creating vectorial masks without geomerative?

General Discussion Other

artcodeem..

creating vectorial masks without geomerative?

in General Discussion • Other • 1 month ago

Hello all:

I want to make a very simple thing. Create a square and rotate it 45 degrees and then mask it with another square.. .

I don't want to do it using PImages or raster images in general; I want it to be purely vectorial (for PDF export not containing images), and only using rect()

How can I do this? I have seen a way to do it with the geomerative library but the result is broken when you magnify it.

The toxi library apparently has also something (SutherlandHodgemanClipper). Does processing include something natively to do this kind of tasks? In actionscript 3 was super easy to create advanced masks not only with bitmaps!

Couldn't find it here in the forum or in the processing documentation!

Thanks a lot

Replies(3)

asimes

Re: creating vectorial masks without geomerative?

1 month ago

Is it really important to do it by masking? It is a lot easier to just make the octagon if not. I wrote a polygon builder for someone else recently (second post of: http://forum.processing.org/topic/visual-creation-of-a-triangle-filled-circle#25080000002398131 ), if you set:

int numSides = 8; // Instead of 15 in the other post

It will make an octagon. It can be rotated so that the flat side is on the top / bottom as well.

You can do it by line-to-line intersection (like masking) without a library. You would find all of the intersection points between the two squares, sort them clockwise (or counter clockwise), and then make that a new shape.

artcodeem..

Re: creating vectorial masks without geomerative?

1 month ago

Many thanks Asimes!

Actually my question it's not specifically about creating an octhogon or any other n-vertices shape. Its related about dynamic masking. Thanks anyway for the library!

I read this:

You can do it by line-to-line intersection (like masking) without a library. You would find all of the intersection points between the two squares, sort them clockwise (or counter clockwise), and then make that a new shape.

How would I go about this? Do you have any examples?

Imagine I want the mask to be dynamically generated, something like the following image:

many thanks in advance!

asimes

Re: creating vectorial masks without geomerative?

1 month ago

The line-to-line intersection process I described does not generalize to any shape masking. It is possible that one of the shapes have a spiral or some other structure that cannot be sorted clockwise / counter clockwise.

The only way I know of to do what you want is to describe the shapes with an equation that describes their area. This is not trivial and I have never tried to do it for shapes that are not easier to describe (rectangles, circles, spheres, etc.). I would do a thorough look online for 2D versions of this. If not, the process I am describing is sometimes referred to as Boolean Operations on Geometry.