Ono-Sendai

The belt trick is about smoothly mapping paths through SO(3) to each other, not about if any point in SO(3) is reachable from any other point. I think you are confusing the notion of 'simple-connected' with just 'connected'.

I think you are confused about what 'simply connected' means. A 3x3 matrix can represent any rotation. Also from a given rotation there is a path through the space of rotations to any other rotation. It's just that some paths can't be smoothly mapped to some other paths.

Cool. If you want to try rendering some flame fractals, you can try our Fractal software Chaotica (https://www.chaoticafractals.com/) which was used to make the first image in the linked post (Vorpol Dawn By technochroma).

We didn't exactly use compute shaders for Chaotica, we used OpenCL instead, which is a more general GPGPU framework like CUDA.

That's wild. My 9950X died for some reason, never overclocked.

I would love this. I have to do disgusting hacks to get an embedded browser window in my metaverse (https://substrata.info/) that uses webgl. The disgusting hack is to render the browser window behind the main webgl canvas, and then punch a hole through the webgl canvas with zero alpha. Event handling (mouse, keyboard) is also a total pain.

compute shaders?

Very nice. It seems some of the algorithms are (inadvertently?) solving the shallow water equations. Looks similar to the results I was getting working on https://github.com/Ono-Sendai/terraingen

Also the Normans were vikings!

Substrata - an open-source metaverse. https://substrata.info/, https://github.com/glaretechnologies/substrata

Custom high performance C++ / OpenGL/WebGL engine. Uses Jolt physics and Luau and Winter scripting.

It's a lot of fun and pretty challenging code.

What I don't get about this timescape theory, is what is the mechanism for time passing faster in the 'voids'? Or equivalently, what makes time pass slower along the edges of the voids? Is it supposed to be gravitational time dilation? (e.g. 'low is slow') Surely this can't have an effect of this magnitude (a 2x speedup in the voids)? As I understand it gravitational time dilation only has significant effects (like the 2x slowdown) in the strong gravitational region regime, around black holes etc.

Not really proper 3D, more like a kind of 2.5D.

Anyone else notice how the entropy in the 1000 bouncing balls simulation goes down at some point, thereby violating the second law of thermodynamics? :)

A more reasonable reply would be something like, "wow, that's cool that you got a 4x speedup. A 4x speedup is certainly enough to justify using floating point maths. And the code is simpler too!"

"Sure, a compile-time option to use one or the other might sound reasonable, but then that's two different code paths that need to be maintained and tested. Are you willing to do that maintenance on an ongoing basis?"

No, that's why I will change to a better font rendering system when I get a chance.

I don't think you understand how backwards it is. My patch that makes SDF rendering 4x faster was not accepted, presumably because floating point-maths is some strange new-fangled technology. Freetype uses antiquated fixed-point integer maths everywhere. See https://gitlab.freedesktop.org/freetype/freetype/-/merge_req...

FreeType is a dinosaur that should be replaced regardless of Rust or not.

that's hilarious, thank you. The life of a c++ programmer using dodgy libraries.

whisper

Yeah interesting question. Presumably you can do it by having a border around each region, and a max speed of effect propagation (i.e. causality). Then if you want to simulate e.g. 10 time steps, you have a border of 10 grid cells. So do 10 time steps on each region, then synchronise border state with other parallel border sims. Then rinse and repeat.

thanks :)

I also released something similar recently, with random heightfield generation and sediment transport and erosion too: https://github.com/Ono-Sendai/terraingen

Yeah but if your dithering is noticable in the first place you're doing it wrong.

What is the point of this?

Re: the menstruation app one - instead of spending 870 k talking about what they would like to see in a menstruation app, just make one. It's not rocket science.

re: the transgender one, it seems to be one of these social science projects that just involves interviewing people. From the project page: "This discourse-based research will interview twelve transgender young people". Is interviewing 12 people for $870,000 NZD a good use of money? I don't think so.

Cutting all blue-sky social science research does seem to go a bit far. On the other hand, I'm not sure NZ needs this:

"The intimate technology shaping millions of lives: Exploring the possibilities of menstruation and perimenopause tracking apps for people with diverse embodied experiences." - 870k NZD

"It takes a village: Picturing family support for transgender young people in Aotearoa" - 870k NZD

"Sensationalising Sleep: Discourses and practices of sleep in Aotearoa" - 360K NZD

etc..

From the Marsden fund 2022: https://www.royalsociety.org.nz/what-we-do/funds-and-opportu...

Yeah, we may have to take seriously that the notion of complexity for a finite string (or system) has no reasonable definition.

You are correct to be bugged IMO, I agree with you. My thoughts: https://forwardscattering.org/page/Kolmogorov%20complexity

Kolmogorov complexity is useless as an objective measure of complexity.

The first thing to understand is that multiplying a complex number by i rotates the complex number by 90 degrees counter-clockwise around the origin. For example, 1 * i = i (e.g. 1 + 0i is mapped to 0 + 1i). And i*i = -1 (e.g. 0 + 1i is mapped to (-1 + 0i) and so on. e^ix is a continuous generalisation of this discrete rotation, as I understand it.

It's not just you. Dirac fields are constantly rotating. In fact the solutions are called spinors. (e.g. things that spin). There are a lot of rotations at the quantum level. It's also why complex numbers show up a lot in q.m.

She seems to be talking about spacetime itself being Lorentz contracted though.

it's true that a sufficiently fast moving object would be length contracted so much that it started interacting with the minimal LQG length, which would violate Lorentz invariance. Depending on how big the LQG loops are, that could be a fanstastically high speed that isn't achievable in the universe though.