mathr / blog / #

Konstrukt is an SVG + ECMAScript application for compass and straightedge construction. It's not too unintuitive to use, once you know what the controls are:

to draw a straight line through two marked points

press the v key and click on the two points

to draw a circle centered at one marked point through another

press the c key and click on the two points (the first of which is the center)

to delete a marked point and all edges through it

press the x key and click on the point (tip: you might create extra lines and circles for the purposes of deleting at an intersection)

to move the viewpoint

click on empty space to center the view on that position

to zoom in

press the PgUp key

to zoom out

press the PgDn key

New in Konstrukt version 2 are some more attractive drawing tools that are locked to the construction points, useful perhaps for mathematical diagrams like the above 3 octahedra around a line in a 24-cell:

to draw a line segment between two marked points

press the s key and click on the two end points

to change the line segment thickness

press the - key or the + key

to draw a filled polygon

press the f key and click on as many points as you like, then press the z key

to change the fill colour for future polygons

press the [ key or the ] key