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Freya Holmér

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11 Sep, 13 tweets, 2 min read

btw these large scary math symbols are just for-loops

dw game dev math mommy's got u ❤

math people interacting with this tweet are just now realizing how little math knowledge game devs and engineers can get by with

okay I go play D&D for a few hours and I come back to my mentions absolutely demolished by Discourse™️, holy heck

lemme clarify a few things I guess:

1. not everyone has the same education or background as you. don't be mean or smug about it

clearly a lot of people know for loops, but not sigma/pi notation

I don't know why you're pretending these people don't exist, and shitting on me for it, given the response to this tweet

2. if you think this tweet amounts to misinformation because it doesn't fully capture what the sigma/pi notation can do - you are part of the problem

this is why people hate pedantry around math

being educational is a very different skill than being comprehensive and rigorous, and they are often in conflict

easing someone into a concept is about leveraging what people already know, not to bombard with academic definitions

3. and yes I know they're not literally the exact same thing, you figured me out, clever you, have a gold star ⭐

how dare I make math more accessible and not include the entire definition of the concepts in a digestible tweet

"but the sigma notation is more flexible than you make it out to be"

yeah well so are for loops? idk why you're being weird about it, I didn't set out to define either of these rigorously

4. math and code are different things that are used for different purposes and both have weird syntax you need to learn

if you only know one of them, there will be some learning required to know the other, because they don't directly translate

one isn't "better" than the other

5. consider untagging me if you want to have debates in my replies because holy heck my mentions are just flooded rn ;-;

6. be kind! people learn things in different ways

and if I can plant a seed that makes someone begin to understand a concept, that's a win to me, even if I didn't plant the seed perfectly

also, watch my bézier curve video for more math stuff visualized with pretty colors ❤️

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More from @FreyaHolmer

Freya Holmér

@FreyaHolmer

10 Sep

generalized bézier curve evaluation using recursion

it returns the point on the curve at t, where P is the set of control points, using recursion starting at B(d,0,t), where d is the degree of the bézier curve (number of points minus 1)

in code:

it's definitely not optimal, but, neither am I

I'm tired and was just curious to see if I could formulate the evaluation recursively in a short lil snippet~

(it evaluates most sub-points twice, among other things)

Read 5 tweets

Freya Holmér

@FreyaHolmer

11 Apr

how do you calculate correct normals when doing vertex displacement shaders?

here's a lil guide/example on the overly complicated but mathematically correct way of doing this~

say you have this simple smoothstep bump, with a radius (r) and an amplitude (a)

the space we're working in will be in uv space, where (0,0) is in the center of this plane

o.uv = the current 2d uv coordinate

d = length(o.uv)
height = smoothstep(r,0,d)*a;

what we need is called the partial derivatives (rate of change) of this function, in order to calculate the normal

now, we're going the unnecessarily accurate route, so we're not using the ddx/ddy functions in the frag shader, that's cheating~

Read 15 tweets

Freya Holmér

@FreyaHolmer

13 Nov 20

@PlayOverwatch

I haven't been able to @PlayOverwatch for a year

it just, doesn't start, and I have *no idea* why

does anyone know what might be the issue?

(thread w. crash log & things I've tried so far that made no difference)

error from windows event viewer

Blizz files:
• Deleted all blizz/OW related things in %appdata%, %programdata%
• Repaired OW
• Reinstalled OW and Battle.net
• Reset OW config
• Deleted Documents/Overwatch

Read 11 tweets

Freya Holmér

@FreyaHolmer

19 Oct 20

(long thread. CW: cynical and depressing introspection)

sometimes it feels like the more you get to know yourself, the more you start questioning what your true self really is, versus what is just a layer of acting you mask it with

I don't even know if that distinction exists

quarantine has made me realize things about myself that I was sort of pretending wasn't there, and now I'm a little uncomfortable admitting that that's really who I am, or if that's even who I want to be, and if I even have a choice

I quit my job as co-founder/tech artist at Neat corp near april, right as covid hit, and we started self quarantining

I don't think I've ever had such an abrupt cutoff from friends that I used to meet every day at work, and from friends I used to meet a few times per year

Read 26 tweets

Freya Holmér

@FreyaHolmer

16 Oct 20

given three points, you can always find a circle passing through them all

1. draw lines from a to b to c
2. draw perpendicular bisectors (dashed)
3. the circle center is their intersection point
4. the circle radius is the distance from the center to any of the three points

this works because

• the circle center is by definition, the same distance to all three points
• given a pair of points, the region where the distance to both is the same, is a perpendicular line between them
• the intersection point is therefore where all three are the same

note that if all three points lie along a line, the circle is undefined! the bisectors would never intersect, so there is no circle passing through all points

(also if you comment about this because you don't read threads I will link you this tweet and make you feel *shame*)

Read 5 tweets

Freya Holmér

@FreyaHolmer

2 Sep 20

there are lot of misconceptions on high refresh rate monitors, so, quick facts!

• the eye doesn't have a "max framerate"
• the eye can absolutely distinguish between 144Hz and 1440Hz monitors

(thread)

the eye is continuously picking up light - if something is moving really fast, then it won't just get a "frame", it will smear in a blur, the size of which depends on the lighting conditions and the properties of your own eye

so - what if something is moving fast on a monitor?

try moving your cursor in a large circle quickly

do you see gaps between the cursors?

double your refresh rate and you would get one more cursor in the middle of those gaps

quadruple and you get three cursors covering that gap

see where this is going?

Read 7 tweets

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