Drawing and Editing Splines

Owned by thomas (Unlicensed)
Last updated: 21 Jul, 2015
4 min read

RealFlow can read → splines that have been saved in SVG format (“Scalable Vector Graphics”) - a XML-based file format. Furthermore, splines can also be drawn inside RealFlow directly. SVG splines are exported from popular illustration and image-processing applications. The spline-based tools and nodes are located here:

Spline shelf

Drawing Splines

When you choose “Spline” from the “Spline” shelf, an empty container is added and the → viewport is set to “Edit” mode. A yellow frame indicates this mode:

 

 

  • A new control point is created with Ctrl/Cmd + RMB. If you want to add Bezier tangents to the control point do not release the mouse, but drag it to control curvature.
  • If you do not drag the mouse after the creation of control point you will get a linear connection between the points. It is not possible to change a control point's type from linear to Bezier or vice versa.
  • New points will always be added after the spline's last point.
Remove Points
  • Select one more points (Shift-click).
  • Press Del.
Add Points
  • Press Ctrl/Cmd.
  • Move the mouse over the spline where the new points should be inserted – a circle appears.
  • Right-click to add the point.
  • New points are always added as Bezier points.
Interrupt and Resume Spline Creation

The creation of control points can be interrupted and resumed at any time with a click on

Spline node > Node Params > Options > EDIT

Close and Reverse Splines

Spline node > Node Params > Options > Closed | Reverse


Importing Splines

Splines are imported either as separate, editable scene elements or connected to a → “DSpline” daemon, an → “ESpline”, or Dyverso → "Spline" emitter directly. The entire process includes just a few steps. First, choose how to import the spline from the “Spline” shelf. Then, a new window appears. The entries are exactly the same for all import options:

 

 

  • Under “...” the SVG is opened.
  • With “Center at origin”, the spline's original position will be neglected and the node is place at [0, 0, 0].
  • When “Pivot at center” is active RealFlow will recalculate the spline's pivot.
  • “Parent to Null” creates a null object and adds it to the spline's → “Parent to” field. If the null is animated the spline will follow its motions.
  • If the SVG contains more than one spline it is a good idea to “Group” them.
  • “Combine” is used to connect multiple splines. When enabled RealFlow creates connections between the individual splines.
  • “Plane” lets you choose the spline's 2D orientation: “XY”, “YZ”, and “XZ”.
  • “Scale” changes the spline's size – the value acts as a multiplier.

 

Once the spline has been imported, it can be edited. To do this, please click on

  • Spline node > Node Params > Options > EDIT
  • For a detailed description of how to work with splines please take a look at the “Editing Splines” subchapter below.

Editing Splines

In order to make a spline editable (this also applies to → “ESpline", → “DSpline”, and Dyverso → "Spline" nodes), select the node and click on

  • Spline node > Node Params > Options > EDIT
  • or the pencil icon in the icon bar.
  • A yellow frame appears around the viewport (see first image above)

 

 

By default, the spline's intermediate points are added by RealFlow automatically with “Adaptive” method. To change this go to:

Spline node > Node Params > Options > Intermediate points type > Uniform

With this option you will get an even distribution of subdivision points, and their number is controlled with “@ points”. The more points, the smoother the curve. In “Adaptive” mode, the number of intermediate points is controlled with “@ angle”. Smaller values create more subdivision. With higher settings, the spline becomes more and more edgy.

The mentioned intermediate points are made visible with

Spline node > Node Params > Display > Show intermediate points

 

 

This panel provides many more options for enabling or disabling a spline's viewport elements:

 

Green: original spline | Orange: hull curve | Yellow: control point indices

 

Control points can only be moved, but not scaled or rotated. To reposition a point, press W and click on a control point or a tangent handle. You will see an axes cross: 

  • Drag one of the axis to perform a locked motion along the X, Y, or Z direction.
  • Drag one of the small coloured rectangles for a free motion.
  • When a tangent handle is positioned both tangents are affect. If you want to move the tangents individually please select the associated control point, and choose Spline node > Node Params > Options > CP handle smoothness > Broken
  • Multi-selections of control points and tangent handles are possible with Shift-click.
  • Spline nodes can only be deleted when the “EDIT” mode is off.