Graphics

Simplified game pipeline

scene setup, scene and model parameter setup, rendering, post

Meshes

vertices meshed together, game engines internally triangulate for optimizations and consistency

Atomic shapes

any mesh can be decomposed into these geometric primitives with simple, convex shapes

3D primitives

common shapes for meshes to have

Transform

location/position, rotation/orientation, scale

Global/world transform

relative to world origin

Local/relative transform

relative to a parent

Quaternion

composition of vectors (W, X, Y, Z) pointing forward and rotation around it, used more often in low

Euler

(pitch, yaw, roll) used in high

OpenGL

1992, standardized graphics APIs, used by Unity and usually for simpler graphics

DirectX

Direct3D (1995) was originally a competitor to OpenGL, now used by UE4 and higher

Vulkan

(2016) from AMD Mantle (2013) meant to balance CPU and GPU and much lower level

Apple Metal

(2015) poor attempt to disrupt the game engine industry

Directional light

used for sun

Planar light

used to approximate umbrellas like in modelling

Other parts of scene setup

volumetric fog, particle generators, decals, physics, destructibility

Renderer

outputs image, shows 3D model, how model interacts with scene

Materials

encode the model’s parameters e.g. textures, colors, smoothness

Textures

images used for rendering

Traditional 3D Graphics

materials were textures with elements and needed to be preprocessed and stored, UV maps used to apply textures to 3D models

Texture maps

mostly shadows and bumps originally, baked textures onto materials, can fake effects, assist physically

UV mapping

like wrapping a piece of paper with an image around a model

UV unwrapping

flattening the model and overlaying the texture like origami

UV/texture atlas

mapping of distinct texture/UVs of separate models onto single texture/UV map to merge textures in a scene

Mathematical mapping

topology, mapping between coordinate systems

Game maps

often small levels like multiplayer maps

Diffuse map

the surface details of the model without effect of light e.g. color, texture, patterns

Material Functions

used to transform textures

Albedo

base color in Unity

Specular map

how strong the surface will shine at a certain point

Displacement map

store height information and generate depth by adding geometry when rendered

Ambient occlusion map

approximates how bright light should be shining on any specific part of a surface

Normal map

RGB channels are used to control direction of each pixel’s normal

Vertex colors

give each vertex of the triangle a color and linearly interpolate along a polygon, major limitations but cheap and simple, used for dense vertex

Global illumination

model lighting of a scene

Shaders

info about getting everything to render and display

Phong reflection model

an empirical model of the local illumination of points on a surface

Blinn-Phong model

modification to the Phong model

Interpolating

make model appear smooth around edges without geometrically smoothing

Gouraud shading

(1971) lerps between vertices, allowed rendered models to have curves with few verts

Phong shading

(1973) allows for interpolation with specularity

Incident ray

light ray

Diffuse reflections

rays that get scattered, visible details of model

Specular reflections

rays that reflect the environment, shiny

Medium

passing through material e.g. water or glass

GLSL

OpenGL shader language similar to C, used if interfacing directly

HLSL

high level shading language

Shader graphs

make shading more accessible to high level developers

PBR and material functions

PBR enables materials to be parameterized functions with realtime light response

Lightmaps

dynamic vs static/baked lighting

Camera plane

reference plane used to create image

Camera frustum

camera’s range of vision

Rasterizing

use z-buffer to determine layer that each slice of 3D scene is on, fast and default

Ray-tracing

learns pixels by shooting rays from lights, slower than rasterizing

Denoising

makes ray-tracing more feasible by filling in blanks

2D image processing speed

very fast on modern GPUs

Post-processing pass

set of effects applied after image rendered from 3D scene

Ambient occlusion

draw shadows where there is a sudden change in topology given corners and blocking objects, gives exaggerated sense of depth

Antialiasing

smooths jagged edges from limited pixels by interpolating or filtering, per-frame or temporal

Motion blur

blurs objects moving faster than framerate can keep up with, can stylize action sequences and obscure low framerate, can cause sickness in VR

Tonemapping

maps current color range to another, can fake HDR and make colors more natural

Color grading

changing color and brightness parameters for a stylistic effect

Vignette

radial effect looks like paper degradation or tunnel vision

Depth of field

defocus things outside of focal range

Post processing volume

list of parameters, can apply differently to various scene areas in Unreal 4

Post processing stack

common features like anti-aliasing and bloom in Unity 2018

OpenXR

standardizes the HMD drivers

Principle of complexity

the more complex the individual objects in a scene are, the fewer we can have

Object complexity factors

size relative to camera, vertex count, shape, collision complexity, resolution of maps

Decimation

reduce vertices and recalculation of triangles

Maps for simplification

use when material functions are unnecessary, keep high enough resolution to save RAM

Simplifying shaders and material functions

avoid unnecessary computation, share values

Level of detail

farther objects should have less detail for optimization

Physically-based Rendering

model how meshes and materials interact with GI and approximate light paths