# Spline Creation

Hey =)

First time posting here, nice to meet you all!

Ive got a few questions about splines/curves

Any help would greatly be appreciated!

I need to use 3d curves for tracks that an object rides along.
So what im wondering is:

A) is there a way to create accurate sizes in blender, say I want to create a 45 degree curve with a radius of 10 feet.

B) is there a way to merge, say a 2D curve designed on axis, with one on another axis, to form a 3D curve? (ie. a Topo view, and a Plan view)

Some examples of what I need to create, are for instance:

There is a straight/level path, followed by a 10 degree curve going up over a radius of like 40 (your average rise of like a ridecar in an amusement park). And during this section, the curve also makes a 45 degree curve, left, then right on smaller radii.

I design Top and Plan views in Autocad, but being able todo a 3d curve, especially in blender would be excelent.

Thanks!
Kevin

The cursor would be important in the situation you are describing. To rotate something 45 degrees around a center point, select the center point and hit Shift+S > Cursor to Selection. Then on the toolbar for the 3D window is a drop down for the Rotation/Scaling Pivot point. Click that and select 3D Cursor. Then, while rotating, hold Ctrl to go in incraments of 5 degrees, or just type 45 and hit enter.

If I understand what you are asking in B), go to the Edit buttons (F9) with the curve selected and turn on 3D. Is that what you are looking for?

Hope this helps.

-Laurifer

Thank you for the help =)

Im not quite sure I understand the weighting/scale of the handles though.

How do I ensure that the curve that was created, is actually along a circles circumfrence? (I notice that though the points are physically along the circumfrence, the actual curve can bend too sharply, or not enough)

Thanks again!
Kevin

Setting point weights only works on NURBS and Surface NURBS.

You could add a Mesh Circle with the desired radius and plot your curve along that.

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This is close to what im trying to achieve. Is there any way to create an “ARC” in blender? the Mesh Spin tool does this, but im looking for the fine resolution you can get with a mathmatical curve.

If you can picture two 45 deg ARC’s back to back, creating an S shape
This would the view from the top.

Id like to beable to create that and then looking from the side (so all you see is a flat line) create an 10 deg ARC out of that going up.

So the end result would be snaking arcs going left and right, while curving upwards over the span of the 10 deg arc.

Thanks again!
Kevin

Add a NURBS Circle, select the bottom-center and bottom-left points and hit C. Delete the bottom-center point and select the bottom-right one. Ctrl-Leftclick one Blender Unit to the right, then again 1 BU to the right, then 1 BU up and another BU up. On my test the first half of the new curve was unevenly weighted in the new half of the curve so select the bottom-center point and drop the weight to .50.

In the buttons window click the “3D” button then hit Numpad 1 (or whatever (3 or 7) to get a side view. B (box-select) the points you want at a 10deg angle, hit R, 10, leftclick. Move them down with G, Z (Z-axis in my case) and hit the down-arrow till they get to where you want them.

If you want the path to tilt (camber) hit T and give each point the necessary rotation eg, T, 10.

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