Anti-matter booleans - Polyloop

julvr · 30th December 2006, 00:02

I heard someone in a post refer to render-time booleans as anti-matter booleans. I am not sure if this is his invention, or the industry term, but in any case, I was wondering if there is any plan for them to exist in Carrara.

Basically, the idea is you have an invisible object that makes holes in one or more objects it intersects with. It would be useful for example if you had a boat and wanted to make the water invisible inside of the boat. It also allows for animated holes in objects etc.

To me it seems like a fairly simple feature to implement in a raytracer -- basically if you are tracing a ray:

1) if the ray hits the target object first, the ray intersects the target object at that point
2) if the ray hits the front-face of the antimatter object, then it hits the target object (before it hits a backface of the antimatter object), then:
a) if the target object is a plane or non-filled object, there is no intersection.
b) if the target object is a solid, and the ray hits a backface of the target object before it hits the backface of the antimatter object, there is no intersection
c) if the target object is a solid, and the ray hits a backface of the antimatter object before it hits the backface of the target object, then the intersection is at the backface of the antimatter object...

Indirect lighting might be a bit tricky, but could likely be solved by creating a temporary polygon boolean right before rendering, and use those values for lighting.

Anyways, I think this would be very useful for modelling a lot of things (One example is creating windows in a house -- you could make all walls your target object, and then you could easily change the location of windows, duplicate them, etc).

bwtr · 30th December 2006, 02:51

I like the part about water inside a boat--which came up recently.

Suggest you email your thoughts to Eric at Digitalcarvers. He may allready be partway down the track for something similar--you never know!

Nichod · 30th December 2006, 18:55

I was the one (I believe) who mentioned the term. Its a common term. Though hardly an industry term. It comes from my Strata days. And its just another name for 'Rendertime Booleans'.

I do know that Eric might be part of the way there with his intersection plugin. But I do think this might be beyond the scope of a plugin. I'll direct Eric to this thread.

ewinemiller · 30th December 2006, 21:42

I am working on an update to Intersect shader that (if it works out) will solve the water in the rowboat problem. It will not be ray traced booleans. The work is mostly done, but I'm still working through a few of the special cases.

Ray traced booleans are on my short list of things to look at as sort of a next step to the Intersect shader.

Regards,

Nichod · 30th December 2006, 21:51

Quote:

Originally Posted by ewinemiller

I am working on an update to Intersect shader that (if it works out) will solve the water in the rowboat problem. It will not be ray traced booleans. The work is mostly done, but I'm still working through a few of the special cases.

Ray traced booleans are on my short list of things to look at as sort of a next step to the Intersect shader.

Regards,

Great to hear!

30th December 2006, 00:02	#1 (permalink)
julvr Vertex Join Date: Nov 2006 Posts: 25	Anti-matter booleans I heard someone in a post refer to render-time booleans as anti-matter booleans. I am not sure if this is his invention, or the industry term, but in any case, I was wondering if there is any plan for them to exist in Carrara. Basically, the idea is you have an invisible object that makes holes in one or more objects it intersects with. It would be useful for example if you had a boat and wanted to make the water invisible inside of the boat. It also allows for animated holes in objects etc. To me it seems like a fairly simple feature to implement in a raytracer -- basically if you are tracing a ray: 1) if the ray hits the target object first, the ray intersects the target object at that point 2) if the ray hits the front-face of the antimatter object, then it hits the target object (before it hits a backface of the antimatter object), then: a) if the target object is a plane or non-filled object, there is no intersection. b) if the target object is a solid, and the ray hits a backface of the target object before it hits the backface of the antimatter object, there is no intersection c) if the target object is a solid, and the ray hits a backface of the antimatter object before it hits the backface of the target object, then the intersection is at the backface of the antimatter object... Indirect lighting might be a bit tricky, but could likely be solved by creating a temporary polygon boolean right before rendering, and use those values for lighting. Anyways, I think this would be very useful for modelling a lot of things (One example is creating windows in a house -- you could make all walls your target object, and then you could easily change the location of windows, duplicate them, etc).

30th December 2006, 18:55	#3 (permalink)
Nichod Moderator Join Date: Apr 2005 Posts: 612	I was the one (I believe) who mentioned the term. Its a common term. Though hardly an industry term. It comes from my Strata days. And its just another name for 'Rendertime Booleans'. I do know that Eric might be part of the way there with his intersection plugin. But I do think this might be beyond the scope of a plugin. I'll direct Eric to this thread. __________________ Email Me. Visit my blog! Get hundreds of shader presets! Get Art of Shaders! And a preview for Art of Skin is now available. AMD Turion(TM) 64 ML-40 (2.2GHz/1MB L2 Cache) 1280 MB DDR 333mHz RAM 128MB ATI RADEON(R) XPRESS 200M w/Hypermemory(TM) 60 GB 4200 RPM Hard Drive DVD+/-RW/R & CD-RW Combo w/Double Layer Support 15.4" WXGA BrightView Widescreen (1280x800) I use.

30th December 2006, 21:42	#4 (permalink)
ewinemiller Cube Join Date: Jul 2005 Posts: 76	I am working on an update to Intersect shader that (if it works out) will solve the water in the rowboat problem. It will not be ray traced booleans. The work is mostly done, but I'm still working through a few of the special cases. Ray traced booleans are on my short list of things to look at as sort of a next step to the Intersect shader. Regards, __________________ Eric Winemiller Digital Carvers Guild Plug-ins for Carrara http://digitalcarversguild.com

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30th December 2006, 02:51	#2 (permalink)
bwtr Brian Join Date: Jul 2005 Location: South Australia Posts: 2,094	I like the part about water inside a boat--which came up recently. Suggest you email your thoughts to Eric at Digitalcarvers. He may allready be partway down the track for something similar--you never know!