2D Pipeline

Question 1

All images on a computer are made up of…

Answer 1

Pixels

Question 2

The resolution of an image represents…

Answer 2

The density of points describing the image/the number of pixels per axis

Question 3

The colour of a pixel is represented as…

Answer 3

The distribution of red, green and blue that makes up the colour needed

Question 4

Given any colour, regardless of distribution of wavelengths, we can represent it as a mixture of…

Answer 4

Red, green and blue

Question 5

We can make any colour with red, green and blue because…

Answer 5

Human colour vision is based on three ‘cone’ cell types in our corneas, able to detect red, green and blue

Question 6

Alongside red, green and blue (RGB), which is a type of additive colour mixing, we can also obtain colour using…

Answer 6

Cyan, Magenta and Yellow (CMY), which is a type of subtractive colour mixing

Question 6

Subtractive colour mixing is…
Additive colour mixing is…

Answer 6

The absorption and reflection of light to move colours from their primary state towards black to reach the intended colour

The blending of light to move colours from black to their intended state

Question 7

The representation of pixel colour as either RGB or CMY is a type of…

Answer 7

Encoding

Question 8

A raster display is…

Answer 8

A rectangular array of pixels with varied intensity

Question 9

The display of a screen or bound is stored as an in-memory map called the…

Answer 9

Frame-buffer

Question 10

The order in which the frame-buffer may be read is…

Answer 10

Any. There is no restriction on how you read or write to the frame-buffer

Question 11

The frame-buffer’s contents are sent to the display hardware in a […] order for rendering.

Answer 11

Sequential, row-by-row, left-to-right (pick one)

Question 12

Pictures or scenes are represented as…

Answer 12

A set of Cartesian coordinates with infinite precision

Question 13

Raster displays are represented as…

Answer 13

A set of pixel coordinates with finite precision

Question 14

Primitives are…

Answer 14

Simple graphics that may be combined to make a bigger, more complex object (like a square, triangle, circle)

Question 15

Some examples of primitives in a 2D scene are…

Answer 15

Triangle, square, circle, polygon, line (pick two)

Question 16

Geometric primitives are…

Answer 16

Ideal mathematical objects specified by their location and dimension

Question 17

A geometric primitive triangle may be represented by its…

Answer 17

Points, lines and a bounding box

Question 18

Geometric primitives may have their […] altered. (pick two)

Answer 18

Line width, line style and colour

Question 19

An object may be called a polygon if all of its…

Answer 19

Lines are closed

Question 20

Is a triangle a polygon?

Answer 20

Yes, as it has three polylines which are closed

Question 21

Objects are constructed in […] coordinates.

Answer 21

Local

Question 22

Objects are placed in […] coordinates.

Answer 22

World

Question 23

The 2D pipeline’s Model scene consists of…

Answer 23

Constructing objects from local coordinates, then placing them in world coordinates

Question 24

The 2D pipeline's View scene consists of...

Answer 24

Clipping the scene to the window, then mapping that scene to the viewport

Question 25

The 2D pipeline's Output consists of...

Answer 25

Rasterising vectors to pixels for display, determining appearance using attributes

Question 26

In order to perform interaction, the steps we take are...

Answer 26

The 2D pipeline in reverse. Rasterise mouse location, locate primitives from that location, then induce an interaction using the location

Question 27

Rotation is performed using...

Answer 27

A rotation matrix, such that: [cos0, -sin0] [sin0, cos0]

Question 28

Scaling is performed using...

Answer 28

A scaling matrix, which is diagonal, i.e: [1, 0] [0, 1]

Question 29

Shearing is the process of...

Answer 29

Linear transformation by scaling one coordinate by the other, leaving one unchanged

Question 30

Shearing is performed by...

Answer 30

A shearing matrix, which is an identity matrix with a scaling factor applied to either the top right or bottom left unit based on whether x or y should be affected

Question 31

We can combine linear transformations by...

Answer 31

Multiplying transformations by eachother. e.g. Rotation * Scaling * x performs Scaling, then Rotation. Ergo, a full linear transformation may be expressed as a linear transformation matrix, such that A = Rotation * Scaling * Shearing, and x' = Ax.

Question 32

An affine transformation is...

Answer 32

Any linear mapping that preserves local points, straight lines and planes, but not necessarily angles or lengths

Question 33

Some examples of affine transformations are... (HINT: preserves local points but not lengths or angles) (pick 3)

Answer 33

Rotation, scaling, translation, shearing

Question 34

Combinations of affine transformations are a little more complicated because...

Answer 34

For a generic linear transformation, we can simply do f(g(x)) = R(Sx). However, for an affine transformation, we have to do f(g(x)) = R(Sx + b) + c, or RSx + Sb + c.

Question 35

Non-commutative is a term we would use to describe...

Answer 35

Matrix multiplication

Question 36

We can solve the issue of combining affine combinations by...

Answer 36

Representing the combination as an extended matrix with (x+1), (y+1) shape, such that the first (x,y) are the linear transformations, and the last (x:x+1, 0:y+1) are the translations

Question 37

Rotation, scaling, shearing and translations commute with...

Answer 37

Each other, and ONLY each other

Question 38

One transformation is said to only commute with itself in 2D, which is...

Answer 38

Rotation

Question 39

The steps for rotating about a point are...

Answer 39

Translating the object back to the origin, rotating it about the origin, then translating it back