Title: Rendering part of a plane Post by: Imagyx on August 29, 2017, 09:23:07 PM Hi.
I'm using the 4 functions from http://www.iquilezles.org/www/articles/distfunctions/distfunctions.htm When using "Intersection" with ""Sphere - signed - exact" and "Plane - signed - exact" I get only the part of the sphere intersecting the plane. But it doesn't work with "Box - signed - exact". I get nothing out of it. Why ? Box and Plane are visible and definitively intersecting, when rendering both. And the sphere with the same 'radius' as the cube works... :hmh: Thank you for any hint :) Title: Re: Rendering part of a plane Post by: claude on August 29, 2017, 10:10:39 PM works for me :hmh:
see attached... Title: Re: Rendering part of a plane Post by: Imagyx on September 06, 2017, 09:54:33 PM Isn't this part of a box, therefore 3-dimensional ? I just want a part of the plane, which is 2-dim...
Maybe I misunderstood something, because after doing some tests, it seems that with intersecting box and plane I get one of the two parts of the box, which is cut by the plane. And these tests also revealed, that it's the same with a sphere, I just didn't see it before by chance. Example picture here: Title: Re: Rendering part of a plane Post by: claude on September 07, 2017, 03:20:40 PM in the distance estimation, the "plane" is really a half-space, which is solid on one side.
the problem with truly 2D things in 3D distance-estimation is that they have 0 thickness, which means rendering algorithms can error by going straight through them or require adjusting fudge factors to make everything thicker. maybe you really want a double-sided plane with a small thickness, which could be made by intersecting two opposing parallel half-spaces that are close together (but not coincident). Title: Re: Rendering part of a plane Post by: Imagyx on September 09, 2017, 12:25:25 PM Thank you very much, claude :) Thickness is indeed needed for the DE to work and your suggestion to intersect two half-spaces works for me. I can make the Plane much thinner than it is in the video (see below) and project an image onto the plane which is why I even needed a plane and not a simple box where the image would be wrapped around. Have a nice weekend. With this I definitely have mine :dink: |