psyqo::HelixSelector Class Reference

A helix selector, seen down its own axis. More...

#include <psyqo/helix-selector.hh>

Classes
struct	Config
struct	Cursor
	The cursor marker, as a triangle you can draw directly. More...
struct	Event
struct	Slot
	One visible item. More...

Public Member Functions
void	setup (unsigned itemCount, const Config &config)
void	setOnEvent (eastl::function< void(Event)> &&callback)
void	setStickAngle (Angle a)
	Crank by an absolute stick angle.
void	step (int32_t items)
	Crank by whole items. This is the d-pad adapter.
void	activate ()
	Your confirm button's rising edge.
void	update (const Trig<> &trig)
	Settle one frame and rebuild the visible slots.
unsigned	currentIndex () const
unsigned	visibleCount () const
const Slot &	slot (unsigned n) const
	Slot 0 is the furthest from the camera. Draw them in order.
const Cursor &	cursor () const
	Where to draw the cursor marker, just inside the ring at the cursor angle.
Angle	cursorAngle () const
	The cursor's current angle, if you want to orient the marker you draw.

Static Public Attributes
static constexpr unsigned	c_maxSlots = 48

Detailed Description

A helix selector, seen down its own axis.

Items are laid out along a helix wrapped around a cylinder, and the camera looks straight down the helix axis, so the screen shows a spiral of annular sectors.

EVERY ITEM OWNS A FIXED SPOKE. Item i sits at angle i * 2pi / itemsPerTurn and never leaves it. What the crank moves is the CURSOR, which sweeps around the circle; items slide IN AND OUT along their own spokes as it approaches or passes them. So this is a dial, not a carousel: a is always in the same place on screen, and the user gets muscle memory for free.

It follows that item i and item i + itemsPerTurn share a spoke exactly, at different radii. That is the far-side doubling that shows what is coming, and it falls out of the geometry rather than being tuned in.

It also means the analog adapter is ABSOLUTE: the stick angle IS the cursor angle. Only the lap needs unwrapping, which setStickAngle does for you.

This class owns the geometry and the selection state and nothing else. It has no idea what a glyph is, what a character is, or that capital letters exist. It hands back quad corners plus a centre point per visible item and reports what got selected or activated; drawing, atlases, casing, text buffers and what "enter" means are all yours.

The helix is infinite and the item list is CYCLIC on it: the item at helix offset d is (cursor + d) mod itemCount, so cranking never hits an end, and one turn out from the first item is whatever the atlas has last.

Member Function Documentation

activate()

void psyqo::HelixSelector::activate

(

)

Your confirm button's rising edge.

If the helix is still settling this snaps it to the target first and then fires, so a confirm is never swallowed mid-animation.

currentIndex()

unsigned psyqo::HelixSelector::currentIndex ( ) const

inline

cursor()

const Cursor & psyqo::HelixSelector::cursor ( ) const

inline

Where to draw the cursor marker, just inside the ring at the cursor angle.

cursorAngle()

Angle psyqo::HelixSelector::cursorAngle ( ) const

inline

The cursor's current angle, if you want to orient the marker you draw.

setOnEvent()

void psyqo::HelixSelector::setOnEvent ( eastl::function< void(Event)> &&  callback )

inline

setStickAngle()

void psyqo::HelixSelector::setStickAngle

(

Angle

a

)

Crank by an absolute stick angle.

Feed this the raw stick direction every frame the stick is deflected enough to mean something, and simply stop calling it when it re-centres; the cursor stays where it was. The stick angle IS the cursor angle, so pointing somewhere new puts the cursor there directly. The only thing accumulated is the LAP: crossing the +/-pi seam moves you one turn along the helix rather than jumping the cursor to the far side of the dial.

setup()

void psyqo::HelixSelector::setup	(	unsigned	itemCount,
		const Config &	config
	)

slot()

const Slot & psyqo::HelixSelector::slot ( unsigned  n ) const

inline

Slot 0 is the furthest from the camera. Draw them in order.

step()

void psyqo::HelixSelector::step ( int32_t  items )

inline

Crank by whole items. This is the d-pad adapter.

update()

void psyqo::HelixSelector::update

(

const Trig<> &

trig

)

Settle one frame and rebuild the visible slots.

visibleCount()

unsigned psyqo::HelixSelector::visibleCount ( ) const

inline

Member Data Documentation

c_maxSlots

constexpr unsigned psyqo::HelixSelector::c_maxSlots = 48

staticconstexpr

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The documentation for this class was generated from the following files:

• psyqo/helix-selector.hh
• psyqo/src/helix-selector.cpp