Just like the real world, in Unity

we use lights to illuminate our scenes.

Without lights nothing would be visible

to the cameras in our scene.

Broadly there are two types of lighting in Unity

dynamic and baked lighting.

Dynamic lighting is calculated in

real time while our game is running.

This can be achieved simply by adding lights to our scene.

Baked lighting is calculated offline

and saved to a texture.

These lighting texture maps are then applied

to the baked objects in the scene

for improved performance.

For more information on baked and dynamic

lighting see the lesson linked below.

To light our scene we use the Light component.

Like all components in Unity

the light component is attached to a game object.

We can move the light within our scene

using the game objects transform.

The light component has four different types of lights.

The Point Light, the Directional Light,

the Spot Light and for baked

lighting only, the Area Light.

Each of these types behave completely differently

in the way they effect the look of our game.

The point light behaves like a bare light bulb.

The point light illuminates objects in the scene

based on the light's position in the scene.

Rotation has no influence on the light

as this light shines equally

in all directions.

The directional light behaves like the sun.

Directional lights effect all the objects in the scene

lighting them based on the direction of the light

set by the game object's rotation.

Position in the scene is irrelevant.

Spot lights behave like a flashlight

or headlamps on a car.

They point in a direction based

on their transform's rotation

and illuminate all objects within a cone.

So spot lights respond to both

rotation and position.

Area lights only work when baking a light map.

Area lights shine in all directions to

one side of a rectangular plane.

In addition to these four main types of lights

there are two other items that can

influence the lighting in the scene.

Ambient light and emissive materials.

Ambient light controls global

non directional lighting in the scene.

Ambient light works with both dynamic

and baked lighting.

For complete control set the

ambient light to black

and use only the lighting in the scene.

Emissive materials are created by

setting the emission property in an

appropriate self-illuminating shader.

Emissive materials work only with baked lighting.

For more information see the lessons link below.

There are several properties that let us

customise the light.

Range determines how far a light is

emitted from the centre of the game object

holding the light component.

Range only works with point and spot lights.

When we have spot selected as our light type

we also have access to the

spot angle property.

Spot angle determines the angle of the cone

used by the spot light in degrees.

Colour will control the colour of the light.

Note the scene gizmo colour will change

to match the colour property.

Intensity controls the brightness of the light

and this is independent of range.

When trying to light a scene, a combination

of all of these properties are needed

to create effective lighting.

Our lights may appear brighter as we

increase both intensity and range.

But they both have different behaviours

in the way that they light our scene.

As well as simple illumination

lights can also use a number of effects.

Shadows, flares, halos

and something called a Cookie.

A cookie acts like a virtual mask

or flag in front of the light

to create a patterned shadow.

Cookies use the alpha channel of a texture

to give the light a projected shadow pattern.

Cookies must be a 2D texture

when working with spot and directional lights.

Cookies must be a cube map

when using a point light.

This makes sense when you think about

the fact that both spot and directional lights

are shining in one direction

and point lights are shining in all directions.

When using directional lights

there is an option to change the cookie's size,

scaling the pattern in the scene.

Cookies do not work with area lights.

When using baked lighting cookies only work

with spot lights and are ignored

for baked point lights and baked directional lights.

Shadows.

There are two types of shadows available

when casting shadows from a light.

Hard and Soft shadows.

Hard shadows are the most efficient.

Soft shadows are often more convincing.

But they're most expensive to render.

When rendering shadows there are several options.

Strength sets the value of the

darkness of the shadow.

Adjust this value until the shadow seems

correct in the scene.

Full strength, or the value of 1

is often too strong.

Resolution is simply a quality setting.

By default a light will use the value

you set in quality settings.

These values can be overridden here

on a per light basis.

For more information see the lesson on

quality settings.

Bias controls an offset value

to optimise shadow rendering

from any given light.

Bias is a setting that effects how far

from objects the shadows will start.

Values that are too low will produce artefacts,

but values that are too high will mean

that the objects appear to be hovering.

When using directional lights with soft shadows

there are two additional settings.

Softness and softness fade.

The softness is how harsh

the lines of the shadow will be

and the softness fade is a measure of

how far from the camera

the soft shadows are drawn.

For more information please see the

documentation on lights linked below.

Draw Halo will draw the default

scene halo around the light.

Halos respond to both the range

and intensity of the light.

Details for the default halo can be

set in the scene's render settings.

To override the default halo

this setting should be left off

and an individual halo component

should be used instead.

A flare is similar to a halo but

imitates a bright light source

seen through optical glass.

When a flare asset is loaded in to the flare slot

the light will render using a lens flare.

Flares only respond to the intensity of the light.

A lens flare component can be attached

directly to the game object

but then the flare property on the light

should remain empty or there will be

two flares rendered on the light.

A flare layer component must be attached

to a camera for that camera

to render a flare element.

Render Mode.

There are two different methods

of rendering dynamic lights

using vertex lighting

and using per pixel lighting.

Vertex lighting is usually the fastest

and calculates the scene's lighting

at the vertices of an objects mesh.

The lighting is then interpolated

over the surface of the mesh.

Per pixel lighting is calculated at every screen pixel

which is more expensive.

While pixel lighting is slower to render it does

allow for some effects that are not possible

with vertex lighting.

Normal mapping, light cookies and real time

shadows are only rendered for pixel lights.

Spot light shapes and specular highlights

are much better when rendered

in pixel mode as well.

Lights have a big impact on rendering speed.

The number of pixel lights can be limited

in the quality settings by

using the pixel light count property.

When you are in the forward rendering path

render mode gives explicit control

over whether a light should be rendered

as a vertex or pixel light.

Important will force the light to be

rendered per pixel and not important

will force the light to be rendered

in a faster mode using per vertex

or spherical harmonics.

For more information on render mode and

render path see the documentation link below.