Emmm… really?
To me it looks more like an implicit sphere is used to calculate the SDF rather than an implicit sphere being used directly in the solver itself.
If you have a look at this amazingly basic hip file, it seems pretty obvious to me that while the volume representation mode is set to explicit sphere, in reality the solver is running the poligonized SDF.
In the help it says:
Implicit Sphere -> Calculate the bounding sphere for the geometry, and create a volumetric representation that precisely fills that bounding sphere.
It doesn't say anything about using an optomised sphere description in the solver itself.
Am I wrong?
Also, in the RBD Solver itself the help for the culling method says:
In simulations with a large number of objects…..
Sphere means the objects will be treated as spheres and trivial intersection detection will be done with these spheres. This is fast, but with long skinny objects could cause false positives.
So the behaviour described here is what I'm interested in. Very very fast sphere RBDs. The help doesn't actually say how to achieve this though.
Louis
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Technical Discussion » DOPs: basic sphere SDF
- louis dunlevy
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Technical Discussion » DOPs: basic sphere SDF
- louis dunlevy
- 641 posts
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Hey!
Semi trivial RBD question here.
In all the examples I've looked at the collision geometry for a sphere RBD is a brickered up poly representation of a sphere. Surely this is a big overhead for something as basic as a sphere as well as being innacurate?
Cheers
Louis
Semi trivial RBD question here.
In all the examples I've looked at the collision geometry for a sphere RBD is a brickered up poly representation of a sphere. Surely this is a big overhead for something as basic as a sphere as well as being innacurate?
Cheers
Louis
Technical Discussion » texture stamping
- louis dunlevy
- 641 posts
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Sometimes in these cases you're better off using sprintf in your shader to assemble the texture string and just passing in a simple attribute on the geometry. This way you can pass through lightweight point attributes and the shader deals with the stricky string munging.
Cheers
Louis
Cheers
Louis
Technical Discussion » getting opacity depth info a la raylevel
- louis dunlevy
- 641 posts
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Hey that's better than a poke in the eye! Thank you!
I would be curious to know if you can get this info in VEX..
Cheers
Louis
I would be curious to know if you can get this info in VEX..
Cheers
Louis
Technical Discussion » Access uvs info from obj import
- louis dunlevy
- 641 posts
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Your uvs could well be coming out of XSI as a vertex attibute rather than point. Try MMB on the node to see it's class. If you want point uvs, use the Attribute Promote SOP to change it's class or put down a point SOP and turn on the field for the uvs which should also promote it.
Technical Discussion » getting opacity depth info a la raylevel
- louis dunlevy
- 641 posts
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Hey!
Can anyone remember how to do this little trick?
I'd like to find some way to limit the opacity depending on how many surfaces a primary camera ray has passed through in Mantra.
I'd like to say “if this is the second or third transparant surface let the opacity be 1”. The Ray Bounce Level Vop getraylevel() can tell me this when I raytrace but I can't figure out/remember how to do this with straight opacity.
Cheers
Louis
Can anyone remember how to do this little trick?
I'd like to find some way to limit the opacity depending on how many surfaces a primary camera ray has passed through in Mantra.
I'd like to say “if this is the second or third transparant surface let the opacity be 1”. The Ray Bounce Level Vop getraylevel() can tell me this when I raytrace but I can't figure out/remember how to do this with straight opacity.
Cheers
Louis
Technical Discussion » DOPs: Wire Object
- louis dunlevy
- 641 posts
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Hey!
Let me be a little more specific. I'm having a quick bash at trying to do a tail/springy antennae type effect with the Wire Solver.
The problem I'm having is trying to override it's rest angles. Not being big into converting a vector to a quarternion to make the rest angle attributes I've tried setting orient, up, out etc etc all to no great avail.
I would have thought that setting the wire object to “Use Animated Geometry” would have sorted this out but alas.
If you have a look at the file attached you should see what I mean. I've just constrained a few points that get animated and I want my wire orinentation to be driven by these points. Should be easy?
