Cross-platform physics games

Using MonoGame and Farseer Physics

Rune Andreas Grimstad @runegriCapgemini Norge

What to expect

• Lots of code!

• Intoduction to MonoGame and Farseer

• Playable demos

• Code on GitHub for you to play with :-)

What NOT to expect

• Deep dive into the features• That would take days...

• 3D games• Visit Richard Garside’s talk tomorrow at 11:40

• A complete game

Who am I?

• Rune Andreas Grimstad

• Lives in Trondheim

• Works for Cagemini

• Focus on .Net and anything mobile

• Programming since I was 8 years old...

Why games programming?

• Not my job!

• Fun

• Learning

• Becoming a billionaire after creating the next Angry Birds Flappy Bird!

MonoGame

• Open Source implementation of XNA 4

• Runs everywhere

• C# / .Net

• Xamarin

Fez

Bastion

Draw a Stickman Epic

Transistor

MonoGame – getting it

• Download from monogame.net

• Clone from GitHub

• NuGet

MonoGame – features

• Supports all features of XNA4 (more or less)• 2D• 3D• Content pipeline• Input• Sound and music• Networking

• It’s a bare-bones framework…

Enough background!

How MonoGame works - The Game Loop

Initialize and load content

Update game state

Draw everything

Unload content

How MonoGame works - Creating content• Most file types are supported

• Either use an XNA content project• Requires XNA Game Studio, so Windows only• Create a MonoGame Content project

• Or use the MonoGame Content Builder• Runs everywhere• Not 100% done yet, but getting close

How MonoGame works - Loading content• Using the ContentManager.Load method• Usually Content.Load<Texture2D>("spaceship");

• You can also load other resources this way• SpriteFont, SoundEffect, Song, and so on

• Store the files in the Content folder in your project• Build Action – Content • Copy to Output Directory – Copy if newer

How MonoGame works - Drawing stuff• Use the SpriteBatch class

• Start with SpriteBatch.Begin• Do your SpriteBatch.Draw calls• End with SpriteBatch.End

• Try to limit how many SpriteBatches you use

Demo 1

• The basics

• Draw a sprite on screen• Content• Animation• Camera, pan & zoom• Input

Demo 1 – What did we learn?• Game loop• Content• SpriteBatch• Texture atlas• Camera• Input

All that from this little guy!

But there is more

Farseer physics

Farseer Physics Engine is a collision detection system

with realistic physics responses.

Farseer physics

• 2D Physics simulation• Collision detection• Objects with any shape• Friction and restitution• Joints• Gravity... and more

Farseer physics – getting it

• NuGet

• Download from https://farseerphysics.codeplex.com/

• Build from sources• The easiest way to combine with MonoGame?

One thing to be aware of

• Farseer uses the KMS system (Kilo, Meters, Seconds)

• Use the ConvertUnits class

• Init with SetDisplayUnitToSimUnitRatio

• Use ToDisplayUnits and ToSimUnits

Your screen

Display coordinates: 1920 x 1080 pixelsFarseer coordinates: 19.2 x 10.8 meters

Demo 2 – more Bubble Bobble!• A simple platformer

• Simulates a world• Sprites are bodies in the world• Collision detection• Movement

Bubbles!

Demo 2 – what did we learn?• Using Farseer!• Worlds• Bodies• World and display coordinates

More features of Farseer Physics• Polygon shapes• Turning an image into a polygon in the game world

• Complex objects• Combining many shapes into a single object

• Joints• Attaching bodies to each other

Demo 3 – Exploring the cave• Stupid game with lots of physics

• Polygon objects• Complex objects• Disabling gravity• Attaching objects

Polygon shapes

Turn this... ... into this

MAGIC!

Polygon shapes

Complex objects

• Add many shapes to one body

Complex objects

• Join bodies using joints

• Revolute joints can be used to create a chain or rope• Use the RopeJoint to set the length of the rope

• The possibilities are endless!

Finally

• There is much more to MonoGame!

• 3D – Richard Garside will talk about this tomorrow!• Pixel shaders and effects• Sound and music

• Use the SoundEffect and Song classes

• Input beyond the keyboard• Mouse • Touch • Joystick

Finally finally

• Find my code samples on GitHub• github.com/runegri

• And my slides on SlideShare• slideshare.net/runegri

Get in touch

• I’m here for the rest of the conference

• Twitter: @runegri• Email: rag@rag.no