# Maintain flat surface tweens in pufferfish

Hi

I am a beginner in Grasshopper and I am currently working with the tweening of surfaces in the pufferfish plugin.

I wonder if there is a way to have both equalized and flat tweened surfaces.

Here I have tried equalized tween through surfaces, tweened consecutive surfaces and tween 2 surfaces. When tweening through consecutive surfaces, the surfaces seem to maintain their flatness except when rotating around the x or y axis, but I can’t find a way to equalize them, however, when using tween through surfaces with the equalize option, the surfaces tend to bend.

Is there a way to tween multiple surfaces, maintain their flatness and have them equalized?

Best regards

Philip

Always attach files, always.

In short the simple answer is, not really, but maybe. In your first image of course it wont be flat as your input surfaces are not planar with each other. Tween consecutive wont help you here really as it is not something that evaluates the whole, it evaluates paired relationships. Equalized of tween through surfaces is an equalization along the tween path. You could use Tween Two Surfaces and shifted lists and measure some distance between each surface to determine how many tweens to make between to get something equalish and planar but the spacing of your input surfaces may not warrant truly equal spacing depending on if the goal is to land on the input surfaces.

Hi Michael, thanks for the clarification and quick reply, yes, i have figured that tween Two Surfaces multiple times is probably the best way, and to make the height difference as similar as possible by measurement, the end goal is to laser cut the samples, so I will probably go ahead with this method.

I have attached the files if you still want to have a look.

shapes_2.1.3dm (157.0 KB) shapes_2.1.gh (9.8 KB)

This will get you pretty close but things will be slightly off in distance because it depends what you are measuring from. In this case I measure from surface centers, you can imagine it would vary slightly if you used surface edges etc. The results are planar.

Tween Equal Planar.gh (17.0 KB)

and if it is vertical spacing you are interested in then this would be the way to go.

Tween Equal Planar Vertical.gh (17.7 KB)

Thank you very much, I will study this and get back!