Class TextModeCRTBeam

Switches the beam simulator on and off for every CRT picture at once and holds its shared clock. The simulator brings back the motion clarity of a CRT on displays at 120 Hz and above.

Inheritance

object

TextModeCRTBeam

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: Scylla.TextMode.CRT

Assembly: ScyllaTextMode.CRT.dll

Syntax

public static class TextModeCRTBeam

Remarks

A real CRT lights only the part of the picture the electron beam is drawing at that moment, and the phosphor fades quickly afterwards. That is why moving objects look sharp on a CRT and smeared on an LCD, which holds every frame for the whole refresh. The simulator copies this on a fast display: the display refreshes several times for every simulated CRT frame, and each refresh shows only the band of the picture the beam would have reached.

The simulator counts display refreshes, not game frames. With vSync on, every Unity frame is one refresh, so the count advances by one per frame. A frame that takes longer advances it by the refreshes it spanned, which keeps the beam in step with the display; the skipped refreshes are counted in MissedRefreshes and show as flicker. The math lives in CRTBeam and the counting in CRTBeamClock.

All state is static and shared. The settings come from the TextMode configuration the first time a CRT picture asks for them. A setting that game code assigns keeps its value when the configuration is applied, and ApplySettings(CRTSettings) replaces all of them. Every setting returns to its default when a play session starts, so nothing carries over when domain reload is off.

The simulator depends on the display, not on a picture's look, so it is one switch for every TextMode view with a CRT and every camera effect. The in-world monitor never uses it.

Photosensitivity: the simulator makes the picture flicker at the CRT rate, 60 Hz by default, like a real CRT. It is off by default, and Reduce Motion in the TextMode configuration keeps it off.

It needs vSync on with one refresh per frame (QualitySettings.vSyncCount = 1), a display at twice the CRT rate or more, and variable refresh rate off. Frames the game misses move the beam on and show as flicker. When the game runs much faster than the display refreshes, which means vSync is not in effect, the simulator waits and the picture stays as it is without it; see OutpacesDisplay(double, double). In the Editor, the Game view only follows vSync with VSync turned on in its menu. It only runs in Play mode.

The following example switches the simulator on for a 240 Hz display and reads its state.

QualitySettings.vSyncCount = 1;
TextModeCRTBeam.CRTRate = 60f;
TextModeCRTBeam.ScanDirection = CRTBeamScanDirection.TopToBottom;
TextModeCRTBeam.Enabled = true;
var status = TextModeCRTBeam.GetStatus();
if (status.Enabled && !status.Active)
{
Debug.Log("Beam simulator is not running: " + status.Reason);
}

Fields

DEFAULT_CRT_RATE

Default simulated CRT refresh rate in hertz, 60. It is also the value CRTRate falls back to when it is set to NaN.

Declaration

public const float DEFAULT_CRT_RATE = 60

Field Value

Type	Description
float

Properties

AntiRetention

Gets or sets whether an even number of refreshes per CRT frame drifts slowly, which keeps an LCD from retaining a pattern. Can be turned off on OLED displays.

Declaration

public static bool AntiRetention { get; set; }

Property Value

Type	Description
bool

CRTRate

Gets or sets the simulated CRT's refresh rate in hertz. The display needs at least twice this rate. The value is clamped to 24 through 240 Hz, and NaN gives DEFAULT_CRT_RATE.

Declaration

public static float CRTRate { get; set; }

Property Value

Type	Description
float

DisplayRate

Gets the display refresh rate in hertz the simulator counts with.

Declaration

public static double DisplayRate { get; }

Property Value

Type	Description
double

EffectiveGain

Gets the gain in use: Gain, or the default for the display rate when it is 0. The result is 0.5 below 200 Hz and 0.7 from 200 Hz upward; see DefaultGain(double).

Declaration

public static float EffectiveGain { get; }

Property Value

Type	Description
float

Enabled

Gets or sets whether the beam simulator is wanted. It only runs when the display is fast enough, vSync is in effect, Reduce Motion is off and the game is playing; see IsActive. A value set from code is kept: when the TextMode configuration is applied, every setting code has set since the last time it was applied keeps its value, and only the others are taken from the configuration. ApplySettings(CRTSettings) overrides all of them. False until code or the configuration turns it on.

Declaration

public static bool Enabled { get; set; }

Property Value

Type	Description
bool

Frames

Gets the display refreshes per CRT frame, or 0 when the display is too slow.

Declaration

public static float Frames { get; }

Property Value

Type	Description
float

Gain

Gets or sets the share of the picture's brightness the tube gives off on average, from 0 to 1. 0 picks 0.5 below 200 Hz and 0.7 above. Higher is brighter with more motion blur.

Declaration

public static float Gain { get; set; }

Property Value

Type	Description
float

IsActive

Gets whether the simulator runs this frame. It is false when no CRT ticked the simulator in the previous frame, because the status then no longer describes what is on screen.

Declaration

public static bool IsActive { get; }

Property Value

Type	Description
bool

Remarks

The value only changes when a CRT picture draws, so it stays false while no CRT view or camera effect is on screen, even when Enabled is true.

MissedRefreshes

Gets the number of refreshes that passed without a frame since the simulator last went from inactive to active. A count that keeps rising means the game does not keep up with the display.

Declaration

public static long MissedRefreshes { get; }

Property Value

Type	Description
long

RefreshRateOverride

Gets or sets a display refresh rate in hertz to use instead of the one the display reports, for displays that report it wrongly. 0 uses the reported rate. Values above 1000 are clamped to 1000; NaN and values of 0 or less give 0.

Declaration

public static float RefreshRateOverride { get; set; }

Property Value

Type	Description
float

ScanDirection

Gets or sets the direction in which the beam sweeps the tube. The default is TopToBottom.

Declaration

public static CRTBeamScanDirection ScanDirection { get; set; }

Property Value

Type	Description
CRTBeamScanDirection

SlowMotionDivisor

Gets or sets how many frames each simulated refresh lasts, for watching the sweep on a slow display. 1, the default, runs at the real rate. A development aid only.

Declaration

public static int SlowMotionDivisor { get; set; }

Property Value

Type	Description
int

Methods

ApplySettings(CRTSettings)

Copies the beam simulator's settings from a TextMode configuration. The configuration of the running TextMode module is applied automatically when the simulator first looks at it, without touching settings game code has set; call this to apply every setting, for example settings a player changed at runtime.

Declaration

public static void ApplySettings(CRTSettings settings)

Parameters

Type	Name	Description
CRTSettings	settings	The CRT settings of a TextMode configuration.

GetStatus()

Returns a snapshot of the simulator's state.

Declaration

public static CRTBeamStatus GetStatus()

Returns

Type	Description
CRTBeamStatus	The current state.

ResolveDisplayRate()

Returns the display refresh rate the simulator uses: RefreshRateOverride, or the rate the display reports.

Declaration

public static double ResolveDisplayRate()

Returns

Type	Description
double	The refresh rate in hertz, 0 when it is not known.