World 9

Looks

Why one screenshot reads in a blink and another reads as mud: the words for art direction, light, colour, pixels and animation.

A game's art is a set of decisions long before it is a set of pictures, and most of those decisions have names. Without the names, feedback stops at "make it pop" or "it looks cheap". With them you can ask for a clearer silhouette, two more value steps, less bloom or animation on twos, and get the thing you meant.

Art directionThe set of decisions that makes every picture in a game look as if it belongs to the same game: palette, shapes, lighting, level of detail, how things move. An art director writes those rules and holds everyone to them.
StylisationDeliberately leaving out and exaggerating parts of reality so that what remains says more. A stylised tree is not a worse tree; it is a choice about which few things make a tree.
ReadabilityHow quickly a player can tell what they are looking at and what it means for them: what can hurt me, what can I touch, where can I stand. Artists say a thing "reads" when it is understood in a glance.
SilhouetteThe outline of a character or object, filled in solid. The silhouette test asks whether you can still tell who it is with all colour and interior detail gone.
Value structureThe pattern of light and dark in a picture, ignoring colour. Value means how bright a colour is. The squint test is the old painter's check: narrow your eyes until detail goes, and see whether the picture still holds together.
Focal pointThe one place the eye lands first. You make it with the strongest contrast, the only saturated colour, an isolated shape, or lines that point at it.
Shape languageBuilding a design out of one family of simple shapes so that it carries a meaning before any detail. Circles tend to read as friendly, squares as sturdy, and triangles as dangerous or quick.
PaletteThe fixed set of colours a game, a level or a character is allowed to use. Old hardware forced a small one; artists now often choose one anyway.
Colour harmonyChoosing colours by where they sit on the colour wheel. Neighbours (analogous) feel calm, opposites (complementary) feel tense and bright, and three spaced evenly (triadic) feel playful.
Colour scriptThe whole story laid out as a strip of small paintings, one per beat, so you can read its emotional arc as colour before anything is built. It answers: what does each part of this feel like, and how does it change?
Foreground framingPlacing dark shapes close to the camera, such as branches, rocks or a doorway, around the edge of the view so they frame what matters.
Atmospheric perspectiveFar things look paler, bluer and lower in contrast, because there is more air between you and them. Painters have used this for centuries to make a flat surface look deep.
ParallaxBackground layers move slower than the foreground as the camera moves, the same way that fence posts rush past a train window while hills barely shift. It fakes depth on a flat screen.
Pixel artArt made at a low resolution with every pixel placed on purpose, then shown enlarged with hard edges. Each pixel is a decision, which is what separates it from a shrunken image.
Palette swapThe same image data shown with a different set of colours. The picture stores numbers that point into a palette, so changing the palette recolours everything at once and costs no extra art.
DitheringFaking colours you do not have by mixing dots of the ones you do. From a distance, a checkerboard of black and white looks grey, so a smooth gradient survives a tiny palette.
SpriteA 2D image drawn into the game at some position, usually a character or object. A sprite sheet is one image holding all its frames; playing the animation means showing a different rectangle of it each moment.
TilesetA set of small square images that fit together edge to edge, used to build big levels from a small amount of art. Autotiling picks the right edge or corner piece for you by checking each tile's neighbours.
Texture atlasOne big image with many smaller images packed into it. Switching images is slow for a graphics card, so if everything lives in a single image the game can draw it all in one go.
Low polyModels built from few triangles, with the facets left showing. Once a hardware limit, it is now often a chosen style, because each flat face catches light as a single colour.
PBRShading materials by rules of real light, usually described with two main numbers: how rough a surface is and whether it is metal. Because the material is described and not painted, it looks right under any light.
Normal mapA texture that stores which way the surface faces at every pixel, as a colour. Lighting reads it, so a flat wall gets the shading of bricks and cracks while the geometry stays flat.
Cel shadingShading in a few flat steps of colour instead of a smooth gradient, often with an ink outline, so a 3D model looks like a hand-painted animation cel.
Rim lightA thin line of light along the edge of a shape, as if something bright stands behind it. In games it is often calculated: the more a surface turns away from you, the brighter it gets.
Ambient occlusionSoft darkening where surfaces meet: in creases, corners and under objects, where less of the surrounding light can reach. It is a shadow with no particular light causing it.
BloomBright parts of the picture bleed soft light into the pixels around them, the way light scatters in your eye or in a camera lens. It works by copying the brightest pixels, blurring them, and adding them back.
Colour gradingShifting all the colours of the finished picture to set a mood, as a last step. A LUT, or lookup table, stores the shift as a small cube of colours: each input colour simply looks up its output.
MipmapA stack of smaller, already blurred copies of each texture, and the graphics card picks the size that fits how far away the surface is. "Mip" comes from the Latin multum in parvo, much in a small space. Lance Williams described it in 1983.
SkyboxA giant picture of the distant world wrapped around the camera, usually on the inside of a cube, and drawn behind everything else. It moves with you, so you can never get closer to it, which is how it seems infinitely far away.
BillboardingA flat picture in a 3D world that keeps turning to face the camera, so you never catch it edge-on. Trees, grass, particles and old-style enemies are often done this way.
The twelve principles of animationTwelve rules for making drawings seem alive, worked out by Disney's animators and set down by Frank Thomas and Ollie Johnston in their 1981 book The Illusion of Life. They are still how animators talk about motion.
Timing and spacingTiming is how many frames a move takes. Spacing is how far it travels between each of those frames. Same timing with different spacing gives very different motion.
Pose to poseDrawing the most important poses first, then filling in the frames between them. Its opposite is straight ahead, drawing each frame after the last from start to finish.
Animating on twosShowing each drawing for two frames of a 24-frame second, so there are 12 new drawings a second. "On ones" means a new drawing every frame, and "on threes" every third. The holds are a choice, not a slowdown.
Smear framesOne or two distorted drawings, shown so briefly you never quite see them, that stretch an object along its path during a very fast move. It is the hand-drawn version of motion blur.
Skeletal animationTwo ways to make a character move. Frame by frame means a new drawing for each pose. Skeletal means one drawing (or model) attached to bones, with the computer moving the bones.
RiggingBuilding the skeleton and the controls that move a character. With forward kinematics you rotate each joint in turn, from the shoulder down. With inverse kinematics you place the hand, and the solver works out the joints.
Blend treeA small graph that mixes animations by a number from the game. Feed in speed and it returns, say, 30% walk and 70% run, averaged joint by joint and kept in step, so there is no separate clip for every speed.
Root motionLetting the animation decide how far the character moves. The animator moves the whole body in the clip, and the game follows it. Its opposite is in-place animation, where code moves the character and the clip marches on the spot.