Smart Knot

Project Description:

This is a project I created because I wanted to try out making a modeling tool. So I figured out that ropes are quite time consuming to do by hand so I made a tool called Smart Knot.

 

Rope Creation

Smart Knot is a Houdini Engine tool I made to simplify rope modeling. You only have to create a curve with a start and an end point and the tool wires a rope around a mesh and ties a knot around itself.

Rope1.gif
 

Hang And Wrapping

You have full controll over how much the rope should hang, how many times it wires around a mesh and what direction it wires around it. You can also Insert a point in the middle of the curve to intersect the ropes hanging, and make it hang over some geometry inbetween.

RopeGravitationMM2.gif
 

Wrapping Logic

The wrapping of the rope is made with ray-casting from inside the object. It also gets the intersecting objects rotation by calculating the wrappings up vector by calculating a cross vector from the face’s longest edge.

RopeWrapping2.gif
 

Rope Thickness And PolyCount

You can controll the ropes thickness, the wrapping and the knot adapts to it. You can also controll how many divisions the different parts of the rope has.

RopeResolution3.gif
 

Rope High Poly and UV’s

A highpoly rope is created for baking out normals and AO for the rope. You have controll over the highpolys twisting, amount of weaves and amount of fibers. The ropes UV’s are based on the middle part of the rope because it will always need less detail than the knot part. Based on the middle rope the wrapping and the knot parts UV’s are stacking each uv shell in order to maintain a seamless texture on the rope.

RopeHighPoly.gif
 

Final Thoughts

I am happy how the project turned out and that i will never have to worry about modeling ropes again. I also felt that i learned a lot about vector math's during the project. If i would change something about the tool it would be adding more manual controll, everything is very automated but you might want to be able to add a manual offset to the knot and right now that is not possible. I also got feedback that you might want to do the ray casting for the wrapping from outside of the mesh but because the sizes of the geometry can differ so much that would not work so well for the set up i used.