light_params

Light Parameters

type	property	description	default
float	size	diameter of the light source (reflector or bulb)	0
float	angle	light field angle [deg], ignored on point lights	50
float	edge	soft edge coefficient, 0..1 portion of the light area along the edges where light fades to make it soft	0.5
float	intensity	light intenity (can be left 0 and use the range instead)	0
float4	color	RGB color and near-infrared component of the light emitter	float4(1,1,1,0)
float	range	desired range of light	0
float	fadeout	time to fade after turning off	0

If either intensity or range are specified alone, the other one is computed automatically. If neither one is specified, the intensity is taken from the color value, otherwise the colors are normalized. If both intensity and range are specified, the light can have shorter range to avoid leaking outside of cockpits etc.

Note: the final "intensity" of light is affected not only by intensity parameter, but also by angle and range.

Lights used in vehicles

Passing lights - used as front low beam lights and rear tail lights

Main lights - used as front high beam lights, they are brighter than passing lights

Brake lights - used when the car brakes, they are brighter than the rear tail lights

Turn lights - used as signal lights, they are activated on one side to advertise intent to turn or change lanes towards that side

Emergency lights - used as hazard lights, all turn lights used simultaneously as a hazard warning signal to warn other drivers of a vehicle parked on the road

Reverse lights - used to warn of a vehicle's rearward motion, and to provide illumination to the rear when reversing

Cabin lights - lights in cabin

Lights used in aircraft

Aircraft visibility lights

Navigation lights - to identify the aircraft direction - red light on the left wing tip, green light on the right wing tip and may have white light on the tail

Strobe lights - flashing high intensity white lights on wing tips and also on tail, they are turned on, when entering an active runway for takeoff and turned off, after landing and exiting the active runway

Beacon lights - flashing red lights on top and bottom of the fuselage, they are turned on, before the engine has started and turned off when the engines are shut down.

Pilot's visibility lights (for outside of the aircraft)

Taxi lights - high intensity lights with front direction, used during taxiing (moving on ground). They may be installed on the nose landing gear or on the wing root

Runway turn off lights - similar to taxi lights, but they illuminate the right and left side from the nose landing gear

Landing lights - high intensity lights used during takeoff and landing to illuminate the runway surface. They may be installed on the landing gear, fuselage or the wings. They are turned on before takeoff and during approach.

Wing inspection lights - installed on fuselage, they illuminate the leading edge of wings and engine pylons, to inspect them before/during flight.

Other lights

Cabin lights - lights in cabin

Logo lights - mounted on horizontal stabilizer, pointed towards the vertical stabilizer to illuminate the company logo on the tail of the aircraft

Bitmasking

Bitmasking is used for lights to manipulate individual lights (represented as bits).

Imagine, that we have 4 lights, which we can represent as 4 bits. These lights can be for example turn lights for our car, which we defined in the following way:

lightProp = {size:0.1, edge:0.8, fadeout:0, color:{x:0.4,y:0.1,z:0},range:0.004,  intensity:1 };
let turnLightOffset =
add_point_light({x:-0.71,y:2.25,z:0.63}, lightProp); 	//left front turn light (0001)
add_point_light({x:-0.64,y:-2.11,z:0.72}, lightProp); 	//left rear turn light (0010)
add_point_light({x:0.71,y:2.25,z:0.63}, lightProp); 	//right front turn light (0100)
add_point_light({x:0.64,y:-2.11,z:0.72}, lightProp); 	//right rear turn light (1000)

Now as we want to use them, for example, in function light_mask(), we need to know, which bits should be affected.

Here is representation of our 4 lights in binary, decimal and hexadecimal system, which system you use is up to you.

Decimal	Binary	Hexadecimal	Description
1	0b0001	0x1	left front turn light
2	0b0010	0x2	left rear turn light
4	0b0100	0x4	right front turn light
8	0b1000	0x8	right rear turn light

And here are the combinations, which we can use

Decimal	Binary	Hexadecimal	Description
0	0b0000	0x0	used for lights to turn off
1	0b0001	0x1	left front turn light
2	0b0010	0x2	left rear turn light
3	0b0011	0x3	left rear + left front (left side)
4	0b0100	0x4	right front turn light
5	0b0101	0x5	right front + left front (front side)
6	0b0110	0x6	right front + left rear
7	0b0111	0x7	right front + left rear + left front
8	0b1000	0x8	right rear turn light
9	0b1001	0x9	right rear + left front
10	0b1010	0xa	right rear + left rear (rear side)
11	0b1011	0xb	right rear + left rear + left front
12	0b1100	0xc	right rear + right front (right side)
13	0b1101	0xd	right rear + right front + left front
14	0b1110	0xe	right rear + right front + left rear
15	0b1111	0xf	all turn lights (emergency lights)

For turn lights, we want to activate left lights, right sides or all lights (emergency).

We can do that, by creating light mask, where we use left shift operator (<<) to shift our lights by the first turn light offset.

TurnLeftMask = 0x3<<turnLightOffset;
//Add previous left turn lights to the offset (or you can make another offset for right turn lights and use that....) 
TurnRightMask = 0x3<<(turnLightOffset + 0x2);

//When the left turn signal button was pressed, we want to activate turn lights on the left side
light_mask(TurnLeftMask, val == 1 );
//When the right turn signal button was pressed, we want to activate turn lights on the right side
light_mask(TurnRightMask, val == -1 );

or directly, by adding first light offset as 3. parameter in light_mask() function

//When the left turn signal button was pressed, we want to activate turn lights on the left side
light_mask(0x3, val == 1, turnLightOffset );
//When the right turn signal button was pressed, we want to activate turn lights on the right side
light_mask(0x3, val == -1, (turnLightOffset + 0x2) );