Maybe I'm just an idiot, but whenever this appears to happen to me, it was because I had the network view larger before and now have it smaller. When I dive into the objects, I see nothing and panic, but it's just because all of the nodes are far outside of the new visible region, so I have to hit Space+H to move the view.
If that isn't it, there may be a backup directory created by Houdini as well, with backup HIP files in it, so try looking around for that.
Hopefully you haven't lost any work!
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Houdini Lounge » projects saving surprise
- neil_math_comp
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Houdini Indie and Apprentice » vray for Houdini?
- neil_math_comp
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netfrag-sam
Raytracing and GI is from my perception something like 10 times faster.
Especially when doing interiors. I did this Houdini waterfall tutorial
where you just have the ground object and the waterfall.
Lit with just an environment light it took some minutes to get a decent
and clean result with Mantra. Especially with refractions I experienced
major slowdowns with Mantra (and I tried all the different modes with
different settings). You can render scenes like this within some
seconds in Vray.
Maybe I'm just over-extrapolating from my extremely limited experience, but I ran into a problem where with refractions and reflections, I had a very simple scene taking 45 minutes/frame to render, and it turned out the problem was that by default in the Mantra Shader Builder node, displacement was being done even if the displacement is not used. It's apparently soon to be fixed, but disconnecting the displacement shading nodes inside the Mantra Shader Builder node got my scene down to 1 minute/frame. It might be worth checking if that problem's happening.
I got another bit of speedup on that scene by switching from regular raytracing to PBR and tweaking the settings so that it looks the same but with many fewer rays.
Houdini Indie and Apprentice » Simple displacement noise question
- neil_math_comp
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It looks like the noise is about the same to me. Keep in mind that the displacement is in actual units, not relative to the size of anything, (else subdividing a surface would change the displacement), so if you make a grid with 20 times the side length and you move the camera back 20 times as far so that the grid looks the same size as before, the exact same amount of noise will appear 20 times smaller, since it's 20 times as far away. You'll have to increase the noise by a factor of 20 to have the noise be as prominent in camera space as it was when you were 20 times closer to the grid.
Edit: More specifically, (upon double-checking), the displacement is in object space, so another way you could do it, if you want the noise to increase with increasing object size, is to change the scale on the object node.
Edit: More specifically, (upon double-checking), the displacement is in object space, so another way you could do it, if you want the noise to increase with increasing object size, is to change the scale on the object node.
Technical Discussion » Linux on mac and houdini
- neil_math_comp
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If it has an Intel/AMD (x86_64) processor, Houdini should run fine. If it's an old PowerPC processor, I'm guessing not, unless you have a good virtualization program to simulate the x86_64 processor.
Houdini Indie and Apprentice » Simple displacement noise question
- neil_math_comp
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In the SHOP node for the shader, go to the Displacement tab and increase the Displacement Scale. If it's grayed out, click on the Enable Noise checkbox below. You might want to adjust the properties of the noise as well, but the overall scale is the Displacement Scale parameter. Hopefully this helps!
Houdini Indie and Apprentice » houdini for animated diagrams?
- neil_math_comp
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I've used Houdini to make fancy-looking versions of basic data plots, and I plan to do more of that sort of thing. It's a bit of a pain to do from scratch, but maybe I should make a set of assets and put them on Orbolt… when I get some spare time. :wink:
It'd be cool to make colour plots for 2D data or even volume visualizations of 3D data in Houdini, though those can get finnicky, depending on what you're trying to visualize. I suppose another visualization of 2D data is available via the IsoSurface SOP, where you specify a function on (x,y,z), and it generates a surface where the function equals zero.
It'd be cool to make colour plots for 2D data or even volume visualizations of 3D data in Houdini, though those can get finnicky, depending on what you're trying to visualize. I suppose another visualization of 2D data is available via the IsoSurface SOP, where you specify a function on (x,y,z), and it generates a surface where the function equals zero.
Technical Discussion » Particle Shape Morphing
- neil_math_comp
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Now that I look at it again, it'd probably be easier with the Sequence Blend SOP instead of the BlendShapes SOP if it's just that one sequence you want. You'll need to have the sphere's points in there twice (at the beginning and the end) and it's less flexible, but it'd save almost all of the mess with the expressions, which I probably got slightly wrong anyway, because I'm used to zero-based indexing instead of one-based indexing.
Technical Discussion » procedural cleanup degenerate primitives
- neil_math_comp
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I don't know if this is useful in your case, but if you want a way to group the degenerate triangles (and some other bad polygons), try a Measure SOP with the Area option to compute the polygon area, then group by expression $AREA==0. If you need a scale-invariant way to group the nearly-degenerate triangles, measure the area, measure the perimeter, then group by something like $PERIMETER*$PERIMETER>=1e4*$AREA.
Edit: Had 1e-4 instead of 1e4.
