I have some imported stl objects in my scene. They are looking quite different, but for example i will talk about the orange one in this example https://threejs.org/examples/?q=stl#webgl_loader_stl . At the moment im able to click on the object with the mouse, object gets selected and i can do whate…

Hi, welcome to the forum. You’ll need to use the triangle information to know which triangles are neighbours of which ones, and also know the angles between them, to separate the boundary that forms the feature you want. I will write you an algorithm in pseudocode (which means it is not written in…

Hello yombo, First i want to thank you very much. Its awesome that ppl like you are so kind and take their time to help others. I’ve been analysing your code and except a little thing i think it should work. After: if N is not empty: Add N to A, if they are not already in AND if they are in U. S…

Hi, you are welcome :slight_smile: I wrote “Let N be the set of triangles from U…”, so no need to check if they are in U, we took them from U already. 1 . The THREE.Raycaster gives you information on the intersection point, the face intersected and more. 2 . For this to work it is much more usefu…

Thank you very much again. On monday i am going to start implementing this. Is it necessary to convert to an indexed array? when i have to search for these 6 combinations (a,b,?),(b,a,?),(a,?,b),(b,?,a),(?,a,b),(?,b,a) by going through the whole array, it doesnt matter if its sorted, except i don’t…

[image] anon81599084: when i have to search for these 6 combinations (a,b,?),(b,a,?),(a,?,b),(b,?,a),(?,a,b),(?,b,a) by going through the whole array, it doesnt matter if its sorted, except i don’t have to search through everything:). Yes, there are lots of possible optimizations, as that one…

And btw, good luck with it :slight_smile:

Thank you! I will let you know of course if i was successful or not😊. Also thank you very much for your time! Very kind!

So i started implementing today and i already have some questions. I don’t find a method for transforming BufferGeometry to an indexed one here https://threejs.org/docs/index.html#examples/en/utils/BufferGeometryUtils , so I use this code https://threejs.org/examples/webgl_buffergeometry_indexed.html …

Hey i have some new knowledge: Finding neighbours should probably be done by comparing vectors. So you can’t compare indices and find out neighbours because they are not sorted like that in the array. So you have to search them in the position array. The problem is now, i want f.e. to splice out a …

[image] anon81599084: So my third question is: do i have to compare these indicices with the ones reated? The (a,b,?), (b,a,?) thing is with indices. The indices array works 3 by 3, with each three indices forming a triangle. For example: If you have triangle (15, 16, 30) and find a triangle…

Thank you, you are right. But do you know how to index a complex object? In the three.js “indexed” example it looks pretty easy because the triangles are all known, but how can i generate an indexed buffergeometry, by not knowing, which vertices in geometry.attributes.positions are building a triang…

Compute surfaces of objects

Questions

yombo November 9, 2019, 7:09pm 7

And btw, good luck with it

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Compute surfaces of objects

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