Light and shadow

Light shows the player what is there, how far away it is and what matters. Shadow is just as important: it groups shapes, hides what is unimportant and gives the light something to contrast with. This page covers the art of light and shadow. The engine side (light types, units, baking, shadow maps) lives in real-time lighting and the pages linked from it.

The Level Design Book sums up the job of game lighting: it gives the scene depth and helps players judge distances and tell shapes apart, and it should start "early in the level design process, before a proper art pass" (The Level Design Book: Lighting).

#How light reveals form

Drawing teachers describe light on a form in a small set of zones. Stan Prokopenko's version (Proko: Shading Light and Form – Basics):

• Light and shadow are the "two main zones".
• Terminator: "The edge where the form transitions from light to shadow".
• Halftone: planes "partially hit by the direct light", getting lighter as they turn towards it.
• Core shadow: "a darker plane that defines the edge of the shadow", just past the terminator.
• Reflected light: "Light bounces off objects in the environment and is reflected back into the shadows."
• Cast shadow: "caused by one form blocking the light from hitting another form."
• Occlusion shadow: the darkening in crevices and contact points that gets darker as it goes deeper.
• Highlight: "a reflection of the light source", which moves with the viewer.

These terms map neatly onto a renderer. Direct light gives the light zone, halftone and terminator. global illumination supplies reflected light. Shadow maps draw cast shadows (shadows and virtual shadow maps), and ambient occlusion approximates occlusion shadows. Highlights come from roughness and specular response in physically based rendering.

The most important rule is to keep the light family lighter than the shadow family. If reflected light in the shadow is brighter than the halftone in the light, the form flattens and reads as confusing. See value.

#Key, fill and rim

Film and photography describe lights by role. The Level Design Book's summary of three-point lighting (The Level Design Book: Three point lighting):

• Key light: "the main dominant light source that illuminates most of the subject or area". In games, often the sun or a strong spotlight.
• Fill light: softer light that lifts the shadows, usually ambient light plus dim, invisible lights in games.
• Rim (back) light: separates the subject from the background by lighting its edges.

Betancourt's version for game scenes: "The key light is master" (80 Level: Learning Lighting for Video Games). His advice when a scene gets messy is "deleting all lights and starting again with the key", because "too many lights being used in a scene results in muddy, confusing direction" (80 Level: Learning Lighting for Video Games).

#Light as composition

Light is one of the main tools for steering attention. Mateusz Piaskiewicz's guideline is: "The most important objects should be well lit, the rest of the composition's elements should be covered with shadows" (Game Developer: Composition in Level Design). He points to BioShock Infinite, where blue light makes a silhouette readable, and Call of Duty: Black Ops 2, where colour and light guide the player down a corridor (Game Developer: Composition in Level Design).

The Level Design Book makes the same point for flow: "brightly lit doorways help players understand the flow of the room", and "Big important exits should have more important looking lighting" (The Level Design Book: Lighting). Its D6 focal frame uses two matching lights such as torches or sconces to mark an entrance or exit (The Level Design Book: D6 lighting). See focal point, leading lines and wayfinding.

#Shadow shapes

Shadows are shapes in their own right. Betancourt talks about "pushing for interesting shadow shapes to get the most out of it" and "avoiding flat shapes", because "Lighting builds depth" (80 Level: Learning Lighting for Video Games). A window that throws a patterned shadow across a floor, or foliage that breaks up a sunlit wall, adds interest without adding geometry.

Shadow also controls what the player notices. Areas you want ignored can sit in shadow; the eye will skip them. The opposite risk is shadow that hides gameplay. Betancourt stresses "making sure enemies and cover in an area remain distinct" (80 Level: Learning Lighting for Video Games). The Level Design Book adds that a "strong spotlight draws attention to enemy silhouettes" (The Level Design Book: Lighting).

#Mood, time and colour

Light sets the emotional tone. Sobotta writes: "Lighting really does set the tone, mood and drive the eye through a piece of art" (CGSociety: How to Create a Stunning Portfolio with Jared…). Betancourt describes coordinating "color and mood via sun, sky, shadow, and exposure", starting from "a really good reference from a photograph or a film" (80 Level: Learning Lighting for Video Games).

Art director John Sweeney says of The Last of Us Part II: "Color and lighting are probably the things I spent the most time on", and credits its indirect lighting to "a lot of artists and programmers collaborating" (Cook & Becker: Art directing The Last of Us Part II). The team also built dynamic ambient shadowing for characters near objects or moving from bright exteriors into dark rooms (Cook & Becker: Art directing The Last of Us Part II). On large productions, the look of light is a shared art and engineering problem. The colour side is covered in colour for environments.

#A lighting process

The Level Design Book suggests four passes (The Level Design Book: Lighting):

1. Global: sun, sky and ambient; the overall value and colour of the space.
2. Wayfinding and critical path: light the exits and the route. See critical path.
3. Gameplay: foreshadow encounters, light cover and enemies, highlight puzzle elements.
4. Detail and mood: accents and atmosphere, without undoing earlier passes, since "if you tweak it too much you might destroy the effect from a previous pass".

This order puts readability before beauty, which matches the professional advice above.

#Related pages

value · colour for environments · real-time lighting · global illumination · ambient occlusion · exposure and post-processing · fog and atmosphere · focal point · composition · wayfinding

#Further reading and watching