Cheers
Louis
Let me be a little more specific. I'm having a quick bash at trying to do a tail/springy antennae type effect with the Wire Solver.
The problem I'm having is trying to override it's rest angles. Not being big into converting a vector to a quarternion to make the rest angle attributes I've tried setting orient, up, out etc etc all to no great avail.
I would have thought that setting the wire object to “Use Animated Geometry” would have sorted this out but alas.
If you have a look at the file attached you should see what I mean. I've just constrained a few points that get animated and I want my wire orinentation to be driven by these points. Should be easy?
Cheers
Louis
Technical Discussion » DOPs: Wire Object
- louis dunlevy
- 641 posts
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Hey!
Little query here. In the Wire Object DOP the “Use Animated Geometry” flag….
“Causes the geometry for the object to be pulled from the chosen SOP at each timestep. The positions of the points will be used to set the initial wire state, but will be simulated after that. However, attributes from the animated geometry will be used.”
Cool. 8)
But the position is still set once at the creation frame and left alone after that. The only way I've found to just pull in the SOP animated geometry is to use an RBD Object with the same flag set. Works fine for animated constraints.
A tad confusing! :?:
Cheers
Louis
Little query here. In the Wire Object DOP the “Use Animated Geometry” flag….
“Causes the geometry for the object to be pulled from the chosen SOP at each timestep. The positions of the points will be used to set the initial wire state, but will be simulated after that. However, attributes from the animated geometry will be used.”
Cool. 8)
But the position is still set once at the creation frame and left alone after that. The only way I've found to just pull in the SOP animated geometry is to use an RBD Object with the same flag set. Works fine for animated constraints.
A tad confusing! :?:
Cheers
Louis
Technical Discussion » Scatter SOP alternative attribute
- louis dunlevy
- 641 posts
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Technical Discussion » Scatter SOP alternative attribute
- louis dunlevy
- 641 posts
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seems bust to me!
If you use a custom attribute (say the primitive area from frame one of your animation) the distribution is VERY different than letting the Scatter SOP calculate the area distribution by itself.
Cheers
Louis
If you use a custom attribute (say the primitive area from frame one of your animation) the distribution is VERY different than letting the Scatter SOP calculate the area distribution by itself.
Cheers
Louis
Technical Discussion » SEV2 Raytracing displaced particle sphere primitives
- louis dunlevy
- 641 posts
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Cheers!
Were you able to reproduce it?
I'm just thinking about a workaround. I could instance an object with a sphere SOP in it (obvious) I guess. I'm just wondering if there's something more fundamantal going on..
:?
Were you able to reproduce it?
I'm just thinking about a workaround. I could instance an object with a sphere SOP in it (obvious) I guess. I'm just wondering if there's something more fundamantal going on..
:?
Technical Discussion » SEV2 Raytracing displaced particle sphere primitives
- louis dunlevy
- 641 posts
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Hey!
I came accross what can only be a bug IMHO..
I have a bunch of particles which I'm rendering as spheres in Mantra by simply setting pscale. V fast
I'm also displacing them a little which all works fine. Trouble is when I try to raytrace them (refraction using refractedLight). Think of looking at frogspawn through a goldfish bowl.
Without displacement the spheres show up through the refracting surface, as soon as they have a displacement shader (even if the displacement is set to zero) they disappear from the refraction..
A bug methinks?
Louis
I came accross what can only be a bug IMHO..
I have a bunch of particles which I'm rendering as spheres in Mantra by simply setting pscale. V fast
I'm also displacing them a little which all works fine. Trouble is when I try to raytrace them (refraction using refractedLight). Think of looking at frogspawn through a goldfish bowl.
Without displacement the spheres show up through the refracting surface, as soon as they have a displacement shader (even if the displacement is set to zero) they disappear from the refraction..
A bug methinks?
