## 3D shapes

# Creative Computing

## 3D: shapes

### Marco Gillies and Mick Grierson

# Overview and aims

By the end of the lecture you will be able to:

- Describe different types of 3D graphics software and how they are used
- Describe the mathematical representation of 3D space by coordinate systems
- Explain how 3D shapes are represented using polygons
- Model simple 3D shapes in blender

# Examples

# Overview and aims

By the end of the lecture you will be able to:

- Describe different types of 3D graphics software and how they are used
- Describe the mathematical representation of 3D space by coordinate systems
- Explain how 3D shapes are represented using polygons
- Model simple 3D shapes in blender

## Software

- Modelling and animation software
- Real time graphics/games engines
- Low level graphics libraries

## Hardware

## Modelling/Animation Software

Maya

3DStudio Max

Blender

If you are making a 3D film this is all you will need.

## 3D/Game engines

Unreal

Source

Unity

Ogre

They are used for games but also other real time 3D applications.

Typically you would create content in a modelling tool like Blender and then

import it to your engine.

## Low level libraries

OpenGL

DirectX

directly interfaces the hardware.

## Hardware

## Graphics cards

Nvidia

ATI

## GPU programming

card and control its behaviour (an advanced topic for later years).

# Overview and aims

By the end of the lecture you will be able to:

- Describe different types of 3D graphics software and how they are used
- Describe the mathematical representation of 3D space by coordinate systems
- Explain how 3D shapes are represented using polygons
- Model simple 3D shapes in blender

# 3D coordinates

in 2D space.

If you are dealing with pixels then x and y are integers, but if you make them

floats then you can access positions in any level of detail you want, by

being able to position things by fractions of a pixel.

In fact you can forget about pixels entirely and think of x and y as measuring for

metres (or whatever measure) in a virtual space.

## x, y, z

## x: left/right

## y: up/down

## z: in/out

# Overview and aims

By the end of the lecture you will be able to:

- Describe different types of 3D graphics software and how they are used
- Describe the mathematical representation of 3D space by coordinate systems
- Explain how 3D shapes are represented using polygons
- Model simple 3D shapes in blender

## 3D Objects

## Shape

## Surface properties

# 3D Shape

3D shapes are made out of polygons.

Flat shapes with straight edges.

You can put together several shapes to form a 3D surface.

We normally stick to simple polygons

Triangles

Quadrilaterals (quads)

Build more complex shapes out of these

more complex polygons are difficult for graphics hardware

## Polygons

## Vertex/Verteces

We define polygons in terms of their corner positions, called vertices

Each vertex is a vector (x, y, z)

## Mesh

A 3D shape made out of polygons is called a mesh.

## Geometry

Geometry is a generic term for objects made out of polygons.

You can edit shaped by directly moving individual vertices or groups of verteces (see the blender tutorials.

There are lots of methods for building shapes with polygon meshes. For example the extrude function allows you to create new polygons by stretching

out the mesh in a particular direction, again look up extrude in the

blender tutorials.

## Smooth Objects

Objects modelled with polygons can be quite blocky.

We often want smooth objects.

## Lots of Polygons

We need a lot of polygons to make an object smooth.

## Subdivison Surfaces

it is supported by Blender and other modelling packages.

You model a blocky shape with a small number of polygons.

The subsurf modifier then smooths it out by subdividing your

polygons into other, smaller ones.

# Overview and aims

By the end of the lecture you will be able to:

- Describe different types of 3D graphics software and how they are used
- Describe the mathematical representation of 3D space by coordinate systems
- Explain how 3D shapes are represented using polygons
- Model simple 3D shapes in blender