Edit: Had 1e-4 instead of 1e4.
Work in Progress » Ice Cream | Viscosity WIP
- neil_math_comp
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Houdini Lounge » how to have the wire not stretchy?
- neil_math_comp
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As paradoxical as this may sound, I think the wire might actually not be stretching, just bending. On the last image, the bottom of the bottom wire did move down, but the curve was also less wide. It could be that the total length of the wire didn't change, even locally, but that it simply bent into a different shape.
If there's an easy way to reduce bending (I haven't done anything with wire, so I don't know how; I think you're probably right with the angular spring constant thing), maybe try that and see what happens. I'm pretty sure there's a way to allow different amounts of bending at different parts of the wire if you still want to have the bending near the fixed point and not elsewhere. I just have no experience with wire.
If there's an easy way to reduce bending (I haven't done anything with wire, so I don't know how; I think you're probably right with the angular spring constant thing), maybe try that and see what happens. I'm pretty sure there's a way to allow different amounts of bending at different parts of the wire if you still want to have the bending near the fixed point and not elsewhere. I just have no experience with wire.
Technical Discussion » Curl Calculation
- neil_math_comp
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The curl of a vector field is just a vector field, not a matrix field. The second equation image on Wikipedia is probably what you're looking for. It defines curl directly in terms of derivatives, so there's no ambiguity about cross products: http://en.wikipedia.org/wiki/Curl_%28mathematics%29#Definition [en.wikipedia.org]
Hopefully this helps!
Hopefully this helps!
Work in Progress » grass & more ...
- neil_math_comp
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Also, it looks like instead of just displacing the divots in, it's (also?) displacing everything else out, so if there's a way to set that outer displacement as zero displacement, that might be more what you're looking for. Hopefully that helps! Oh, and you can turn edge coving back on to avoid cracks.
Work in Progress » grass & more ...
- neil_math_comp
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That looks a bit like edge coving gone wonky, which might occur if the two polygons are displaced away from each other. To check, try disabling edge coving on the object; if it's then black in the middle, that's what's happening, and it'd be useful if you could send a copy for testing. If that's the case, there's probably a constant offset on the displacement map, so that when it's wrapped, all polygons are pulled outward (in their normals' directions) in addition to the bumps, which probably isn't what you wanted. If it looks the same with edge coving disabled, I don't know what it is.
Houdini Indie and Apprentice » Bad side effect after bevel
- neil_math_comp
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What “this” are you referring to? Do you mean the unusual shading? If so, does it look that way in the Rendering tab, or just in the viewport? If it looks the same in the Rendering tab, there's probably something off about the geometry or normals. You can recompute normals with a Facet SOP if that's the case. If it only looks that way in the viewport, I wouldn't worry too much about it, since your final renders will be fine, though applying a Divide SOP with convexing and max edges set to 3 (triangulating the geometry) might make a difference.
Houdini Indie and Apprentice » A Fluid fundamental problem, please help me.
- neil_math_comp
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Are the equal points on the cup consolidated? If not, maybe try applying a Fuse SOP to consolidate the points that should really be the same on the cup. I don't know if that'll actually help, but I can see how not having points consolidated might lead to problems like that. (the penetration, that is, not the settling)
Houdini Lounge » delete point and edge without remove face?
- neil_math_comp
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Work in Progress » Filling polygonal model with rocks asset
- neil_math_comp
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Pretty neat idea! Is there a way to have different distributions of sizes/shapes of rocks? For shorelines with pebbles fading into sand, or even other types of ground debris (like wood chips), it'd be really nifty.
Technical Discussion » Particle Shape Morphing
- neil_math_comp
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Does the BlendShapes SOP do what you'd like? I tried putting down a sphere, a square, and a triangle separately in a single geometry object network, then applied a scatter SOP to each, then combined the three using a BlendShapes SOP with Blends set to 3 (for 3 shapes). Setting expressions for the blend values seems to let me blend between them over a sequence of frames. There's probably a much easier way to set up the expressions than what I did; I'm fairly new to Houdini, myself.
Houdini Indie and Apprentice » Alpha on geometry doesn't seem to work
- neil_math_comp
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When I was fiddling around with trying to get transparency working the other day, someone mentioned that the default shader (plastic) completely ignores transparency, so that might be the source of the problem. The Mantra Surface Shader seemed to have the options I was looking for with reflections and refractions. It had some options for it to look at point attributes too, though I can't remember exactly what they were (my Houdini's currently blocked on a sequence that's slow to render).
Houdini Indie and Apprentice » how to use python to get centroid xyz of a polygon
- neil_math_comp
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Keep in mind that for polygons other than triangles and parallelograms, that gets you the centroid if the mass is equally distributed among the vertices, not the centroid if the mass is equally distributed over the area, which is a lot harder to compute. Of course, for many purposes, it doesn't matter which you use; just thought I'd let ya know!
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