Outline of mesh (shadow)

I have a bunch of blocks (windows) and a surface (wall). I want to calculate the projected area of each window, and find the midpoint of each of the 4 outlining lines.

My idea for achieving this has been to use the “mesh shadow” function. However i have some problems converting the blocks.
I have tried to convert the blocks to meshes (explode + join in Rhino) however this does not seem to work. is there a better way to utilize a block? if not how can i convert a block to something usefull?

you only need to use the transparent planes in the window.

post the gh file of what you’ve tried so far

I would strongly advise to simplify the whole puzzle (you can do it with Instances … but is a bit complex [assuming that the instance is defined properly in order to locate the transparent items blah, blah]).

So … see what the attached does (also an over simplified thingy) and try to mimic it via GH native components.

Buildings_WinFrameProjections_V1.gh (30.9 KB)

I dont think i managed to explain my question properly based on your response.

I have windows (blocks) i want to find the total area of each window (red square) and the midpoint of the outlining rectangle (green points).

Well … that’s an elementary BIM puzzle: I mean that in a proper AEC BIM app (like AECOSim and the likes) objects (say doors, windows etc) are placed in others (say walls) via a more or less auto cut procedure … meaning that gross openings in your walls should be available … meaning the obvious.

That said R/GH are NOT a BIM thing nor they would ever been.

Other than that you have the “walls” on hand, right? So instead of inquiring the Instance Definition (the object “cookie cutter”) plus the Trans Matrix (*) applied to a given Instance Refrerence (the object that you have placed in the RhinoDoc) … just deal with the gross openings on walls (like in my entry level example) . That’s not 100% accurate (because the frames are not taken into account) … but you can bypass that via various ways.

(*) like in this simple C# piece of code:

That said in an AEC BIM app a “window” it’s a complex item where meta data always describe the solids present.

Thank you. I dont think i understood what you are trying to explain. I am not very familiar with computer programing, BIM and Rhino/GH. Could you please try to explain it in a more simple way? :sweat_smile:

Rhino/GH are the Rhinoceros and the Grasshopper apps.

BIM : Building Information Modeling > the new kid (20 years old - give or take) in the block for AEC (Architectural Engineering Construction) matters. Modeling in a BIM authoring tool connects the 3d model(s) and documentation(s) together.


  1. Targets a consolidated “core” (say a collection of 3d Models) that is the source for extractions (i.e. prehistoric plans, elevations, sections, master details and details) … and controls marker references from any to any (for any: read drawing or documentation/spec/etc).

  2. Defines various smart composite objects (sampled in named collections or better controlled via a proper RDBMS) and then uses various object “auto” placement Methods/ways (like a window to a wall) based on some sort of rules related with the Types of the 2 involved objects.

  3. Assigns meta data (tech descriptions, specs, prices … blah, blah) to any 3d object is used. These follow strict classifications into Articles (classes of construction works) and include various other informations usually derived from some RDBMS (I use ProjectWise by Bentley Systems - Google that) .

  4. Allows “easy” on the fly cost pre-estimations based on strict rules related with the objects defined and used. For instance if the object is of Type Floor YYY measure Area OR if is of Type InSituConcrete measure Volume Or if is of Type Door XXX get the unit cost etc etc

  5. Allows “easy” remote control of the construction (well … at least in theory) since more and more these days drawings and the likes are replaced with a bounch of on-site computers (and drones).

  6. Allows any query imaginable across the sum of Projects (on Local [Practice] or Global level [State/Country]) done that way: for instance find the most common type of alu extrutions used in towers done between 2015-2023 Or find all the Master Details related with a given raised floor OR rate the reliability of envelopes/systems used in stadiums OR evaluate the sustainable systems used for housing Projects … etc etc.

So the trend is clear: forget drawings and/or 3d Models and/or any papers … think a collection of “nested” e-informations that co relate actual 3d items (or compositions of items) and any information imaginable across the life span of the Project. MCAD apps call that PLM (Project Lifecycle Management).

Moral: Forget inspirations/big ideas/etc … now all what matters is data mining.

Hei Sofie -

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