In this short grasshopper tutorial I want to show how you can use Point on Curve component. You can find it here: Curve > Analysis Or you can simply type the name of the component.

First let’s define a curve by 3 arbitrary points using Construct Point: Vector > Point

Set the X, Y and Z values and merge those points: Sets > Tree > Merge

Now we can have a curve using Interpolate component: Curve > Spline > Interpolate

Remember in order to have a smooth curve, curve degree should be 3

In the next step let’s say we have another arbitrary point and we want to draw a line between that point and our curve. Using Point on Curve component and Line Component: Line > Primitive will get us there.