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guache

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About guache

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    Joseph
  1. I have a flat, 2D shape with a messy interior (crisscrossed lines etc) and I want to extract only its 2D outline or silhouette. The post below suggests that Triangulate 2D can do this. Which settings in Triangulate 2D do this? Also, if you have other ideas how to extract an outline from a "messy", flat 2D shape, please let me know. Convex hull node
  2. Curvesect intersection points

    Thanks, works great.
  3. I want to get intersection points between two sets of lines, but I can't get curvsect to do this, no matter which options I try. All lines are on the same plane. What am I doing wrong? curvesect2.hipnc
  4. I want to use an ortho-style photo as a correct size reference in a Houdini ortho view. The full width of the image represents 3 cm and I use 1 unit in Houdini as 1 cm (I can change the image's pixel resolution to whatever I want) As far as the size values for the background image, is there a formula that allows scaling the background image so that its width is 3 units wide in a Houdini ortho view? I can fiddle with the size values manually, but I'd prefer if there was a math formula that would get me there quickly and exactly.
  5. I use Houdini to design parts for 3D printing. The requirement for 3D printing is manifold geometry ("watertight" models, no single edges, no "T" connections between polys etc). I have a polygonal object, the result of many Boolean operations. From my, human view, it looks "watertight": it's a polygonal shell that encloses a definite region in space, with no holes. But my slicing software (Simplify3D) gives me "non-manifold" verdict, high-lighting in red many of the Boolean'd edges. Is there some way in Houdini (SOP or OTL) to cleanly rebuild a mesh from scratch (based on an existing mesh) and clean it up for 3D printing? For example, turn it into a point cloud, then I, as a human, could provide the software with clues where "inside" and "outside" is (e.g. by creating points and defining them as "inside" and "outside" the model. The SOP or OTL would then rebuild all polys in a way that creates a consistent, clean mesh. I tried the PolyDoctor SOP and turned most of its "Repair" options on, but it didn't do anything useful.
  6. Thanks for all the ideas. I just came up with a visual analogy for this type of a problem: imagine you have a gnarly tree trunk and you scan it with a laser scanner around its perimeter at a height of, say, 3 feet off the ground: you get a string-like, convoluted point cloud that "envelops" or "encloses" the trunk's cross-section at that level. The goal is to reconstruct the cross-section from the points, as a single, closed polyline. This example has the "no-overlaps" condition built-in, as a tree can't really grow "into itself", like an arbitrary curve can.
  7. Thanks, but Edge Transport won't work. When I said "string-like", I don't mean the points are connected, only that they form an outline of a shape (like a map of a country), as opposed to being a random splotch of points. In your hip, the edge connectivity already "solves" the problem. From what I see: there are 2 approaches: 1) signed angle around the centroid, 2) cylindrical uv coordinates. Another solution just came to mind, if the points are reasonably far from the centroid and evenly (more or less) spaced apart: a vex code, where you loop through all points and find a nearpoint for each, while excluding all already-found nearpoints. This would "trace" the outline by finding closest points CW or CCW. This approach could deal with cases like radial "overhangs" (i.e. protruding "peninsulas" that curve left or right etc), where an angle-based approach wouldn't work right.
  8. Thanks. If there are many threads about this, maybe SideFX should add it to the Sort SOP.
  9. I sometimes need to sort a bunch of points radially. The points lie on a single plane and form a string-like, closed, irregular shape, kind of like a map of a country. I created my own OTL which computes a signed angle between each point and the centroid of the figure, then sorts the points. It works fine, but I was wondering if there's a quick (i.e. just a few SOPs) way to to do this using standard Houdini SOPs.
  10. Thanks, that's exactly what I wanted. BTW, if someone has a way to solve this with volumes (i.e. merge the boxes into one object by converting to a volume, then back to polys), yet still preserve the simplicity (i.e. not create unnecessary polygons or uneven, "beveled" edges etc), I'd love to hear it.
  11. In Houdini, I have a 3D shape that consists of multiple boxes. What's the simplest way to join them into a single object defined ONLY by the absolutely necessary corners? In other words, I want to get rid of all unnecessary vertical and horizontal divisions on the otherwise flat surfaces. I'd prefer not to go through volumes etc, as I'd like to preserve the simplicity of the shape. Thanks.
  12. COPS memory leak

    I have a COPS setup of ~25 nodes. I'm trying to comp a sequence of about 10,000 frames and I see a memory leak. Every frame adds about 20MB to used RAM. Given the length of the sequence, I keep running out of RAM. Is there a way around it, e.g. some kind of a COPS node that frees up memory or some other workaround? In Compositing Settings, I've already lowered the max comp resolution to the minimum I need, and the bit depth to the acceptable minimum (8-bit) but the leak is still here. Win 7 x64, Houdini 16
  13. Thanks for the replies. I wonder if there's a way to apply "vcomment" to the virtual viewport camera so the HUD shows up even if there's no actual camera in the scene.
  14. In Houdini, is there a way to show some custom values as a HUD-type display in the screenspace of the viewport (any viewport, not necessarily cam viewports)? I mean something similar to the framerate display (Display Options->Guides->Additional Info->Show Time) but for custom values.
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