not for just four.

Also, the sculpty would take longer to make (not that either mehtod would take all that long), and could potentially have LOD problems when viewed from a distance if it's not made very carefully. And that's before you even get into the physics problems that sculpties have.

Sculpties are great for lots of things, but this isn't one of them.

Oh, and by the way, since you mentioned it, those sculpted staircases are usually not worthwhile either, in my opinion. But that's a whole other discussion.

Hmmm.. interesting! I had played with the shearing but it seemed like my "beams" were bending strange vs. cutting on the end. Perhaps I didn't build the prim up from the base correctly when I was applying the properties so it wasn't acting as it should.

I will test this out. If this can be done without sculpting its the obvious answer i needed. Thanks for this!

Also, there is *usually* nothing wrong with overlapping prims. Just think of it as the SL version of a fine mitre joint.

lee

I must be doing something wrong as this isn't working as you propose.

Here is what I do:

1. Create a simple box.
2. Raise the height, narrow it a bit. (now it looks like a board standing on end)
3. Put in the Y axis taper .10
4. Put in the Y axis shear .05

This tapers all the way across the board, not just at the end as you have pictured.. i.e. the taper starts from the bottom. To get a full taper, I have to input 1.0 and .5 as the inputs. The problem is I end up with a full wedge, not a board with the end cut off. For some reason your taper starts out at the end of the board... what am I missing to get this to happen?

Here is what I end up with...




As for overlapping... I just don't like how it can look strange as you rotate around it, as if the faces are fighting to show through.

Zed, just rotate the cube 90 degrees, and stretch it the other diretion. What you've currently got as the "top" should be inward-facing side. ("Inward", meaning facing into the archway).

As for the visual problems with overlapping, the term you're looking for is Z-fighting, or as most SL'ers call it, "flickering". The flicker can be overcome pretty easily with careful placement of texturing, or if you're a little lazier, by making one piece a little thinner than the other. But generally overlap should be avoided, and that's not that hard to do.

To me, overlap is generally the mark of a sloppy modeler. I won't name any names, but you'd be surprised just how many professionals are lazy enough to live with it, though. Instead of investing the little extra TLC it takes to avoid overlap, they just throw their hands up and say that's how it is in SL. That kind of thing bugs me to no end. There's no excuse not to be precise. But I digress.

I got this to work using the X taper/sheer not the Y, so perhaps try that as well.

Either one will work. You can even do both, if you want the bevel to be on the "sides" as well as the "ends".

Works! Thanks...

Now I need to figure out the formula, as lining these things up is now an even bigger chore.

For example, a prim that is 10 x .3 x 1 with a .06 taper and a .03 top shear doesn't match up with another object the same size with a .04 taper (at a 45 degrees rotation). In fact, the object with the same size actually ends up looking thinner which is odd. If I take the .04 taper and stretch the object to be about 1.125 instead of 1, it *almost* matches up.

Anyone know of a calculator for this? It almost feels like the percentages need another decimal place.