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Freya Holmér

@FreyaHolmer

4 Oct

the axis-angle representation of 3D rotation

a single 3D vector, where
• its direction v̂ is the axis of rotation
• its magnitude ||v|| is the angle to rotate by

this can represent any 3D rotation, but you'll most commonly see it represent angular velocity, where the magnitude is the angular speed

this is because unlike quaternions, axis-angle can go beyond a full turn, just like a number representing a single angle can

when representing angular velocity this way, you can also easily add angular velocities together through simple vector addition, decompose it, and project it!

which is pretty neat if you ask me

Read 12 tweets

Freya Holmér

@FreyaHolmer

3 Oct

I feel like so many movies would immediately improve if you removed 80% of dialogue and made it 4 times as long

make me *feel* the character's motivation, and see their struggles and motivations

I'm so allergic to having it told to me over and over through dialogue when it's already clear contextually

and like, it's so hard to have proper pacing and tell a believable story with actual character development, without too much on the nose exposition, in the space of an hour or two

Read 4 tweets

Freya Holmér

@FreyaHolmer

2 Oct

it's just extremely sus that the only people excited about NFTs are very rich famous people, large tech companies, and cryptobros,

while artists themselves are unanimously against the idea

like shouldn't this raise a huge number of red flags?

if twitter truly cared about artists they could help us with two very simple features:

1. let us preview and edit the thumbnail crop region
2. let us tag individual media as nsfw so people can opt out/not be scared of following people who do both sfw and nsfw art

like that's it

also yes of course there are exceptions, some artists are on board with nfts, I know, but they seem to exist as an extremely small minority, that's what I mean by unanimous

so pls stop with the "not all artists" replies now thx <3

Read 10 tweets

Freya Holmér

@FreyaHolmer

11 Sep

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

Read 13 tweets

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

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