Curve Frame on Surface#

https://user-images.githubusercontent.com/14288520/210639554-d0a9be1f-e0ef-4c9f-b165-2f17dad71e20.png

Functionality#

Given a surface and a curve in the surface’s U/V space, this node calculates a reference frame of a curve for the given value of curve’s T parameter. The frame is calculated so that:

it’s X axis is pointing along surface’s normal;
it’s Z axis is pointing along curve’s tangent (in 3D space);
it’s Y axis is perpendicular to both X and Z.

This node allows one to place some object at the curve on the surface, while aligning it both with curve’s tangent and surface’s normal.

https://user-images.githubusercontent.com/14288520/210656324-3e8fdb9f-8654-491b-b305-cf512293a717.png

Inputs#

This node has the following inputs:

Surface. The surface to put the curve into. This input is mandatory.
UVCurve. The curve to calculate frame for. The curve is supposed to lie in XOY plane; X coordinate means U parameter of the surface, and Y coordinate means V parameter. This input is mandatory.
T. The value of curve’s T parameter. The default value is 0.5.

https://user-images.githubusercontent.com/14288520/210652754-f1802ae1-4cab-4761-80fc-eab7a03965b2.png

Parameters#

This node has the following parameter:

Join. If checked, then the node will output single (concatenated) list of matrices for all input curves. Otherwise, it will output separate list of matrices per each input curve. Checked by default.

https://user-images.githubusercontent.com/14288520/210657860-01c05782-4475-4d65-b6d0-3a22d2fe1bf3.png

Outputs#

This node has the following outputs:

Matrix. The matrix defining the frame for the curve at the specified value of T parameter. The location component of the matrix is the point of the curve.
Tangent. The direction of curve’s tangent vector at the specified value of T parameter.
Normal. The direction of curve’s main normal at the specified value of T parameter.
Binormal. The direction of curve’s binormal at the specified value of T parameter.

https://user-images.githubusercontent.com/14288520/210658893-6fb8a1e6-4913-4d04-8a3d-0d49ea85aa60.png

Examples of usage#

Let’s generate an ellipse by generating a sine wave in U/V space of cylindrical curve. Then we use “Curve Frame” node to place cubes along that ellipse:

https://user-images.githubusercontent.com/284644/89296471-d28d0480-d67b-11ea-9ac0-d6104821ea94.png

As you can see, the cubes are aligned with a plane where the ellipse lies, but they are not aligned with the cylinder surface. Now let’s use “Curve frame on surface” node instead: