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SE 350 – Programming Games

Lecture 7: Programming with UnityLecturer: Gazihan Alankuş

Please look at the last slide for assignments (marked with TODO)

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Outline

• Exam talk• Rest of the semester• Continuing with Unity programming

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Midterm

• How was it?• Suggestions? Concerns?

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Rest of the Semester

• Some homeworks, maybe quizzes?• Major focus is on developing and finishing

your games– Some weeks will be development workshops• Probably starting next week. Bring laptops!• Bring designer friends if you like.

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Recap what we learned

• Game objects, components• Prefabs, assets• Classes and structs, – sharing references vs. copying

• Accessing other objects– gameObject, GetComponent<Component>(), – Standard components (transform, renderer, etc.)– GameObject.Find(“name”)– transform.parent

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Recap what we learned

• Functions that you write and that Unity calls– Awake, Start, Update, OnCollisionEnter, …

• Making connections (getting references to other objects) in Awake()

• Visually decide what to do on the interface, use it to write code

• Instantiate()/Destroy() objects during runtime

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Things that we will learn about

• Basic data types– Vector3 (position, direction, displacement)– Quaternion (orientation, rotation)

• Details of standard components– Transform, Collider, Renderer, RigidBody

• Basic data structures in C#– List, Dictionary, etc.

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Vector3

• Vector3 means “three dimensional vector”• Just three floats: x, y and z• Often used for talking about a 3D position or

direction– Contains methods/properties that help in this

domain• e.g., transform.position is a Vector3

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Vector3: related to magnitude

• v.normalized• v.magnitude• v.Normalize

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Vector3: some constants

• Vector3.zero == new Vector3(0, 0, 0)• Vector3.one == new Vector3(1, 1, 1) (LOL)• Vector3.forward == new Vector3(0, 0, 1)• Vector3.back == new Vector3(0, 0, -1)• Vector3.up == new Vector3(0, 1, 0)• Vector3.down == new Vector3(0, -1, 0)• Vector3.right == new Vector3(1, 0, 0)• Vector3.left == new Vector3(-1, 0, 0) 2/10/2012

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Vector3: Averaging (interpolating)

• Vector3.Lerp(v1, v2, fraction)

• Vector3.Slerp(v1, v2, fraction)

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v1 v2

0 fraction 1

v1 v2

0fraction

1

origin (0, 0, 0)

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Vector3: Geometric operations

• Vector3.Scale(v, s)• Vector3.Project(v, vbase)• Vector3.Angle(v1, v2)• Vector3.Distance(v1, v2)• Vector3.Dot(v1, v2)• Vector3.Cross(v1, v2)

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Vector3: operators

• v1 + v2 – Adds x, y, z values separately and returns the sum

vector• 3.5 * v– Multiplies x, y, z with 3.5

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Quaternion

• Has four values (x, y, z, w). What are they?– Don’t worry about its mathematical definition (has four

values, etc. don’t care because they won’t make sense in our context)

• Is simply (both of these below are true)– A vector and an angle

• Rotate around that vector with that angle– Three consecutive rotations around z, x and y axes

• Represents– Orientation (rotate to here from default orientation)– Rotation (change in orientation)

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Quaternion

• q.x, q.y, q.z, q.w– DON”T CARE!!!1!!!– NEVER USE THEM!!!!! >:@

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Quaternion: its value that makes sense

• q.eulerAngles– Vector3 that contains rotations around axes– Rotation order is z, x, y (but you don’t have to

care)• q.ToAngleAxis(out angle, out axis)– sets the angle and axis variables that you give to it– rotation around that axis with that angle amount

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Quaternion: operations• q1 * q2

– the result is the rotation that is equal to: rotate with q2 first, and then with q1

– or, if q2 is orientation of something, rotates it with q1 (same thing, slightly different interpretation)

• q * v– rotate v with q

• Quaternion.Dot(q1, q2)• Quaternion.AngleAxis(angle, axis)• Quaternion.Euler(x, y, z)• Quaternion.Inverse(q)• ...

