Glossary

Terms that show up across the book and across game development generally.

A

Alpha Blending Rendering transparent surfaces by mixing the source color with the destination color, weighted by alpha.

Alpha Cutoff A threshold for alpha testing. Pixels with alpha below the threshold are discarded entirely.

Ambient Light A constant, directionless light applied to every surface. Stands in for indirect illumination.

Ambient Occlusion (AO) A darkening of creases and corners where ambient light would be blocked. See SSAO.

Animation Blending Interpolating transforms between two animations to produce a smooth transition.

Animation Clip A named animation like "walk", "run", or "idle" made of keyframed transforms.

Aspect Ratio Viewport width divided by viewport height. 16:9 is 1.777.

B

Billboard A flat quad oriented to face the camera each frame. Used for particles and distant objects.

Bind Pose The default pose of a skinned mesh before any animation is applied.

Bloom A post-processing effect that adds a glow around bright pixels.

Bone A joint in a skeletal hierarchy. Also called a joint.

C

Cascaded Shadow Maps (CSM) Several shadow maps at different resolutions covering different ranges of view distance.

CCD (Continuous Collision Detection) A physics technique that prevents fast-moving objects from passing through thin surfaces between simulation steps.

Character Controller A kinematic physics body specialized for player movement, with handling for stairs and slopes.

Collider A simplified shape used for collision detection. Box, sphere, capsule, and so on.

Component Data attached to an entity in an ECS. Holds state, never logic.

Culling Skipping objects during rendering because they are outside the view or hidden by other geometry.

D

Delta Time (dt) The time between the previous frame and this one. Multiplying by dt keeps motion the same speed at any frame rate.

Depth Buffer (Z-Buffer) A texture storing the distance of each pixel from the camera. Used to decide which surface is closest.

Diffuse The base color of a surface, independent of view angle.

Dynamic Body A physics body that responds to forces, gravity, and collisions.

E

ECS (Entity Component System) An architecture where entities are IDs, components are data, and systems are functions over the components.

Emission/Emissive Light a surface produces on its own, independent of any external light source.

Entity An identifier that groups components together. Holds no data on its own.

Euler Angles Rotation expressed as three angles (pitch, yaw, roll). Subject to gimbal lock.

Exposure A brightness multiplier that mimics camera exposure settings.

F

Far Plane The maximum distance from the camera at which geometry is rendered. Anything past it is clipped.

Field of View (FOV) The angle of the visible area. Most games sit between 60 and 90 degrees.

Forward Rendering Rendering each object fully in one pass. Direct but expensive when many lights affect each object.

Frame One full update plus render cycle.

Frustum The truncated pyramid of space visible to a perspective camera.

G

G-Buffer A set of textures holding geometry data (normals, depth, albedo) used by deferred rendering.

Gimbal Lock Losing a rotation axis when two of three Euler axes line up. Quaternions sidestep the problem.

glTF/GLB A standard 3D model format. glTF is JSON with a separate binary blob. GLB packs both into a single file.

Global Transform The world-space transform after every parent's transform has been applied.

H

HDR (High Dynamic Range) Color values outside the 0 to 1 range. Lets lighting math go above white before tonemapping brings it back down.

Heightfield A 2D grid of height values representing terrain or any heightmap-shaped surface.

Hierarchy A parent-child tree of entities. Each child's transform is expressed relative to its parent.

I

Index Buffer A list of vertex indices that defines the triangles of a mesh. Lets a vertex be reused in many triangles.

Instancing Drawing many copies of the same mesh in a single draw call, varying per-instance data like transform.

Interpolation Blending between two values. Linear interpolation (lerp) is the simplest form.

J

Joint A constraint between two physics bodies that limits their relative motion.

K

Keyframe A value at a specific time in an animation. Values between keyframes are interpolated.

Kinematic Body A physics body moved by code. Pushes dynamic bodies but is not pushed back.

L

LDR (Low Dynamic Range) The standard 0 to 1 color range that displays understand.

