Salomonsson.se
Sep 14 2017

Metro Siberia - part 2

Matrices!

Small progress. Started porting over my matrix implementations from haxe. At the moment it actually looks more like C-code than C++.

Been playing a lot with arrays and pointers. Even some memcpy!

Aug 24 2017

Metro Siberia - part 1

intersecting triangles

Started a re-make of my old game Metro Siberia in C++. This is the big plan:

  • Custom rendering methods in it’s own header file
  • Game code is platform independent
  • To start with, only draw lines and simple fills
  • Currently using OpenFrameworks as “backend”, because it is almost zero hassle to get working
  • Plan is to change from OpenFrameworks later on… but we’ll see. At least the structure will allow it.

Currently nothing more than a window that renders the picture above.

Apr 24 2017

Behavior Trees in Unity

How do you create a nice user (developer) friendly Behavior Tree in Unity? The hardest part with BT’s is not making them, it is maintaining them! As they scale they become pretty hard to grasp, and you need good visual tools to debug. But I just got an idea that I want to write down somewhere before I go to sleep and forget all about it.

First some links

Introduction to BT’s, if you don’t know them:
http://guineashots.com/2014/07/25/an-introduction-to-behavior-trees-part-1/

Interesting project with viusal editor (though way to buggy to be used, and also I don’t like the performance warning in the readme):
https://github.com/rev087/hivemind

Here is a rundown on how to create a similar visual editor, using Scriptable Objects:
http://davidlegare.ghost.io/behavior-trees-1/

And lastly, you might have to read up on ScriptableObject as well:
https://unity3d.com/learn/tutorials/modules/beginner/live-training-archive/scriptable-objects

The idea

So, ScriptableObject has some problems for our usecase: It does not support polymorphism. So here is the idea on how to solve it.

  1. A BehaviorTree class, with custom PropertyDrawer
  2. All the basic nodes are built-in into BehaviorTree, such as Sequence, Parallel, Repeater and so on
  3. Custom Condition and Action nodes are added as MonoBehaviours to the gameObject (and thereby serialized with all their properties), but added by reference as a nodes in the BehaviorTree

It’s not a pretty solution, but to me it beats most of the other solutions I have seen. Then it’s just a matter of building that custom inspector for the BT.

Mar 30 2017

Ripple Haxe Port, 1

Finally started on something I’ve been wanting to do for a very long time. A serious try to port Ripple Dot Zero to haxe, so I can compile it to c++, run it on Windows with full gamepad support and full, smooth framerate!

This is after a few hours of experimenting with openFLs new Tilemap API, and one day of porting (well… mostly rewriting) the tile rendering part of my old engine. Now it runs on a solid 60 fps after compiling to C++, even though there are tons of optimizations to be done.

Right now it renders all static tiles (no animated tiles, and no sprites) from an existing level, and lets the camera move in a huge sine wave over it.

A very promising first step!

Mar 29 2017

Simple Algebra

I always forget or mix up how to extract variables from a formula when division is involved, which always slows me down as I have to sit with pen and paper to get it straight. So lets just get it straight and simple here, so I can look it up whenever I need it!

(Note: the one furthest down is the interesting one. Not even sure why I have addition in there, but I let it stay.)

Mar 23 2017

Hamster Hoops

Three months after the initial release we added Pass and Play functionality to Wonderglade, and at the same time added a new mini-game.

I think it is worth mentioning this update in its own post as Hamster Hoops is (in my own humble oppinion) the very best of all the mini games. In this game the greatness of our team really shined through!

I spent over two weeks just prototyping the controls (turns out throwing basket balls using a 3-DOF Daydream controller is not only more difficult than you can imagine, it’s pretty much impossible), and also working very close with our new, and extremely talented game designer to make the challenge interesting enough. Not to forget the awesome 3d-artists who implemented most of the art during the two days I was home sick with the flu.

Jan 15 2017

Kingsmountain, Part 2

“Don’t worry about the dog, he’s very nice and only wants to play!”

Jan 02 2017

Wonderglade

Wonderglade is the second game from Resolution Games I worked on (also the second game they released). It’s a collection of mini games in a theme park setting, and it was released for Google Daydream, their mobile vr project. The game was released for free, and has really good ratings!

Screenshot from Google Play Store, taken 25 sept 2017

Dec 15 2016

Kingsmountain, Part 1

A while back I found all the raw material for a game me and Simon were working on a long time ago (actually before both Ripple and Metro Siberia, so somewhere around 2006 – whoa, thats TEN YEARS ago!!) called Kingsmountain, and I’ve been playing with the idea to try and recreate one of the minigames.

My first attempt was with Haxe, and a 2d skeletal animation tool called Spine. However, the Haxe runtime implementation for Spine was buggy as hell, and I spent many hours trying to animate the running little dude, but finally the bugs made me give up.

Instead I restarted the project in Unity, and here you can see the result after just about 2-3 hours.

Oct 31 2016

Creative Parental Leave!

