# Message #3948

From: Melinda Green <melinda@superliminal.com>

Subject: Re: [MC4D] POLL: Positive rotation convention

Date: Wed, 10 Jan 2018 17:48:41 -0800

In the immortal words of Jayne Cobb: "We’re gonna explode? I don’t wanna explode!"

I’m therefore of the same mind as Luna.

Regarding MC4D, I think the reason the current way feels right is because pressing a mouse button feels like pushing /down /on the left or right edge of a circle or sphere centered on the mouse. In other words, it’s because of how mice physically work and nothing to do with handedness or coordinate systems.

-Melinda

On 1/10/2018 12:51 PM, Luna Peña scarecrowfish@gmail.com [4D_Cubing] wrote:

>

>

> I would be in the speedcuber’s camp on this one, being one myself, although I must say that I could probably adjust to the other way. Honestly, most of the notation I use for 4D puzzles is different to yours anyway, and so I was planning to just translate.

>

> In terms of swapping left and right click, the current way round make sense to me not as positive and negative, but that right ‘feels’ clockwise to me, and left ‘feels’ anticlockwise. I’m not sure why, but it’s not just since using MC4D. I honestly associate right click with positive as it’s the clockwise twist, and so your third anticlockwise arguments seems pointless to me.

>

> Just my thoughts.

>

> ~Luna

>

> On 10 Jan 2018 20:45, "Joel Karlsson joelkarlsson97@gmail.com <mailto:joelkarlsson97@gmail.com> [4D_Cubing]" <4D_Cubing@yahoogroups.com <mailto:4D_Cubing@yahoogroups.com>> wrote:

>

> Hello,

>

> While discussing notation (primarily) applicable to 4D-puzzles (including the physical 2^4) with Marc, we encountered a decision of convention which we could not decide ourselves. Therefore, I want to start a poll to gather the community’s opinion.

>

> The question is: should the positive direction of rotation of a cube or a cell of a cube be clockwise or counterclockwise? The rotation is assumed to be performed in 3D-space. With the "positive direction of rotation" I mean the assumed direction of rotation around an axis if nothing else is specified. Ox is a positive rotation and Ox’ is the opposite negative rotation; which do you think should be a clockwise rotation and which should be a counterclockwise rotation around the positive x-axis?

>

> I’ll leave the arguments below. If you have an opinion or preference please respond to this post with something like "I think that [insert your preference here] should be the positive direction of rotation… [insert arguments here if you wish]".

>

> Best regards,

> Joel

>

> PS. I don’t know how long the poll should be open, we’ll see when the reply-rate drops.

> PPS. If everyone is fine with that, I’ll leave my vote as a casting vote in the event of a tie.

>

> *Clockwise (arguments)

> *

> The speedsolvers’ convention: Regarding x versus x’ turns being clockwise, we speedsolvers have read so many dozens (hundreds) of pages using our notation that it is wired right into our brains. So, instead of our criterion for the best notation being "what seems objectively reasonable, in principle", our criterion is "what will not make our heads explode by being the exact opposite of what we use daily in a very similar context…"

>

> As an example, here are a couple of typical pages from speedsolving.com <http://speedsolving.com> – a page for a random beginner method, and one of the most commonly used reference pages for the last stage of many people’s solves.

>

> https://www.speedsolving.com/wiki/index.php/8355_Method <https://www.speedsolving.com/wiki/index.php/8355_Method>

> https://www.speedsolving.com/wiki/index.php/PLL <https://www.speedsolving.com/wiki/index.php/PLL>

>

> These pages use the notation as defined here,

>

> https://www.speedsolving.com/wiki/index.php/3x3x3_notation <https://www.speedsolving.com/wiki/index.php/3x3x3_notation>

>

> and use x, y, and z to refer to clockwise turns of the entire cube around the relevant axis.

>

>

> My argument is not that the speedsolving community is our largest or most important subcommunity, but that it is the group to which this decision makes the biggest daily difference. If there’s a subcommunity of MC4D who read lots of recipes in which "z" means a counterclockwise turn around the z axis, then my argument will be invalid on its face… If not, then we’ll have to decide whether there is a reasonableness argument that can override the practical difficulties for speedsolvers in dealing with two opposite conventions used so similarly.

>

> *Counterclockwise (arguments)

> *

> 1) For a mathematician or a physicist, the positive direction of rotation is, conventionally, counterclockwise. Always, when talking about rotations in topics ranging from linear algebra to mechanics the axis of rotation is defined in such a way that a rotation (of a positive number of degrees) around that axis is a counterclockwise rotation.

>

> 2) It follows the right-hand rule. This is a simple rule which helps the forgetful to remember in which direction to rotate; if your right thumb is the axis of rotation the fingers curl in the direction of rotation.

>

> 3) It’s consistent with MC4D. A left click on a sticker in MC4D rotates the cell counterclockwise around the axis pointing from the centre of the cell through the specified sticker. This implies that Ux is performed by left-clicking on the right sticker on the U-cell and the same goes for all other twists. The axes (in the notation) can be thought of as specifying a sticker on the cell (Fx’yz specifying the sticker (on the F cell) in the negative x-direction (left), the positive y-direction (up) and the positive z-direction (front)) and the twist is performed by simply left-clicking on this sticker.

>

> *A third option?

> *

> No, I don’t have a third option but there is something which could potentially be a game-changer. If an option to swap the behaviour of left- and right-click would be available in MC4D the third argument for counterclockwise would fail. This argument could then instead be used by the clockwise camp since G already breaks the MC4D convention (the axis in the G moves specify the direction in which the stickers should move and ctrl+left-clicking on a cell in MC4D rotates the cube in the opposite direction) and therefore, all moves (including G) would follow the MC4D convention if clockwise is the positive direction of rotation and the controls are swapped (or you prefer right-clicking to left-clicking).

>