sketch-helpers

A number of 2d sketch helpers, they are 100% pure functions, no state to be found here.

I seemed to be obsessed with sketch helpers in Code-CAD applications, not only do I have this OpenSCAD library, but I also tried to add the following helpers to CascadeStudio. Unfortunately the latter was never merged, but I still think these are valuable at least to me. I'm likely to try and use these again at some point. I wouldn't consider this repo to be maintained, it's more "here for longevity".

I'm no TDD fanatic, but the methodology absolutely was a great help in this case. One challange I hit was with the test text, since tests serve double duty, primarily testing logic, but secondarily documenting the code, it can be hard to describe specific geometric secenarios, so I leveraged multiline template strings and everyone's favourite, 'ascii art', to draw the expected result.

Here's a dump of the test output to show what I mean:

``
PASS src/index.test.ts
testing calculate3Points
When the target angle is -90
✓ When clockwise and obtuse expect
.-------------------------------- ~ - , startPoint
. ' ,
. , onArc
. ,
. ,
. , - endpoint
(3 ms)
✓ When clockwise and acute expect
. , - ~ ~ ~ - ,
. , ' ' ,
. , onArc ,
. , ,
. , ,
. , , endPoint
. ,
. ,
. ,
. ,
.______________________ ' - , _ _ startPoint

✓ When CCW and obtuse expect
. , - ~ ~ ~ - ,
. , ' ' ,
. , , onArc
. , ,
. , ,
. , endPoint ,
. ,
. ,
. ,
. , '
._____________________________ _ _ _ , startPoint
(1 ms)
✓ When CCW and acute expect
.-------------------------, - ~ ~ startPoint
. , '
. , onArc
. ,
. ,
. , endPoint
(1 ms)
✓ When shortest and obtuse expect
.-------------------------------- ~ - , startPoint
. ' ,
. , onArc
. ,
. ,
. , - endpoint
(1 ms)
✓ When longest and obtuse expect
. , - ~ ~ ~ - ,
. , ' ' ,
. , , onArc
. , ,
. , ,
. , endPoint ,
. ,
. ,
. ,
. , '
._____________________________ _ _ _ , startPoint
(1 ms)
✓ When shortest and acute expect
.-------------------------, - ~ ~ startPoint
. , '
. , onArc
. ,
. ,
. , endPoint
(1 ms)
✓ When longest and acute expect
. , - ~ ~ ~ - ,
. , ' ' ,
. , onArc ,
. , ,
. , ,
. , , endPoint
. ,
. ,
. ,
. ,
.______________________ ' - , _ _ startPoint

When the target angle is 90
✓ When clockwise and obtuse expect
.---------------------------- ~ ~ - , startPoint
. ' ,
. ,
. ,
. ,
. , endPoint ,
. , ,
. , ,
. , ,
. , , ' onArc
. ' - , _ _ _ , '

✓ When clockwise and acute expect
. , endPoint
. ,
. ,
. , onArc
. ,
.______________________' - , _ _ startPoint

✓ When CCW and obtuse expect
. , endPoint
. ,
. , onArc
. ,
. , '
._____________________________ _ _ _ , startPoint
(1 ms)
✓ When CCW and acute expect
.------------------------, - ~ ~ startPoint
. , '
. ,
. ,
. ,
. , , endPoint
. , ,
. , ,
. , onArc ,
. , , '
. ' - , _ _ _ , '
(1 ms)
✓ When shortest and obtuse expect
. , endPoint
. ,
. , onArc
. ,
. , '
._____________________________ _ _ _ , startPoint
(1 ms)
✓ When longest and obtuse expect
.---------------------------- ~ ~ - , startPoint
. ' ,
. ,
. ,
. ,
. , endPoint ,
. , ,
. , ,
. , ,
. , , ' onArc
. ' - , _ _ _ , '
(1 ms)
✓ When shortest and acute expect
. , endPoint
. ,
. ,
. , onArc
. ,
.______________________' - , _ _ startPoint
(1 ms)
✓ When longest and acute expect
.------------------------, - ~ ~ startPoint
. , '
. ,
. ,
. ,
. , , endPoint
. , ,
. , ,
. , onArc ,
. , , '
. ' - , _ _ _ , '

testing calculateIntersectionOfTwoLines
✓ two 45 degree angles
✓ horizontal and vertical line (1 ms)
✓ horizontal and angled line
✓ vertical and angled line (1 ms)
testing offsetLine
✓ vertical line going up positive offset
✓ vertical line going up negative offset
✓ vertical line going down positive offset
✓ vertical line going down negative offset
✓ horizontal line going right positive offset
✓ horizontal line going right negative offset (1 ms)
✓ horizontal line going left positive offset
✓ horizontal line going left negative offset (1 ms)
✓ angled line line positive offset
✓ angled line line negative offset (1 ms)
testing intersectionWithParallelLine
✓ 45 degree angle with offset and a vertical line
✓ two 45 degree angles, one offset
testing pointToTangent
✓ When clockwise tangent (1 ms)
✓ When counterCW tangent (1 ms)
✓ When point is very far away from small circle, both points for clockwise and not should be close to 2*radius apart
testing getTangentialPointOfTwoCircles
✓ when small to big clockwise circles where their tops are horizontal (1 ms)
✓ when big to small clockwise circles where their tops are horizontal (1 ms)
✓ when swapping the placement of the circles should mean the tangent runs along the bottom, and angle should be 180 (1 ms)
✓ when small to big counterCW circles where their bottoms are horizontal
✓ when circles of the same radius at 45deg angle
✓ when tangents are transverse, circles arranged such that tangent should be flat, first circle clockwise (1 ms)
✓ when tangents are transverse, circles arranged such that tangent should be flat, first circle counterCW (1 ms)
`

To run the tests yourself
`
yarn install
yarn test
``