Struggling to find good explanation on how to create a triangle from given points

Ukendio · December 30, 2019, 7:05pm

I have been scripting for a while, not really tapped into CFrame advanced side THAT much yet. I have however read axisangle’s take on it, which was very informative. I figured I would be able to use this information to write a script that generates triangles but I am very baffled on what to do.

I have read a dozen articles about this, however I couldn’t find anything to explain the in-depth logic. I have found a few open-source codes to these scripts but since I don’t understand them, I can’t utilise them to their full extent.

If there’s any guide that could walk through the whole process of writing a triangle creator - that would be exactly what I am looking for.

Thanks <3 for at least reading this plebian’s cry for help. I have always gotten support so quickly and I really do appreciate it. Happy new years ^^

K_reex · December 30, 2019, 7:06pm

This article by @EgoMoose gives a fairly good explanation on how the math works.

It really helped me when I was looking into this.

github.com

EgoMoose/Articles/blob/master/3d triangles/3D triangles.md

# 3D Triangles

On occasion you may find it necessary to draw triangles given three points in 3D space. This article aims to go over one method that can be used to create those triangles using knowledge of trigonometry and coordinate frames.

## Table of contents

* [Triangle decomposition](#triangle-decomposition)
* [Manipulating the rotation matrix](#manipulating-the-rotation-matrix)
* [Optimization](#optimization)

## Triangle decomposition

The first thing we need to be aware of is that Roblox does not have a singular default shape that can be used to create any 3D triangle. However, a shape that Roblox does have is right-angle triangles, otherwise known as wedges. Thus, we can decompose any triangle into a maximum of two right-angle triangles and draw from there. We can easily draw this process by placing a perpendicular line on the longest edge and having it intersect with the opposite vertex.

![img1](imgs/img1.png)

Now that we understand the basics of our goal we have to ask ourselves how we can achieve this mathematically. We'll start this process off by finding some information about the triangle depending on what side is the longest.

![img2](imgs/img2.png)

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EDIT

If what you’re looking for is generating triangles from a grid of vertexes, I can also help you with that, but I’m not sure if that’s what the OP is asking.

Jaycbee05 · December 30, 2019, 7:08pm

To create a triangle with given vertices you could look into Polygon Triangulation( if you haven’t already) , i am not sure what you are trying to achieve though

Ukendio · December 30, 2019, 7:16pm

I was looking for was an explanation HOW to accomplish making something like that. I don’t want the product, I want to learn to make the product (… as they: give a man a fish and you feed him for a day; teach a man to fish and you feed him for a lifetime).

Though the source is helpful to affirm my (…knowledge) so thanks for the input anyway.

K_reex · December 30, 2019, 7:26pm

I’m not sure if you were replying to only @Jaycbee05 or both of us, but the article I provided does give an explanation of everything that is happening.

What part, specifically, are you trying to understand?

If you are still struggling with how everything works you might want to look into vector math:

Ukendio · December 30, 2019, 7:29pm

I was replying to @Jaycbee05 (that is why it has that reply sign )

EgoMoose · December 30, 2019, 7:34pm

Im still not entirely sure what you’re looking for? If you want polygon triangulation then just search for some algorithms from the wikipedia page.

Ukendio · December 30, 2019, 7:37pm

I want to understand polygon triangulation, and how it works and how I can implement it in roblox (by myself). I don’t want a finished set of code.

EgoMoose · December 30, 2019, 7:41pm

Usually explanations include finished sets of code Or at least pseudo code. I’d recommend you take the wikipedia article Jaycbee linked and google search explanations of those methods/algorithms.