# Moving facade tutorial – Vronka

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Categories: Tutorials

Originally I was planning to use COR-TEN on my facade of my semestral project (why i used polycarbonate is a different story). While studying that material, I have noticed it can often be perforated for aesthetic and some practical reasons. So i figured out grasshopper could calculate the perforation for us. Then I realized the facade can go even further than that, and hide some mechanism behind theese perforated holes.

First i started with simple attractor,

for that i needed some points, and i made theese by series of construct point.

then for the attractor to work i needed to calculate vector to certain curve (which would be the attractor in the end)

then with remap i have made the attractor work – the radius of the circle is based on distance of the curve

in the end i just dispatched the smaller holes to filter them out (to get rid of some unrealistically small holes)

and that was it.

Then i thought i can make the facade react to some events. I made that by working with image sampler – so first i popped image sampler in and used picture of Jan Palach just as example, if the facade would be used as a memorial of the day of his death. But you can use any picture you want actually.

So the image sampler is not giving us any information so far. For him to do so I decided to “map it” to a rectangular grid

I used file path to deconstruct the picture into surface and find out what is the U and V parameter of the picture. So i could fit the size of the grid to the picture.

Then i divided U and V parameter to get the ratio of theese two parameters and multiplied that by any number i want. This number will work as our scale of the grid.

As we can see the image sampler is giving us numbers now! Its set to black and white channel, so the numbers are from 0 to 1 decided by the ammount of grey in that exact spot of the grid. Then by adding another rectangular grid we were able to assign circles to points of grid, and circle radius is determined by the ammount of grey the picture has in that exact point. I added multiplication for bigger control of the radius.

Then again i dispatched smaller geometry and the mapping was done! I can adjust the scale of the grid by the number slider i multiplied the U and V ratio by earlier.

Then i just thought about how the mechanism would work and found out that similiar system to apperture on a camera would be just fine! So i started to work on that by a circle with origin point and number slider for its radius.

I have then used evaluate curve to divide the circle into a number of points,

where I then constructed planes and rotated them how i needed.

Then i created the curve i wanted to use for the apperture, and that was a triangle – its the best solution in my opition, because you have overlapping sides and the edges make something similiar to circle. Then i needed to deconstruct the polyline i created to assign the tip of triangle i wanted.

Now theese triangles make a polygon. I just make surface out of them and that was it.

And now by adjusting the circle radius i can move the triangles.

Now my next step after some consulting was combining the above – apperture and image sampler. First i thought its not going to be such a problem, but when I tried it I bumped into some obstacles.

Anyway – I started combining the two codes, by putting the radius (data from the B&W photo) and the points of origin (data from the grid) into the apperture circle, however i had to graft the data coming from the circle to the “evaluate curve” for this to work! Otherwise i would’nt be able to work with multiple circles!

This is where the trouble began. I the apperture was made out of 7 small triangles, and if I put theese appertures together, unwanted holes started appearing, making the wole picture unreadable!

Instead of fixing this, I thought how the mechanism would work in real life – perforated corten behind which is some kind of apperture mechanism. So I decided to hide theese holes behing a rectagle with cut out circles. For that i first created the rectangle of the size i needed it to be, then attached the same grid onto it. Then by working with list – Sort list, etc. I have chose the biggest radius to be the radius of all the cut out circles.

Now by “surface split” I have made the needed surface – I just baked it and deleted all the circles. Then i reassigned it as a new surface for later work.

Then I’ve moved the surface abit upwards, added custom swach and it was done!

Unfortunately by my reckless working with so much geometry, I have seen this screen few times. It had led me to work more carefully.

But in the end, the result is pretty nice in my opinion. And the best part is – you can do this with any picture! Well.. Some might look better, some might look worse.

FILES :

grasshopper : vronka_tutorial_ghFILE
rhino : Vronka_tutorial
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