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C. Andrew Dunning

Mesh Creation

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Greetings!

I am trying to create a Mesh of an array of extruded arcs. My question: Is this even permissible? I can create the geometry just fine, but Textures applied to the Mesh seem only to be applying to one of the arcs (there are 48).

Am I missing something?

Thanks!

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I think you can only make a mesh of 3D polygons. If you convert the arc to 3D polys first, you should be able to mesh them.

Is it supposed to have holes in it? I can't wrap my brain around how you could have continuous matching edges between a bunch of arcs.

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If all the arcs are similar then use a single symbol. If they are all different then use various class attributes.

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Hi, Andrew - I created some linked arcs (ends coincident), composed them (they became a single polyline), extruded them, converted the extrusion to mesh (tons of facets), and applied a brick texture. The texture applies to the entire mesh, but it's really funky. The mapping scale, rotation and mode need to be tweeked to get an approximation of a brick surface. Cylinder map is best, and it is not great.

Linked arcs composed and extruded, but not converted to mesh, yield a much better brick render.

Is your mesh actually a single object, or is it a group of discrete objects which need to have the texture applied to each one? You might need to compose the various facets into a single object to approximate a continuous surface. Or avoid the mesh and go with NURBS or plain old arc extrusions.

-B

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I've attached 2 files:

FlatMesh is an example of the intent of what I'm trying to do - map a single Texture across the array of objects. That image used 3D Polys.

ArcMesh is the array of the arcs onto which I'm trying to map the Texture. This is the one not working.

FWIW, converting the extrusion to 3D Polys didn't seem to fix things.

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So it is not really a mesh, but rather an array of extrudes.

Could you use the Use World Origin for Z setting to get the texture to map across all the objects? I don't know, but it would be the first thing I would try. VW2009 only.

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Have you tried making one object, applying the texture, and then doing a solid subtraction?

I haven't spent a lot of time on it, but it almost works....

btw, great idea.

michaelk

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Pat -

This is an array that is a mesh. The array is created in a script following a "BeginMesh" call. Using this approach I'm able to map a single Texture across a large number of objects.

FWIW, I had originally taken the approach of individually mapping the Texture to each element in an array - and adjusting the offset appropriately for each. That worked, but VW would choke when I got to a few hundred elements in the array - and I'm needing to be able to map to higher numbers than that.

Is the advice you're offering in-essence doing this, or something different? The closest thing to what you mentioned (that I could find) is one of the settings for "SetTexMapBool." Is this what you're meaning?

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In VW2009, there is an option, settable in the OIP to "Use World Origin" for a texture. It may only be for the Z value.

If you have stacked walls (for instance), this makes sure that you don't end up with half a course of bricks at the top of the first floor and then a full course at the bottom of the second floor.

If it is choking for you on the number of objects, then it probably will not help you.

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Andrew

Yeah... it would get cumbersome with hundreds of "bumps" on one object... And changing the image would get old fast.

What you are trying to do is a fantastic idea. Hope it works.

michaelk

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How about a mask? Create a single surface with bumps and a texture. A second, opaque surface with holes for the bumps sits in front of the textured surface. Or maybe it doesn't even need the holes, just have it pass through the textured object.

-B

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If any of you are interested, here's an update:

If I:

1) Create the set of arcs within a group...

2) Convert the group to 3D polys (and, leave as a group)...

3) Convert the group to a mesh...

Things work.

In trying to follow some of Pat's early advice the problem was that I was trying to create the arcs within a "BeginMesh" VectorScript call. Didn't work so well.

I still have some mapping challenges, but at least I'm getting the texture to map in the first place.

Thanks for the thoughts...

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That is really cool.

In your step one are you creating arcs, grouping and then extruding all of the 2D arcs at the same time within the group?

In my little test I'm not sure if it is mapping accurately or if it is producing a fun house mirror kind of effect.

But the images respond to mapping commands in a pretty predictable way.

Is this going to be a new feature in VideoScreen 4?

michaelk

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I'm sure you've figured this out already....

removing the "backs", "tops", and "bottoms" of the arcs makes the image more recognizable.

.... after you remap it.

michaelk

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Is this going to be a new feature in VideoScreen 4?

Who knows...? I'd hoped something along these lines would have been ready for v2 but a combination of geometry generation and texture mapping challenges have made my hopes take a lot longer to realize than I'd anticipated. The former has been working for a while but the latter has really made my head spin. Every time I got above about 200 or so objects VW just didn't want to play. Things are starting to look up, though...

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Howz about a drape surface over cylinders on a plane? Super-impose a 3d poly to mask out the areas between bumps. Mapping is really good. Drape needs lots of points.

-B

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Nice idea, Mr. Shaw.

And the solid subtraction approach works with a drape surface.

There is still a mapping origin thing to figure out....

michaelk

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Did you end up using mesh objects?

Yup. Whereas VW would choke when tube counts approached 200, using this approach lets me get to over quadruple that. If simpler flat elements, I can get in to the thousands w/o issue.

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That's interesting.

My experience w/ mesh objects is usually with SketchUP or dwg imports - no textures, just wireframe.

I've found that VW chokes just trying to do a flyover or change views. Probably because the unbelievably high object count.

I assume you can control the size and number of mesh objects when you create them.

michaelk

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I haven't tried a fly-over but changing views doesn't appear to be an issue.

Controlling the size and number of the facets in the mesh is part of the challenge and will be a function of how coarse of a mesh my users will find to be acceptable. There is obviously a trade-off between speed/object count and rendering accuracy.

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