Any tips/suggestions on creating a crown..like a kings crown with clubs on top in a circle?

Hi TwinSnakes, here is an idea for one method.

I started by drawing a profile for a revolve, in the front view:



Then select this and run Construct / Revolve, the first point of the revolve axis is snapped to the origin, and the second point straight up:



Then I drew a club shaped curve, this was done by drawing one circle centered along the axis, then I used Transform/Copy to make a duplicate of it a little ways down and to the right, mirrored that over, then drew the foot part coming down using Draw curve / Freeform / Control points, mirrored that, then drew a line between the pieces. I selected the circles and used Construct / Boolean / Union to combine those together, then used Edit/Trim on that to trim away the opening for the foot part and then joined all those together. Let me know if you want more details on this part:



Notice how the revolve extends a little bit further down past the bottom of the club. I then drew a horizontal line even with the bottom of the club (this is centered on the origin):



Now select the revolve and use Construct / Boolean / Difference to slice it with the line, it will now be in 2 pieces and you can delete the line:



Next select the club and use Transform / Array / Circular to make rotated copies, here I used 6 copies and then deleted 3 of them:



Then select the upper revolve part and then run Construct / Boolean / Intersection, and then select the clubs. This intersection creates the "spokes" of the crown:



Now select the spokes and the base piece and use Construct / Boolean / Union to fuse them together into one object and voila:



The shape of the initial revolve controls the shape of the spokes a lot - making that initial revolve more flared or wavy or straighter should give you quite a bit of control over the spokes.

Hope this helps, let me know if you need any details on any of these steps.

- Michael

Wow. This tutorial has really sold me on MoI.

By the way Michael, isn't it time you replace your hand-drawn mascot-logo with a 3D render? :)

Ed

Hi Ed,

> Wow. This tutorial has really sold me on MoI.

I was thinking as I was going through it that it made for a pretty good demo, maybe I will do this as one of the video tutorials. It is kind of a good example of how boolean intersection is useful in some situations, instead of focusing only exclusively on boolean difference. Intersection is a little less intuitive than difference, that's why it is good to have some examples like this on where you might use it - basically where it is easier to model the piece you want to keep in the boolean operation, rather than modeling the piece that you want to remove.


Here is a variation with a more curved inward revolve and also an inner piece cut away using boolean difference. The inner piece was done by making an offset curve from the original club curve:



Now if you're using MoI as a companion to a polygon modeling program, the really really cool part is the quality of polygonization you get when saving this out to an OBJ file:



A lot of the parts feel like a carefully hand-optimized mesh.... It's almost like cheating! :)


> By the way Michael, isn't it time you replace your hand-drawn mascot-logo with a 3D render? :)

Hmmm, I don't know I've gotten kind of fond of that guy the way he is! But it would probably be nice to do a 3D version as well at some point. But he's sort of the type of thing that generally works better in a polygon modeler though, since you kind of want to do little pushing and pulling of points to adjust stuff...

- Michael

Ya know..you sure got yourself a little gem of a program here.

This is the start of something really unique in the 3D arena.

Thanks alot for the tip. I'm entered into the CG Talk competition. So I'll probably be back for more help.

-DjD-

EDIT:

It would be nice to have an option to only displacement curve along one axis when projecting it onto a surface. Currently, when the curve is projected, it deforms. An option to maintain its profile and only displace it on one axis instead of two would be nice.

> It would be nice to have an option to only displacement curve along one axis
> when projecting it onto a surface. Currently, when the curve is projected,
> it deforms. An option to maintain its profile and only displace it on one axis
> instead of two would be nice.

Hi Twinsnakes, I'm not quite following this, could you please show an example of what you mean?

Projection should be happening along just one axis already - like in the crown example above when you do a boolean with a planar curve, the curve is projected just in one direction perpendicular to the plane of the curve.

So for example if you switch to the front view, the silhouette of the solid crown pieces line right up with the outline of the club curve.

If you are seeing something deform differently than that, it might be a bug...

- Michael

Well, I think the opposite. I shouldnt be able to line up the curve with the projected curve by looking at it along the projection axis.

As an experiment. I created a cube, then a unit circle curve. I rotate the curve 45 degrees then projected it onto edge of the cube. I then trimmed the circle curve in half, moved it to the edge of the cube, and finally rotated each half into place.

The highlighted portion of the image is my manual projection. The un-highlighted portion is what moi currently does.



I'm thinking the projection should act like the curve is a sticker, and should place it on the surface, just like if I was putting a bumper sticker on the bumper of my car....The sticker should'nt scale but only displace.

And that's why I asked for help. I layed down a club curve, but it looked stretched when I projected it for my crown.

Hi TwinSnakes, well the projection in your example would function like this - starting with a cube and a 45 degree angled circle:



The way the projection currently works is equivalent to the circle being extruded out:




You can see here where the extruded circle intersects with the cube - that's the resulting curves that you currently get.

This is sort of the regular way that projection works - I mean if you had an actual movie projector lined up in that same direction and the movie projector was showing a picture of a circle, you would get the same kind of shape there.


The way you're describing sounds sort of more like a physics based collision type thing like if the curve was made of stiff wire and was moving along that direction and then slammed into the cube and kind of wrapped around it... Unfortunately I don't have anything that will calculate something like that right now, it would be pretty difficult to make that.

> And that's why I asked for help. I layed down a club curve, but it
> looked stretched when I projected it for my crown.

If you can post your .3dm model file with the stretched curves in it, I might be able to give you some ideas...

- Michael

That's a great suggestion none the less - as much as I use projection, I understand it (just as Michael explained it) BUT I have to admit, I've often thought to myself that the resultant projection is "distorted" compared to what I'd really like at times...

It would be nice to have an option like this in the future - I'm not even sure what you'd call it? "Rigid Projection"??

-Will

Thanks Michael. I feel your pain. And sorry if in my post I sounded a like a lil jerk and a whiner.

But, yeah it probably is a rigid projection. And I looked at the javascript, and I can follow it pretty much.

I think you already have the tools we need. We'd need to project a point along an axis and intersect with a surface, we need to be able to calculate the distance between two points on a curve, and we need to be able to constrain by a 3D distance.

It might take a while for the script to process, but, I think it's a great feature and worth a look.

Hi TwinSnakes,

> and we need to be able to constrain by a 3D distance.

This one is the tricky part - on a wavy surface the constraint won't be just by a direct 3D distance between points, it would be by the distance traveled while hugging the surface, kind of like the length traveled by an ant walking along the surface...

On a cube with planar surfaces, everything is a lot easier... For working with just any surface at all things get way more complicated.

On top of this I see a lot of other difficulties - there would be cases where the rigid curve would actually not completely follow along a surface to maintain its same length. Like imagine a pocketed surface like a golf ball - if you try to apply a bumper sticker to a golf ball, the sticker is not going to completely hug along the entire surface of the golf ball, it won't touch the surface when it goes over one of the dimples. So just walking along the surface directly won't really give the proper result.

Also imagine taking the bumper sticker and trying to wrap it around the eraser end of a pencil - the sticker will kind of gather up and bunch together...

It seems like a pretty difficult problem.

- Michael