Flocking | 3D Flocking Simulation | Graphics library

I have a boids flocking simulation setup. It originally worked by having every boid loop through every boid so that they all constantly know where each other are at in order to tell if they are close or far away, but then I switched to a quadtree design so that boids only have to loop through boids that are actually nearby. However, it has made virtually no improvement to the simulation's FPS. It's as if I'm still looping through every single boid.

Is there some mistake in my implementation? Repo is here, relevant code is mostly in main.js, quadtree.js, and boid.js. LIve site is here

I am writing a model in NetLogo where I start with a 5 turtles populations in colours (blue, green, yellow, red, white) with random starting co-ordinates. When I run the model, I want when the white turtle meets the green or yellow or red turtle, they become joined with it and move together as a group. And when the white turtle meets the blue turtle, it separates from it and both continue moving randomly. I saw the example model for bird flocking in the model library and I have been trying to modify it for my model (see code attached).

In the 'flocking example' from the models' library, turtles are set to align, cohere and separate when too close to each other (depending on the distance for the nearest-neighbour and minimum-separation). This works well and I was able to use it to tell turtles to flock, keeping them intact as a group as they continue to move. My question is how to get only the (green, yellow, red) turtles to flock when they meet the white turtles and leaving the blue turtles moving randomly.

I am studying flocking behavior in netlogo, and in order to keep track of various flocks I am using a hidden "flock-holder" turtle that I can hatch or let die if a new flock is created or an existing flock runs out of members. I am coming across an issue however, where on occasion when I am trying to interface with some data within a flock, as referred to through an individual member of a flock, I get a message saying "That is dead", causing the code to fail.

From what I understand of the "die" command, if a turtle of any kind dies, it should remove itself from any agentset or variable that references it, and therefore this sort of error shouldn't be a problem? How can I fix or at least debug this strange issue?

Code of my flock-evaluation function that is having the issues below:

I am designing a boid system using Unity. I deal with the awareness radius by adding a boid to the "Swarm" list when it enters a collider. In order to find the force for each boid, I need to cycle through the swarm list, access the "Boid" class, and retrieve velocity and position.

The Boid classes from each swarm entity are added to a new list, and passed to the physics controller. However, a NullReferenceException is thrown at line 96, and I don't understand why that variable would be null. As far as I know, accessing a populated Enumerable using foreach should have variables within.

NullReferenceException: Object reference not set to an instance of an object Boid.Alignment (System.Collections.Generic.IEnumerable`1[T] boids) (at Assets/Scripts/Boid.cs:96) Boid.Update () (at Assets/Scripts/Boid.cs:42)

After testing, it seems it is thrown when accessing any part of the new list of Boids.

Why does my new list contain no data? Is there a better way to handle a 2D implementation of boids in a 3D space? Is there a resource I can use to better understand Linq?

P.S. I am very new to using Linq systems, and most of this code is taken from this video and this Unity project script

I'm a very new coder, honestly confused most of the time, Any advice would be great. I was doing an exercise from Dan Shiffman vids. I’m trying to paint a line or a stroke with pixel data from a live webcam. Two canvas, one live webcam tiny and a large canvas that has a lot of ellipse that are colored in pixel rgb from pixel array This is an image of my final product

I made a separate file for the particle and then used a constructor function and a loop to display and update in draw(), while in the particle file I tried to use a line instead of an ellipse by using an array of past positions of the object. However, it won’t work? The canvas just appears grey. In the particle.js file, when I used the line() function, and when I use the ellipse() I don't get a painterly brushstroke effect, Not sure if my logic is correct. Here is the code -> I’m sorry there's a lot. The first bit is the particle.js file and the second is the main sketch file.

I'm trying to run a flocking simulation like this one from the coding train.

I was thinking I might be able to speed things up by running my code in a separate asynchronous loop in parallel to the p5 draw loop. My simulation code could update the positions of the boids and the p5 code could draw the boids. That way, the draw loop wouldn't have to be slowed down by the simulation code and my code wouldn't have to be slowed down by the drawing.

A) Do you think that would actually speed up the simulation or at least allow p5 to draw at a higher frame rate? and B) How would you run the two in parallel?

Thanks for your help!

I have a parent object (Flock) with a public List of child objects (Boids). I need each Boid to be able to check that list every Update() for nearby neighbours so I can implement some flocking behaviour.

Ive now been stuck for over 2 weeks on how to drag and drop multiple items at once within a collectionView (ie reordering multiple items within a collectionView) using the new ios11 drag & drop protocols. I can't get the cells to consistently reorder correctly.

Ive tried using placeholders but that appears to be more targeted for remote drags into a collectionView with async data loads.

Ive tried following instructions given in an answer within a blog post

https://hackernoon.com/drag-it-drop-it-in-collection-table-ios-11-6bd28795b313

where the instructions given (as an answer in the list of questions at the end of the post) was as follows

Reordering multiple items in the same collection view is a bit tedious and need to be handled manually.

First of all, use UICollectionViewDropIntent as .unspecified for .move UIDropOperation in the UICollectionViewDropProposal while returning from collectionView(_:dropSessionDidUpdate:withDestinationIndexPath:), i.e.