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frankimator

Can I project a helix inward to cut a cone?

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I've got this parametric model that I need to recreate as a poly model, since I want to add a lot of surface detail to make this look like it was constructed from stone and mortar, so I'm thinking I probably need to achieve clean geometry/UVs to be able to paint in those details and add a displacement map to give it more of a textured profile. 

In my "parametric prototype" the central tower is a truncated cone, and the spiral ramp was made with a sweep over a tapered helix.

Is there any way I can project the helix onto the surface of the cone to get even cuts in my vertical edges that follow the spiral? I've tried making a Line cut using a copy of the helix that I made editable, but it does a projection all the way through the cone and I'm getting the opposite side of the helix as a cut on the visible side, even when I check the "visible" box. 

So far, the closest I've gotten to the result I want was just to use a straight line cut with "Visible" checked so that it only cuts from the side of the view I'm in, then switching to another side and making another straight Line cut. But this does not result in a smooth helical line around the surface, so I would have to slide all the new points by hand into their proper vertical positions on the surface, and as far as I can see the Slide tool only works on one point at a time.

I'm hoping there's a way to project the helix toward the center of the tower and make that smooth spiral cut all the way down on all sides.

Am I missing something or is there just no way to do what I'm attempting in Cinema?

 

 

para-proto.png

Screen Shot 2020-03-28 at 4.31.23 PM.png

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You could project spline along tower, simply use Project command from Spline/Move tab and use spherical mode. Maybe it´s not super-exact positioned (since spherical means bit stretched, but almost unvisible.

Be sure you project standard spline (converted to real spline not parametric helix for example) and adjust intermediate points as needed...

 

But if you want make a cut along this spline, I think not posible now. It´s posible to make "projection spline cut", but only perpendicular in viewport (on flat surface)

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To be honest it is probably quicker and easier to create this whole model again from a regular helix spline, some instances of that  and a few deformers and generators. For example the base shapes for both tower and track could be made as follows in about a minute with this sort of setup...

 

image.thumb.png.bad416a6ffcda40948e55488554c6fd2.png

 

So here 2 helix splines (can be parametric) are offset on Y slightly,  then placed under a Loft with a Taper deformer to taper the resulting mesh. That goes inside a connect with a high enough weld threshold to join the surfaces. Now you could copy the splines / Taper, make the connect editable and continue modelling, and use the splines you saved earlier to create the outer track, also via a loft. Subdivision and the loft settings give you immaculate control of segment count and resolution.

 

CBR

 

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On other side, I must correct my post since in this your specific case itś  posible...Because is met condition whole projected spline visible by camera.

If you look to your tower in top view, you could see whole surface of tower and also projected spline...

 

 

...create helix with needed parameters, convert to real spline, adjust scale in Y axis (since projection will be spherical, spline can "overshoot" top of the cone

279844304_splineproject_1.thumb.png.89745d24f487d35a1d60ddffc8867903.png

 

...project spline to surface with Spline/Move/Project with spherical projection

1602163813_splineproject_2.thumb.png.5a055d4040a7933a672ed5002e23dc2c.png

 

... projected spline result

1760350207_splineproject_3.png.84c43a7a311f7140f623d0576abbb6b7.png

 

...switch to top view, select cone object, activate knife line mode (K~K) and with CTRL select cut.

1186152187_splineproject_4.thumb.png.fa625c08bab94d9de3c400686cc491b3.png

 

...knife just edges of polygons and this way are not created new "single" polygons, but n-gons only

1668827407_splineproject_5.thumb.png.2904eb4f94ae429b75083a5facdb2279.png

 

... to solve that use command"remove n-gons"

65692836_splineproject_6.thumb.png.810665e87b16a86dd062abb826507ff7.png

 

...and result

1039810923_splineproject_7.thumb.png.c12545a00f78a4bdb6cc119f4d608bf9.png

 

Maybe there are needed some adjustment of the mesh (slide some edges etc.), but sometimes can be usefull...

 

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Thank you! This is a great solution. 

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Thank you all for your advice and solutions to this. 

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