Today is the last day of my parental leave. For 6 months I’ve been home with my twin daughters (they were almost 9 months old when I started, and soon 16 months).

I’ve spent a lot of time with them, but I have managed to stay creative in the few hours every now and then when they were taking naps. I have to say I’m a bit impressed in retrospect!

READ MORE >>
Oct 31 2016

Math - Triangle Rasterizer

Warning: lengthy post ahead! But lots of really cool stuff!

Been a while since I posted now. There are a couple of reasons for this:

  • First of all, I decided to write my own software triangle rasterizer (I’ll get to explain what that is in a bit)
  • It’s a lot of math involved. And a lot of diagrams with pen and paper. I has spent several hours to get it to its current working state
  • My parental leave is getting close to the end. My kids are now almost 16 months and require a lot of attention! Have not gotten any computer time at all for the past three weeks

But now I finally have something to show, so lets show it!

READ MORE >>
Oct 12 2016

Markdeep

A few days ago I came across Markdeep. A simple way to write formatted documents using markdown syntax.

I think markdown syntax is nice, and I’m already using it for all content on this site.

The idea is that you only need a small snippet of javascript text in the bottom of the document. You edit it in your regular notepad app, and view it through a browser. It will fall back to unformatted markdown text (still pretty readable) if it cannot fetch the javascript file.

However the original markdeep.js has a big flaw. At least for me!
It cannot detect single line breaks!
Like this one.
So I modified it a bit.

If you want to use it, just copy and paste the following snippet in the bottom of a text document, and make sure the file ending is .html.

<!-- Markdeep: --><style class="fallback">body{visibility:hidden;white-space:pre;font-family:monospace}</style><script src="http://salomonsson.se/md/markdeep.min.js"></script><script src="http://salomonsson.se/md/markdeep.min.js"></script><script>window.alreadyProcessedMarkdeep||(document.body.style.visibility="visible")</script>

You might want to paste the following at the very top
<meta charset="utf-8">

View a demo page with all the features

Oct 05 2016

Math - Backface Culling And Directional Lighting

Up to this point I’ve only drawn wireframes. To create colored 3d objects I need two things. Backface Culling and Z Sorting.
Time to start with the first: Backface Culling.

  • First of all I changed to using triangles instead of just points/lines.
  • Then I calculate the cross product on two of the sides to get a normal vector.
  • Compare the normal with your viewing vector (a line from the camera to the middle of the triangle) to see if the triangle is facing towards you or away from you
  • Don’t draw if the triangle is facing away from you

Now you no longer see any lines “behind” the cubes.
I also draw the normal vectors for each triangle.

Spinning cube with normals

From this point I just filled the triangles with a single color.

Red spinning cub

With the normal vectors already calculated on each triangle, I tried to implement some directional lighting as well.
It went much smoother than I would ever have thought.

Yay, lighting!

Pretty interesting! I made a spinning cube with lighting almost exactly ten years ago. However I did not understand much of it, and going back to that tutorial it seems to be full of weird tricks. This time however I did it all by myself =D.

Next up is Z-Sorting so we can have more than just one cube at once

Sep 22 2016

Math - The Camera Matrix

We can move around in our 3d world!

I’m doing serious progress! Today I managed to get the camera matrix working!

The coolest thing about this is that just a few months ago I would have thought that this was too much math for me to ever be able to understand! Remember that I have written everything from scratch - except for the line render code, which is basically just a lineTo(x,y) function. Even the matrix implementation.

There’s no frustum culling in there yet (except for any z-values behind the camera) so pretty much everything gets drawn all the time.

Resources for camera matrix:
Camera View Transform Matrix
Faster Matrix Inversions

Sep 15 2016

Math - 3D and Perspective

In our last blog post we used matrices to translate, rotate and scale vectors, but so far only in 2D.

Transforming vectors in 3D is pretty much the same thing. The only difference is that we cannot directly plot those vectors out on the screen since each vector will come in a triplet of {x,y,z} and the screen only consists of {x,y}.

We could just ignore the Z-coordinate, but that would look weird!

No Perspective

To get it to look right we need to apply perspective. Perspective means that an object that is further away from our eye will appear smaller than an object that is closer!

Perspective

Applying perspective to 3D-points is something I’ve been able to do for a long time, but now we’re working with matrices, and of course there is something called a perspective projection matrix!

Another great resource I found on the subject is scratchpixel.com, here on Perspective Matrix Projection.

In the past when I’ve been playing with 3D, I’ve used trigonometry for all transformations. It works, but has several drawbacks!

  • More computation heavy! Needs to do Sine and Cosine lookup for each point!
  • Much more complex to nest parent/child-relationship!!
  • Viewing from a camera… I don’t think so!
3D with trigonometry (and fancy blur), made 2006

Using matrices is superior by far. The image below is just a couple of matrices combined, using vectors forming a cube and a pyramid. This would not have been possible using my old 2006 methods!

3D with matrices

If you want to read up on this too, then check out:

Math for game developers youtube channel
And http://www.scratchapixel.com/index.php?nocategory