# Friction based vertex maps

 05 May 2013 brasco Polygone   portfolio Jon Bosley United Kingdom Friction based vertex maps Hi all, Anyone know of a solution for friction based vertex maps? Example: A car wheel spinning and building up temperature. I need it to be procedural, but also not just a linear increase in already mapped vertex weights (i.e. wheel revs increase = weight increase) but generated based on rotation speed and contact time with a surface. I appreciate this would most likely require a plugin or scripting of sorts, but if you have any clever solutions/ideas, I'd love to know. cheers brasc __________________ brasco on vimeo share quote
 05 May 2013 littledevil Meh   portfolio Ferdinand Germany the easiest solution would be : take your point object the vertex map is derived from and find for each vertex the shortest connection the collision object. range map this vector based on some min, max values into a float. multiply this float with the objects rotation velocity length and you have the heat value for that vertex. to be accurate you would have to do some closest point on surface calculations instead closest vertex, which can get pretty fast pretty slow in python. accessing dynamics (bullet solver) data is not possible in python and for all shader based solutions there is the problem that you cannot instantiate volumedata in python which does make it impossible to sample volumedata based shaders correctly outside of methods which provide this data. Last edited by littledevil : 05 May 2013 at 09:06 PM. share quote
 05 May 2013 brasco Polygone   portfolio Jon Bosley United Kingdom Thanks for the info Ferdinand, it get's me on the road to a solution! I'll experiment with that idea and see if I can apply it with my limited scripting knowledge. cheers brasc __________________ brasco on vimeo share quote
 05 May 2013 littledevil Meh   portfolio Ferdinand Germany hey, another solution i haven't thought of is a pretty fakey xpresso solution. you could create a falloff node covering your collision area. lets assume you have just a flat road. you would create linear falloff facing along the roads polygon normal. so the closer the object will get to the road the more it will be covered by the falloff. then sample for each vertex that fallof node multiply the data back and forth and you have something surprisingly convincing. i am here only at demo, so only screenshots. i added also a fallback at frame zero so that the vertexmap would be reset properly. you could also add a noise node to add some variation to heat map. the key part is getting the multiply nodes right. the cooling node math multiplier is 0.97 and the multiplier with only one port above the friction node is 0.025 in my example. the iteration, distance and condition ports nodes empty ports are all on its default value (0 or 0,0,0). general setup (you can see the yellow end of the linear fallof plane, the red plane is covered by the floor). http://i.imgur.com/55rS70u.gif xpresso setup: http://i.imgur.com/STQ8Ta0.gif happy rendering, ferdinand Last edited by littledevil : 05 May 2013 at 01:18 AM. share quote
 05 May 2013 brasco Polygone   portfolio Jon Bosley United Kingdom You've gone above and beyond there, thanks very much for sharing. I'm going to try both, the xpresso version looks more up to my level though so thanks for posting the setup! I'll report back when I get some good results. cheers brasc __________________ brasco on vimeo share quote
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