Cue Angles

Cue Angles is an aiming trainer for pool. The physics, the lessons, the drill
layouts and every word of text live inside the app. No ads, no network, no
account, and nothing to buy: every part of the app is open from the first
launch.

THE NUMBERS ARE REAL
Every shot is worked out by the app's own physics before the animation starts:
balls of 57.2 mm, pocket mouths of 114 mm, a 2 ms integration step, elastic
contact along the line of centres, throw from friction between the balls,
squirt from the tip offset and cushions that mirror the line. The same shot
always gives the same path, so a miss can be split into the parts that caused
it.

A BREAKDOWN, NOT A VERDICT
After every shot you get the aim error in degrees with its sign, the contact
point in millimetres against the one you needed, how far from the centre of the
pocket the object ball passed, and which of aim, throw, squirt or cushion took
the angle away, each in degrees. The ideal path is drawn over the one you
played. Those numbers are read out of the shot you just played, not estimated
afterwards.

SIX MODULES, THIRTY LESSONS
Cut angles and the ghost ball; contact point and the tangent line; rail
reflection; side spin and throw; position and the 30 degree rule; combinations,
kisses and safeties. Each module has five lessons with diagrams drawn on the
same table you play on, and all six are open from the first launch.

120 DRILLS IN FOUR LEVELS
Twenty layouts per module, cut into four levels of five. Level 1 stays under a
15 degree cut; level 4 goes to 70 degrees, adds two cushions and asks where the
cue ball finishes. A drill is passed by potting the named ball in the named
pocket inside the shot limit with the aim inside the level's tolerance - 2.5
degrees on level 1, 0.8 degrees on level 4. The next level opens after four of
the five below it are passed.

EVERY MISS COMES BACK
Miss a drill and it returns tomorrow. Pass it first time and the gap grows to
three days, then seven, sixteen and thirty-five. Two clean passes at the last
two intervals retire it. Review collects what is due today, oldest miss first,
8, 15 or 20 drills a session as you choose.

ANGLE LAB
A table with no task: place the balls where you want, pick a pocket, read the
cut angle, the contact point and how far the cue ball comes off its own line,
and keep up to 20 of your own layouts on the phone.

MADE FOR ONE HAND
Drag the aim line on the cloth, then trim it a twentieth of a degree at a time.
Pick the tip position on a 5x5 or 7x7 grid, the cue elevation and the power.
Tables of 7, 8 or 9 feet, millimetres or inches, three cloth colours and a
left-handed layout that mirrors the whole panel.

WHAT YOU ARE COUNTED ON
Shots and pots by level, average and best aim error, average aim error by cut
angle band, which way the misses went, drills passed by module, a 90 day
activity calendar and a plain text export of all of it, written into the app on
your phone.

NOTHING IS FOR SALE
There is no store in this app, no price anywhere in it and no payment code in
it. There is no in-game currency either: nothing to collect, nothing to spend,
nothing to win and nothing to risk. Hints have no daily limit.

OFFLINE AND PRIVATE
The app has no network code at all. Nothing is collected, nothing is sent
anywhere, no advertising identifier is read, and it asks for no permissions: no
camera, no microphone, no location, no contacts, no notifications.

Recent changes:
First release.