Louis
Technical Discussion » BUG: RSL VOP Network Crash
- louis dunlevy
- 641 posts
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We've had similar nastiness in 8.0.403.
Wierdly, certain VOPs have started setting vector4 inputs as default (seen in Max and Mult) and sporadically break (especially in a big network). The Null VOP completely breaks networks tto.
Actually, we saw that a Parameter or a Constant vector4 VOP would in itself produce bad code without a value.
Personally, I think VOPs need a bit tidying up and more functionality in RSL VOPs.
Louis
PS, what's the plan for dealing with dependancies when you get multiple copies of a VOP network?
PPS, a VOP palette (like the shader palette) would be nice! :wink:
Wierdly, certain VOPs have started setting vector4 inputs as default (seen in Max and Mult) and sporadically break (especially in a big network). The Null VOP completely breaks networks tto.
Actually, we saw that a Parameter or a Constant vector4 VOP would in itself produce bad code without a value.
Personally, I think VOPs need a bit tidying up and more functionality in RSL VOPs.
Louis
PS, what's the plan for dealing with dependancies when you get multiple copies of a VOP network?
PPS, a VOP palette (like the shader palette) would be nice! :wink:
Technical Discussion » A warper in COPs
- louis dunlevy
- 641 posts
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Bit of a thread on the mailing list about getting a warper (& a tracker) in COPs..
I once had a quick bash with the standard tools but I didn't quite get there. What I was missing was an easy way to get the difference between a source and a destination shape and render that position change as a colour in the source position with a pretty falloff. That's where I think the HDK would come in. Maybe pointclouds? Hmmm.. it would certainly help doing a falloff but it means going into geometry where you really want to stay in COPs for speed.
Have a look at the file attached. Just a dodgy hack :wink:
Louis
I once had a quick bash with the standard tools but I didn't quite get there. What I was missing was an easy way to get the difference between a source and a destination shape and render that position change as a colour in the source position with a pretty falloff. That's where I think the HDK would come in. Maybe pointclouds? Hmmm.. it would certainly help doing a falloff but it means going into geometry where you really want to stay in COPs for speed.
Have a look at the file attached. Just a dodgy hack :wink:
Louis
Technical Discussion » Procedural squid legs in a particle system
- louis dunlevy
- 641 posts
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Technical Discussion » Procedural squid legs in a particle system
- louis dunlevy
- 641 posts
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From what I gather you should download the very latest version to reap the benefits of some improvements in DOPs that could apply to this.
:wink:
Louis
:wink:
Louis
Technical Discussion » RBD without volumes
- louis dunlevy
- 641 posts
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Technical Discussion » RBD without volumes
- louis dunlevy
- 641 posts
- Offline
Now I am confused!
That example of your just works Hmmm… even though the “Use Volume Based Collision Detection” is on. Hey, it works though which is excellent. I just have to figure out why mine didn't.
L
That example of your just works Hmmm… even though the “Use Volume Based Collision Detection” is on. Hey, it works though which is excellent. I just have to figure out why mine didn't.
L
Technical Discussion » Rating topics on the Forum
- louis dunlevy
- 641 posts
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'fraid I'm in the lower echelons of the geek fiefdom when it comes to that! Definitely worth persueing though.
What about the option of getting users to put a category on a thread when they start one? A little menu with DOPs CHOPs FOPs BLOPs etc.. ?
Beers
L
:wink:
What about the option of getting users to put a category on a thread when they start one? A little menu with DOPs CHOPs FOPs BLOPs etc.. ?
Beers
L
:wink:
Technical Discussion » DOPS Details view RFE
- louis dunlevy
- 641 posts
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I find Object properties such as Density hard to find in the Details view. To my surprise I found some stuff under the Postion header rather than Physical. Maybe there's some docs on the Details view in DOPs that I should be looking at?
Or some thread on the Forum that should have a rating of 5 million.. :wink:
Cheers
Louis
Or some thread on the Forum that should have a rating of 5 million.. :wink:
Cheers
Louis
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