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julian johnson

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julian johnson last won the day on May 19

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  1. Hi K'n'K, glad you liked it. I'm in the middle of a job at the moment so I can only give you brief pointers. You are right, though, I think it can all be done in the distance travelled CHOP. For reverse you need to establish some concept of what constitutes forwards and what constitutes reverse. I think using the tangents of the path curve and bringing them into CHOPs would be the way to do that - then compare the slope vector with the tangent vector. A dot product between the two would give less than 0 for reverse and greater than zero for forwards. Then just multiply the result of the area chop (length) by -1 to negate if you want to reverse (using the dot product to tell you whether you need to). For wheelspin I think a simple animated add to the length chop would do (for a manual spin) or using the acceleration to procedurally increase the length if it goes over a certain threshold. CHOPs are fiddly so it might take a few tries to get it right!
  2. It's been a while (!) but here's an interim development of the original double wishbone chassis concept. Now you can fully adjust chassis to match car - it's all done via names - so you can transform the model in any way you like (just don't change the point numbering as constraint naming is based on point numbers). Effectively bullet is used to make the constraints easy and the only real simulation is on the wishbone springs. Wheels are pre-animated along a path and then adjusted for roll, ackerman steering angle (inner and outer wheels at different angles). Still quite tricky to adjust the sim because mass, spring strength/damping, load transfer and conetwist maximum angles are all interrelated - change one and you need to change all the others! This test Porsche is overly springy to illustrate the basic concepts at work especially the load transfer forward to back. Needs more work on rest to action transition period, too! To change the car simply bring the new car and wheels into the chassis node and swap out, make sure to transform chassis geo to fit. Change path, collision ground as you see fit.... car_rig_bullet_julian.hip
  3. PolyBridge in For-Each Loop

    Does this do it with PolyBridge? No for loop required... MOD_Hex_Offset_01_bridge.hipnc
  4. This is a very rough hack of your straight setup but might give some ideas - you'd have to set your own scheme for how to create the curved paths and where to generate the offshoots...in this example it's very rudimentary. Intersecting_Lines_with_curl.hipnc
  5. Vellum hair - custom attribute for bendstiffness

    Not quite sure what effect you're going for, so I may be completely minsunderstanding your setup but it looks like i) your limpHair attribute was a point attribute which really needed to be on the constraint primitives and ii) your Sop Solver was not acting on the Constraint Geometry (and also not really transferring the limpHair attribute over to stiffness. I've changed all of that so at least you get a 'reaction' to your growing @wet attribute. As I said, may not be what you were after.. FurSetups_v003.hipnc
  6. Neighbour count doesn't seem(?) to work?

    Make sure in your countneighbours vop you plug in OpInput1 into filename like this:
  7. Project points on geo

    Added projection from the top...lidar_test_intersect2.hipnc
  8. Project points on geo

    I wonder if intersect_all() would give you what you need.. lidar_test_intersect.hipnc
  9. question for pcopne() function

    In your current scenario I think each point in your grid is doing a pointcloud lookup on the single point in input 2 and if it is in the radius will always only find 1 point. I think you need something like this which only does the point cloud lookup once in detail mode. Scott82N_detail.hipnc
  10. This will split at the length along the curve you specify with a given doorway width. I think you could easily refactor to use percentage of length... splitbylength.hip
  11. RBD material fracture wood - break soft constraint?

    I think the shelf tool is fine - you can put the constraint network above the rigid body solver if you want. The error you get, I am guessing, is because you need to turn 'Attach Internal Constraints to Object' on the Constraint Network node to 'Off'. Having read the help on that option at least 50x I still have no idea why or what it means in practice but it does work if you turn it off :-) glue to soft above.hipnc
  12. RBD material fracture wood - break soft constraint?

    Here's one way - a solver on the constraint geometry to remove each soft prim constraint based on either distance, impact, force, torque etc. (In this case distance). glue to soft.hipnc
  13. UV to mesh with matching prim area

    @P *= sqrt(scaleFactor); I think if you double the scale of something you quadruple its area... Edit. As Tomas just said!
  14. 'Dart throwing' algorithm

    I think this is as simple (and naive!) as multi-radius dart throw gets. No space partioning, no optimisations. Simple raw dart throwing. The image below took 2 minutes to cook. There are much better ways via relaxation, rigid bodies, circle packing etc. Many of them are on this site I think. dt.hipnc
  15. Updating RBD constraints from deforming geometry

    Using the fact that you can only really rotate one of the anchors per constraint polyline here's the pighead with just hard constraints rotated to look at the world space anchor. Can't quite work out how to get the initial orientations to flow through to the start of the sim yet. anchors and orientations_odforce4.hipnc