Houdini Study Note (i)

The corresponding document is Houdini Help: Expression Cookbook Chapter Ripples

To get ripples radiating from a center, base the sine function on the distance of the-the-center of the surface:

Position Y

sin(sqrt(($BBX-0.5)^2+($BBZ-0.5)^2)*1080)

To animate this, add a time-based variable to the expression:

sin(sqrt(($BBX-0.5)^2+($BBZ-0.5)^2)*720+$F*4)

Point node position y:sin (sqrt (($BBX -0.5) ^2+ ($BBZ -0.5) ^2 *1080-$F) *0.4

Logarithmic Spiral

This creates a logarithmic spiral, reminiscent of nautilus shells.

Position X	cos ($PT * 2) * $PT / 200 - 0.2
Position Y	sin ($PT * 2) * $PT / 200 + 0.2

Houdini Study Note (i)