Lerp (Linear Interpolation) result = a + (b - a) * t for t between 0 and 1.

LOD (Level of Detail) Lower-detail meshes used for objects far from the camera.

Local Transform A transform expressed relative to the parent entity, or world space when there is no parent.

M

Material The data that describes how a surface looks. Color, roughness, metallic, textures, and so on.

Mesh Geometry stored as vertices and indices that form triangles.

Metallic A PBR parameter that goes between dielectric (0) and metal (1).

Mipmaps Smaller pre-filtered copies of a texture used when sampling at distance.

Morph Targets Per-vertex offsets that blend a mesh between shapes. Used for facial animation. Also called blend shapes.

N

NavMesh (Navigation Mesh) Simplified geometry that represents walkable areas for AI pathfinding.

Near Plane The minimum distance from the camera at which geometry is rendered. Closer geometry is clipped.

Normal Map A texture that encodes per-pixel surface direction. Fakes geometric detail without adding triangles.

O

Occlusion One object blocking another from being seen or lit.

Orthographic Projection A parallel projection. Distance does not change apparent size.

P

PBR (Physically Based Rendering) A material model derived from real-world light behavior. Produces consistent results across lighting setups.

Perspective Projection A projection in which distant objects appear smaller. Matches the way human vision works.

Pitch Rotation around the X axis. Looking up and down.

Point Light A light emitting outward equally in every direction from a point.

Prefab A pre-configured entity template that can be instantiated as many times as needed.

Q

Quaternion A four-component number that represents a rotation without gimbal lock. Interpolates smoothly.

Query A request for all entities that have a specific set of components.

R

Raycast Tracing a ray through space to find the first surface it hits.

Render Graph A declarative description of rendering passes and their dependencies.

Render Pass A single stage of rendering, such as a shadow pass, the main color pass, or a post-processing pass.

Rigid Body A non-deformable physics object. Can be dynamic, kinematic, or static.

Roll Rotation around the Z axis. Tilting sideways.

Roughness A PBR parameter that scatters specular reflection. 0 is a mirror. 1 is fully diffuse.

S

Skinning Deforming mesh vertices according to bone transforms. The mechanism behind skeletal animation.

Skybox A cubemap texture that surrounds the scene and stands in for the distant environment.

Slerp (Spherical Linear Interpolation) Interpolation between two quaternions at constant angular speed.

Specular Mirror-like reflection of light. Strength depends on view angle.

Spot Light A light that emits in a cone, like a flashlight.

SSAO (Screen-Space Ambient Occlusion) An approximation of ambient occlusion computed from the depth buffer in screen space.

Static Body A physics body that never moves. Used for floors, walls, and terrain.

System A function that operates on entities matching a given component query.

T

Tessellation Subdividing geometry into more triangles, usually at runtime on the GPU.

Texture A 2D image sampled across a 3D surface.

Tonemapping Mapping HDR values down to the LDR range a display can show.

Transform The position, rotation, and scale of an object in space.

Transparency See Alpha Blending.

Trimesh (Triangle Mesh) A collision shape that uses the actual mesh triangles. Accurate but costly.

U

UV Coordinates 2D texture coordinates that map texture pixels to mesh vertices.

Uniform A shader constant that holds the same value for every vertex or pixel in a draw call.

V

Vertex A point in 3D space carrying position, normal, texture coordinates, and similar attributes.

Vertex Buffer GPU memory that holds vertex data.

Vignette A post-processing effect that darkens the edges of the screen.

Vulkan A low-level graphics API. wgpu uses it on Windows and Linux.

W

WebGPU A graphics API designed for browsers. wgpu uses it for web targets and exposes a similar shape across native APIs.

World Space The single global coordinate system shared by every entity. Compare local space.

wgpu A Rust graphics library that gives a single API across Vulkan, DX12, Metal, and WebGPU.

Y

Yaw Rotation around the Y axis. Looking left and right.

Z

Z-Buffer See Depth Buffer.

Z-Fighting Flickering between two surfaces at nearly the same depth, caused by precision loss in the depth buffer.