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Comment by jakegmaths | Hacker News Reader

I loved tixy when I first discovered it a few years ago so created this https://www.mathsuniverse.com/tixy (with permission from the original author) with puzzles to solve on the tixy grid. I use it with my computer science students who get really into it.

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Reminds me of [Replicube](https://store.steampowered.com/app/3401490/Replicube/), which has released recently and does the same kind of thing in 3D.

This is a cool way to teach!

I was blown away by the little functions at first and I too made a clone to experiment with calculang [1].

I added an evaluation feature (F9) so you can select sub-expressions and see what they do, which was helpful to figure out some patterns (video in [2])

[1] https://calculang-editables.netlify.app/tixyish

[2] https://www.youtube.com/watch?v=uXUd_-xrycs

I've been programming for over 40 years, and I can say this is the most fun way I've experienced to learn this kind of thing. It really is fun.

My 5yo did great on these until he hit #7 and got stuck! I’m helping him with syntax but trying to hold back from giving conceptual hints for now.

I love the instant visual feedback!

Why isn't "(sin(i) * (x > 7)) - (i == 5) + (i == 20) + 0.5 * (i == 32)" a solution to puzzle 36?

Fun. Thanks!

Works well on phone. The phone keyboard is a bit clumsy but it works (that’s a phone issue)

Well done!

> In computer graphics, the origin (0, 0) is top-left rather than bottom-left

Umm...

What's wrong with that statement? It has historically and traditionally been true for raster displays, even if there do exist ways to use standard Cartesian-style coordinates with a computer.

There top left has usually been (0, 0) for hardware pixel coordinates (although even then there’s plenty of exceptions, e.g. mode 13h scrolling) but as a blanket statement about computer graphics in general it’s misleading.

I'm struggling to see the problem with this statement, other than maybe to add in the word "usually". My students will know of graphs in maths where the origin is always bottom left. When working with HTML canvas and every other computer graphics situation I've worked in, it's top left instead.

"PostScript uses a coordinate system where the origin is at the bottom-left corner of the page, with the x-axis increasing to the right and the y-axis increasing upwards."

Oscilloscopes use middle-left.

Unreal engine and SketchUp use Screen middle with xy increasing to the right.

in AutoCAD, the user coordinate system is 1/3 of the screen to the left for the origin, with X increasing to the right, and Y increasing upwards.

Almost all raster displays, and memory based programs assume top left, because that is how it was done first - counter intuitive.

It it not counter intuitive and the decision extends far earlier than the first displays.

A raster image onscreen is displayed in the order that the data appears when written down. It stands to reason that a data depiction should be in the same orientation as the display orientation. Displays were created by people who read from left to right, top to bottom. If the displays did not follow that order. images would be flipped or rotated when displayed in a data form.

The first pixel written to the display is in the top left because we read from the top left. If writers of another language had have popularised the text, perhaps things might have been different.

Why does the BMP file format store the image upside-down though?

IBM brain rot adopted by Microsoft.

Why are device-independent bitmaps upside down? Raymond Chen https://devblogs.microsoft.com/oldnewthing/20210525-00/?p=10...

I think you had to wait for WinG or maybe even DirectX to get normal 1:1 mapping.

OpenGL is so old it had same stupid ideas about coordinates.

> When working with HTML canvas and every other computer graphics situation I've worked in, it's top left instead.

In OpenGL is (center, center)

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