exporting 2D plans & elevations - how best to go about this

[babbleon]

Hello,

At some point soon I would like to be able to create 2D views of my scene as viewed from an orthographic camera which I will then output as a vector line drawing in, say, DXF using maker.js or as a PDF using some library or other.

Generally, can anyone suggest how best to go about this please - I just cannot think of where to start.

For anyone familiar with CAD, this is like Make2D in Rhino or FLATSHOT in AutoCAD.

I guess this is computationally expensive as Rhino can take a while to do this, but that generates from NURBs, not meshes.

Hope this isn't too vague a question.

Thank you.

[Sebavan]

The hardest part would be to find a lib to do the vectorization process that could convert from picture (one frame rendered of the scene) to a vector data used by projects like maker.js.

[babbleon]

Thank you @Sebavan - I was thinking of extracting each individual visible vertex of a mesh and using that somehow.

I could render as lines, then get the server to run Potrace  to vectorise it, but I will lose accuracy and so this is not really an option. It needs to be millimetre perfect.

I will have a think.

[babbleon]

So, if I start from the basics.. is there a way to check if one particular vertex of a mesh is visible from a camera?

[babbleon]

three.js has an svg renderer: https://github.com/mrdoob/three.js/blob/master/examples/js/renderers/SVGRenderer.js & https://threejs.org/examples/#svg_lines ...

Maybe I could extract my vertices in a similar way.

[brianzinn]

4 hours ago, babbleon said:

is there a way to check if one particular vertex of a mesh is visible from a camera?

There is an interface called ICullable, which has 2 methods for checking if it's in a frustum:
https://github.com/BabylonJS/Babylon.js/blob/147b793e34a64889b32ab2148834fea3ba92db69/src/Culling/babylon.boundingInfo.ts#L25

Here is a PG that I made using meshes, so not a vertex.  I just want to make sure this is not what you are looking for:
https://playground.babylonjs.com/#050P3M

Camera also has planes that you can use and also camera.isInFrustum() methods that take ICullable.  Although completely inFrustum doesn't make sense for a Vector3, so could be same implementation for both, so I think you can work from those planes and view projection matrix.  There must be a built-in method somebody can give you, but otherwise hopefully that is enough to get you going.  I'm really busy right now or would dig into some math for ya!

[babbleon]

Many thanks @brianzinn - I will have a look later, I am pretty busy today and likely wont have chance to see if I can work with it.

[babbleon]

Here's something which does very vaguely what I'm looking for although very badly - it creates an SVG of the vertices as viewed from the camera including 'hidden' lines.

http://www.babylonjs-playground.com/#7GS1FA#2

 

[babbleon]

This works better: http://www.babylonjs-playground.com/#7GS1FA#4... hopefully on the correct path with this.

http://www.babylonjs-playground.com/#7GS1FA#5

[Sebavan]

Looks good to me ?

[babbleon]

Cheers, @Sebavan... but I'm not quite there with it and so is not solved.

At the moment it just creates a silhouette of each mesh but ignores; intersections, vertices hidden by others etc.

[Sebavan]

np, I was just doing a bit of cleanup before @Deltakosh's return to no be beaten with a stick ?