perhaps (just perhaps) you can get there with the edit_UVs node - it does allow to rotate UVs. so maybe if you rotate the UVs first (based on particle rotation), and then give them the scaling and translation offset ? rotating afterwards sounds more tricky with the offset and all
-----Original Message----- From: olivier jeannel Sent: Tuesday, October 01, 2013 1:43 PM To: [email protected] Subject: Re: Particle "taking uvs" from it's emitter Just copying his rendertree and using the "my-Uvs" as Offset gives promising results. Now I just need something to correct my orientation : it's super in facing X axis particles, but mines need to have some oriention... Le 01/10/2013 13:11, [email protected] a écrit : > sprite node in the rendertree is just a way of doing tranparency (its > resetting the raycount on each incursion I think) - so you can get through > a > lot of transparent surfaces without increasing the raydepth. It has > nothing > helpful to offer to help with uv coordinates on particles. > > particles in softimage are points - and you can give them a single UV > value > easily enough - as discussed here that will just enable you to get the > proper color for the texture map. > certain shapes have uv coordinates built in - such as the sphere or > rectangle - which by default will map a single image on the entire > surface. > the obvious solution is to combine the single color from the underlying > texture with a transparency map on the particle to give them some shape > and > variation - it can give you the (flawed) appearance of tearing up a > surface > into pieces - (hint: besides the uv you can also use the normal at the > surface which will give you identical shading - very helpful!) - but its > not > gonna be a proper crop from the texture on the emitting surface. > > by calculating proper UV remap values you can crop a part of an image - so > technically your solution is there. (if you're fine with flat rectangular > particles that is) and the link you gave seems to have solved that. With > an > ordered grid with a rectangular mapping it shouldn’t be too hard to do. > 5x5 > grid - so each particle will have coords from 0-0.2 with offsets in > multiples of 0.2 in U and V - you get the idea. > > With an arbitrary polymesh surface, having an arbitrary UV set, likely > with > seams and arbitrarily sized particles, calculating those proper remap > values > is much more complex, and way above my head for sure. > In such a situation I'd rather got the route of fracturing the object, and > instancing the individual pieces to particles - but that is quite a > different proposition and you will hit performance problems with 100k > particles for sure. And there is Guillaume's addon to transform polygons > by > particles - which is very nice for performance - if the shape of > individual > polygons is ok for you. > > -----Original Message----- > From: olivier jeannel > Sent: Tuesday, October 01, 2013 12:18 PM > To: [email protected] > Subject: Re: Particle "taking uvs" from it's emitter > > Damn, that's annoying... > What about the Sprite node ? > SecondReality did something > https://vimeo.com/34463159 > But on a grid (my object is 3D with a lot of particles and overlaps) > > Le 01/10/2013 12:05, [email protected] a écrit : >> you're not missing something, this is totally normal. >> at any given position (location) you have a single UV coordinate (one u >> and >> one v value) - so that will result in a single color for the whole of the >> particle. >> >> in order to get the corresponding crop from the texture, you would need 4 >> uv >> coordinates for the four corners of a grid assuming your particle is a >> rectangle - but a particle is a single point so that’s just not going to >> work. (yes - you could save 4 attributes but you can't interpolate >> between >> them in the rendertree) >> I guess *in theory* it could be done, by calculating proper values to >> drive >> the UV remap in a texture node, for each particle based on it's position >> in >> the UV set and size - and saving those in a number of attributes - - but >> this is far from trivial. And you couldn’t account for seams in the map. >> >> >> -----Original Message----- >> From: olivier jeannel >> Sent: Tuesday, October 01, 2013 11:18 AM >> To: [email protected] >> Subject: Re: Particle "taking uvs" from it's emitter >> >> Sorry Grahame, but it's not working. I mean it just gives a a color to >> the particle, but not the piece of texture Uvs corresponding to its Emit >> Location. >> Here's a screengrab, I probably miss something : >> >> Le 30/09/2013 21:11, Grahame Fuller a écrit : >>> Plug Self.EmitLocation into the source port of a Get Data, then get >>> cls.Texture_Coordinates_AUTO.Texture_Projection.UVs. >>> >>> gray >> >> >> >> >> >> -------------------------- >> To unsubscribe: mail [email protected] with subject >> "unsubscribe" and reply to the confirmation email. >> >> -------------------------- >> To unsubscribe: mail [email protected] with subject >> "unsubscribe" and reply to the confirmation email. > -------------------------- > To unsubscribe: mail [email protected] with subject > "unsubscribe" and reply to the confirmation email. > > -------------------------- > To unsubscribe: mail [email protected] with subject > "unsubscribe" and reply to the confirmation email. -------------------------- To unsubscribe: mail [email protected] with subject "unsubscribe" and reply to the confirmation email. -------------------------- To unsubscribe: mail [email protected] with subject "unsubscribe" and reply to the confirmation email.
