Twin Spin

Here’s a regular hexagon inside a regular triangle, that is, an equilateral triangle:

Regular hexagon inside regular triangle


Imagine that two points are moving around the perimeter of each polygon, with the hex-point moving half as fast as the tri-point (after adjustment for the incommensurate relative lengths of the perimeters). If you trace the midpoint of the twin spinning points, you get this shape:

v3v6, 1 : 1/2, pol


And if you adjust the midpoint path as though the triangle had been stretched into a circle, you get this shape:

v3v6, 1 : 1/2, circ, pol


Here’s the same when the ratio of speeds is 1/2 to 1/3, that is, 1 to 2/3:

v3v6, 1/2 : 1/3, circ, pol


Without the polygons, it looks like this:

v3v6, 1/2 : 1/3, circ


When the ratio of speeds if -1/3 to 2/3, that is, the tri-point is moving counter-clockwise around the triangle, you get this shape:

v3v6, -1/3 : 2/3, pol


When it’s stretched into a circle, you get this:

v3v6, -1/3 : 2/3, circ, pol


It looks like a moustache:

v3v6, -1/3 : 2/3, circ


Here are more midpoint shapes created with a hexagon inside a triangle:

v3v6, 2/2 : 3/3, circ


v3v6, -1/2 : 3/4, circ


v3v6, 1/4 : 1/5, circ


v3v6, -1/4 : 3/4, circ


v3v6, -1/4 : 4/5, circ


v3v6, 2/3 : 3/4, circ


v3v6, 2/3 : 3/5, circ


v3v6, 3/4 : 4/5, circ


v3v6, 3/4 : 4/5, circ


Now try aligning the nested hexagon like this, so that the sides of the hexagon coincide with the middle third of the sides of the triangle:

v3v6, side alignment


With two points moving in a ratio of 1/3 to 1/4, you get this midpoint shape:

v3v6, sided, 1/3 : 1/4, pol


Here it is without the polygons:

v3v6, sided, 1/3 : 1/4


Now try a regular octagon inside a square:

v4v8, 1/2 : 1/3, circ, pol


v4v8, 1/2 : 1/3, circ


v4v8, -1/3 : 3/4, circ


v4v8, 2/3 : 3/5, circ


Now place a triangle inside a hexagon:

v6v3, 1 : 1/4, pol


If you stretch the midpoint path according to perimeter of the triangle, you get this:

v6v3, 1 : 1/4, circ, pol


v6v3, 1 : 1/4, circ


The three stretching shapes remind me of hands in Egyptian art, like this image of King Tutankhamun and Queen Ankhesenamun:

Detail from the Golden Throne of Tutankhamnun


Here are more midpoint paths:

v6v3, 1 : -1/4, circ


v6v3, 1 : 1/2, circ


v6v3, 1 : 1/3, circ


v6v3, -1 : 1/3, circ


v6v3, -1 : 1/4, circ


v6v3, 1 : 1/5, circ


v6v3, 2/3 : 1/4, circ


Now try a square inside an octagon:

v8v4, 2/3 : 1/4, circ, pol


v8v4, 2/3 : 1/4, circ


v8v4, 2/5 : 1/6, circ


v8v4, 2/5 : 3/7, circ


v8v4, 4/5 : 3/7, circ


Elsewhere Other-Accessible…

First Whirled Warp — an earlier look at this kind of geometry
Second Whirled Warp — and another earlier look

Second Whirled Warp

In “First Whirled Warp”, I looked at the paths traced by the midpoint of two points moving at varying speeds around the perimeter of a circle or polygon. Now I wanted to look at the midpoint of two points moving on the perimeter of a star. Suppose the star looks like this:

Four-pointed star


If the two points start at the same vertex and one point is moving 1/2 as fast as the other, the midpoint traces a shape like the head of a fox:

Fox-head from midpoint of two points moving in speed-ratio 1/2 : 1 (or 1 : 2)


If one point is moving 1/3 as fast (or 3x faster), the trace looks like this:

Midpoint of two points moving in speed-ratio 1/3 : 1


And if the points are moving -1/3 : 1, that is, in opposite directions (one clockwise, one widdershins):

Speed-ratio -1/3 : 1


And you can adjust all pixels outward so that the outer vertices of the star lie on the perimeter of a circle:

Speed-ratio -1/3 : 1 (circular)


Here are more traces created by the midpoint of two points moving around the perimeter of a four-pointed star:

Speed-ratio 1/5 : 1


Speed-ratio 3/5 : 1

Speed-ratio 3/5 : 1 (circular)


Speed-ratio -3/7 : 1/3

Speed-ratio -3/7 : 1/3 (circular)


Speed-ratio 7/3 : 6/7

Speed-ratio 7/3 : 6/7 (circular)


Speed-ratio -7/3 : 6/7

Speed-ratio -7/3 : 6/7 (circular)


If the star is adjusted like this:

Variant on four-pointed star


You can get mid-traces like this:

Speed-ratio -1/7 : 1 (adjusted star)

Speed-ratio -1/7 : 1 (adjusted star) (circular)


Here’s a three-pointed star:

Speed-ratio -4/5 : 1 (3p star)

Speed-ratio -4/5 : 1 (3p star) (circular)


And some five-pointed stars:

Speed-ratio 2/7 : 1 (5p star)

Speed-ratio 2/7 : 1 (5p star) (circular)


Speed-ratio -7/5 : 3/7 (5p star)

Speed-ratio -7/5 : 3/7 (5p star) (circular)


Previously Pre-Posted

First Whirled Warp — an earlier look at points performativizing on perimeters