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Quaternions: Averaging (interpolating)

• Quaternion.Slerp(q1, q2, fraction)– The correct way to interpolate two quaternions

• Quaternion.Lerp(q1, q2, fraction)– Slightly faster, bad interpolation (moves faster in

the middle)

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There are more

• Ray, Rect, Vector2, Vector4, etc.• Use the scripting reference– Help > Scripting Reference (in Unity window main

menu)

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Standard components

• Have – Properties (variables)

• Can’t modify• Can set for instance

– Functions• Can call for instance

– Class functions (static)• Can call with class name, without an instance

– Messages• Functions are called on all components that are attached to

the GameObject when events happen

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Transform• transform.position• transform.rotation

– With respect to the world. Changes when parent changes.– Not what you see in the inspector.

• transform.localPosition• transform.localRotation• transform.localScale

– With respect to the parent. Does not change when parent changes.– What you see in the inspector

• transform.right, transform.up, transform.forward – x, y, z axes of the orientation (the arrows you see)

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Global vs. Local

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p

c

p.position ==

p.loca

lPositi

on

c.localPosition

c.position

c.transform.parent == p.transform

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Global vs. Local

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p

c

p.position == p.lo

calPosition

c.localPosition

c.position

Red ones changed as a result of moving the parent

All of this is the same for rotation and localRotation

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Renderer

• r.material• r.isVisible

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Colliders

• c.isTrigger– True• Not used in physics calculations, lets things through• OnTriggerEnter is sent to the GameObject (and its

components)– False• Used in physics calculations, won’t let things through• OnCollisionEnter is sent to the GameObject (and its

components)

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Colliders

• c.material– The physics material (PhysicMaterial)• friction constants• bounciness

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Standard components• Have

– Properties (variables)• Can’t modify• Can set for instance

– Functions• Can call for instance

– Class functions/class variables (static)• Can use with class name, without

an instance. Like global variables but in class.

– Messages• Functions are called on all

components that are attached to the GameObject when events happen

• Examples– t.position = t.position + Vector3.up;

– t.Translate(1, 1, 1)

– Vector3.Lerp(v1, v2, f)– Vector3.up

– Update()– OnCollisionEnter() – OnCollisionEnter(Collision collision)

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There are many other components

• Use the scripting reference!

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Keeping Game State: Data Structures

• You will have to handle information about your game

• Examples– List of enemies– Accessing enemies by their names– Enemies sorted by their distance to the character– The friendly NPC that the enemy is chasing

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Data Structures

• Hold references to other objects– GameObject enemy = GameObject.Find(“enemy”);• Remember pointer fun with binky. This is just a pointer.

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Data Structures in C#• using System.Collections;

using System.Collections.Generic;

• List<GameObject> enemies = new List<GameObject>();– loop with foreach, access enemies[5]

• Dictionary<string, GameObject> enemiesByName = new Dictionary<string, GameObject>();– access by enemy name. enemiesByName[“wolf”]– loop with foreach

• Amazing resource: http://www.dotnetperls.com/• Also should watch:

http://channel9.msdn.com/Series/C-Sharp-Fundamentals-Development-for-Absolute-Beginners/Working-with-Collections-21

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Game Structure• You will have GameObjects for various elements in your game (character,

enemy, robot, etc). Create their own scripts and put code specific for them.• You also need to have code that is common for the game (scoring is an

example). Attach such scripts on the camera or on a similarly unique object.• Wire them up in Awake()• For common singletons, create

– static MyScript instance;– public static MyScript getInstance() { return instance; }– public MyScript() { instance = this; }

• And in other scripts, – MyScript myScript = MyScript.getInstance();– Easier than GameObject.Find()

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TODO: Projects

• If you are not sending reports, I think that you are not working on the projects.

• Every member of the group will send me a separate weekly report about what you did that week about the project– This is private. Do not share with others. – Just write it as an e-mail. No attaching word

documents or pdfs please!– Send them every Thursday night!

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