Using brushes for shadings.

[badnames]

Tasks

Ideally we would like to generate shadings in the shade layer using some sort of brush tool.

Possible approaches:

• Use a 2D variation of the marching Cubes Algorithm to generate a polygon from image data (https://medium.com/generation-of-computational-meshes-from-segmented/generation-of-computational-meshes-from-segmented-ct-scan-data-using-a-finite-element-technique-7bd8136bc1b4).
• Rewrite the backend such that it uses free form shapes or pixel image data instead of simple polygons.
• ...

Use case

Shade Layer

Related Pull request

1135

[markus2330]

@badnames thx for writing the issue. To know about this issue before we started heat map/shadings backend would have been worth gold :wink:

Rewrite the backend such that it uses free form shapes or pixel image data instead of simple polygons.

@danielsteinkogler Will this maybe be needed also for Drawing Layer? (Of course in case of shadings it is more complicated because of the heat map.)

[danielsteinkogler]

i think for drawing layer its not that relevant. At least for the frontend its not interesting how the data is stored. So i think the backend devs can decide how its most effeicient to store the shapes.

[markus2330]

We should avoid storing brushes differently in the DB, independent if they are semantically used or not.

[markus2330]

I currently think the best way is to build up the polygons with "brushing" is in the frontend by:

• union of a polygon of:
  • an existing, selected polygon from where the cursor started moving and
  • the space around a just drawn free-hand line (with a given "brush thickness")
• difference of other polygons

So if we do go that way, we need:

• operations in the backend for union and difference of polygons
• some frontend polygon library to not reinvent the wheel? Or does konvajs already provide enough?

Let us discuss it today to slowly come to a decision.