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Show HN: 3D Vector Graphics

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Re: Show HN: 3D Vector Graphics

#11

Post by fogleman »

scrumper wrote: post #9

This looks pretty great, I'll play with it. Can you explain this from the Readme? Unfortunately, it's difficult to compute the joint formed at the boundaries of these combined shapes, so sufficient texturing is needed on the original solids for a decent result. What is hard about computing the joint? Why does texturing help? My question is from a perspective of curious ignorance, not arrogance (i.e. me saying "don't…

The texturing just helps your eye "fill in the gaps." As far as difficulty, I just don't know of a general way to do it. The only thing that comes to mind is some sort of iterative approximation or something.

Re: Show HN: 3D Vector Graphics

#12

Post by f2f »

scrumper wrote: post #9

This looks pretty great, I'll play with it. Can you explain this from the Readme? Unfortunately, it's difficult to compute the joint formed at the boundaries of these combined shapes, so sufficient texturing is needed on the original solids for a decent result. What is hard about computing the joint? Why does texturing help? My question is from a perspective of curious ignorance, not arrogance (i.e. me saying "don't…

unless you're dealing with sufficiently large integers computing the intersect between a line and a plane with any robustness is impossible on modern computers with float or double. sometimes when you intersect meshes that have nearly coplanar faces, the intersection might shoot vertices near some infinity because of division inaccuracy.

Re: Show HN: 3D Vector Graphics

#13

Post by fogleman »

jasonwatkinspdx wrote: post #10
fogleman wrote: post #7

Earlier quoted context omitted.

Even cooler if I could figure out some general way of parameterizing & texturing the surface instead of just rendering the triangles. Any ideas?

Hughes Hoppe has done a variety of research that depends on finding interesting parameterizations of meshes. His papers aren't exactly lightweight on the math, but you may find some ideas there: http://research.microsoft.com/en-us/um/people/hoppe/ http://research.microsoft.com/en-us/um/people/hoppe/proj/vfd... http://research.microsoft.com/en-us/um/people/hoppe/proj/lap...

Awesome, thanks. I'll check that out.

Re: Show HN: 3D Vector Graphics

#14

Post by scrumper »

f2f wrote: post #12
scrumper wrote: post #9

This looks pretty great, I'll play with it. Can you explain this from the Readme? Unfortunately, it's difficult to compute the joint formed at the boundaries of these combined shapes, so sufficient texturing is needed on the original solids for a decent result. What is hard about computing the joint? Why does texturing help? My question is from a perspective of curious ignorance, not arrogance (i.e. me saying "don't…

unless you're dealing with sufficiently large integers computing the intersect between a line and a plane with any robustness is impossible on modern computers with float or double. sometimes when you intersect meshes that have nearly coplanar faces, the intersection might shoot vertices near some infinity because of division inaccuracy.

Yes that makes sense. Thanks.

Re: Show HN: 3D Vector Graphics

#15

Post by aardvark179 »

fogleman wrote: post #7
WhiteNoiz3 wrote: post #2

That's pretty cool. A commandline app that just takes an .OBJ file and renders it to an .SVG would actually be pretty useful (viewport position / orientation would of course need to be options as well).

Even cooler if I could figure out some general way of parameterizing & texturing the surface instead of just rendering the triangles. Any ideas?

I seem to remember there's some good stuff from Pixar on contouring which might be helpful.

http://graphics.pixar.com/library/Contours/paper.pdf

Re: Show HN: 3D Vector Graphics

#18

Post by nikolay »

jasonwatkinspdx wrote: post #10
fogleman wrote: post #7

Earlier quoted context omitted.

Even cooler if I could figure out some general way of parameterizing & texturing the surface instead of just rendering the triangles. Any ideas?

Hughes Hoppe has done a variety of research that depends on finding interesting parameterizations of meshes. His papers aren't exactly lightweight on the math, but you may find some ideas there: http://research.microsoft.com/en-us/um/people/hoppe/ http://research.microsoft.com/en-us/um/people/hoppe/proj/vfd... http://research.microsoft.com/en-us/um/people/hoppe/proj/lap...

Great! Hughes Hoppe's work is amazing!

Re: Show HN: 3D Vector Graphics

#19

Post by fogleman »

Patient0 wrote: post #17

Question: at the bottom of https://github.com/fogleman/ln/blob/master/ln/matrix.go Did you type that in manually? I wonder if there's a way to do that in Go that doesn't have as much duplication, but has the same performance?

Probably found the algorithm somewhere and used multiple selection in Sublime Text to quickly reformat it.
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