Sun-path diagram and shading mask

Hi! How do you project the shading mask of a point and/or a surface on a stereographic sun-path diagram? (such as the ecotect images below- the left is from a point, the right, from a surface).

Thank you!

Hi Helena,

There are two WIP components that let you draw shadow masks and combine them with a sunpath. The results is in 3D but you can project it to XY_Plane. I attached an example file. (370 KB)

Love having it in 3D! Again, thanks for the great plug-in. I’ve also combined it with the watch the sky imagery (sky dome radiation) in photoshop, and wish that could be done in 3D. Mostapha?

Hi Mostapha,

Thank you for your answer, how do you adjust the time of the year for the shadow study. Using the grasshopper file you sent me, I put sliders in the sun-path component, but the shadows are not changing (file attached). (370 KB)


The shadow mask is not supposed to change when you change the date. You need to move the base point for that … or i understood wrong your question?



This is a bit of a reiteration of Abraham’s comment but the usual way that I have used the sky mask is to see that, if the sun falls within the shadow mask (in top view), you know that the sun is being blocked for that sun position. So the mask is meant to stay static while the sun moves.


Got it, thank you Abraham and Chris!

Is it possible to color the shadow from different “obstructions” according to the obstruction’s color?

Yes you can! Just keep in mind that the component is WIP and sometimes it may fail generating the curves. Here is an example: (370 KB)

Thanks Mostapha!

Great feature. Managed to get it to work for OnGround but doing odd things for SkyDome. (366 KB)

Hi Chris, The component is under development and there is good chance that it fails for complicated geometries but your case is pretty straight forward. Can you tell me what’s exactly the issue in your case? Is it that you don’t get the mask for one of geometries?

Mostapha, maskedSrfOnGround works fine for the simple case of two boxes but when I change to maskedSkyDome no mask appears. maskedCrvsOnSky does show in mask although colours are incorrect. See attached. Thanks for taking a look at this. (366 KB)

Hi Chris, You’re right. The component needs some real work to be useful. In general Rhino’s split functions can easily fail. In this case the script generates some invalid breps. Moving the point upward solves some of the issue but not all of them. See the attached. (370 KB)