Fix #Unity3d’s broken OnMouseDown

This one has annoyed me for years: Unity’s OnMouseDown has never really worked. (NB: it works perfectly if you make a scene with a single cube; but that is not a game. It breaks completely as soon as you add multiple objects, colliders, etc to a scene)

The main reason to use a 3rd party engine is to avoid re-inventing the wheel; it’s tragic that Unity can’t even do mouse-input out of the box. Let’s fix it!

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Blender tips: set your 3D lights for edit mode

When you first install Blender, DO THIS!

Menu: File > User Preferences… > System

Screen Shot 2015-03-04 at 10.02.37

When you look at objects in edit mode, they’ll look something like this:

Screen Shot 2015-03-04 at 10.02.49

Why?

Blender makes it very easy to get a face back-to-front.

Or to have two faces overlapping.

Or … any number of other topology bugs. At best, these kill performance in any game that uses them. At worst, they cause nightmares for your programmers and level architects when Weird Stuff Keeps Happening. They can even cause crashes (e.g. a surface that has strange holes, or inside-out faces … and then gets processed by collision detection).

This lighting setup tells you at a glance if your normals are correct. Which in turn tells you if you have pieces out of place, or if you have an angle between faces that’s smaller/bigger than you expected (quite common to spot a pair of faces that have a sharper angle than expected/intended).

Bonus: 3D printing

If you’re 3d printing, the mistakes that slow down or crash a Game engine … will cause 100% failure of prints (Wasted time, wasted plastic – and in some cases I’ve seen: damaged printers!).

So, yeah. Getting this wrong can cost thousands of dollars. Don’t do it; replace Blender’s defaults with something sane that works :).

Blender UX for the lose

This should be the default. But then … Blender’s team seems philosophically opposed to doing anything the easy way :).

Unity3D: display a variable instantly on screen

You need this ALL THE TIME when developing, and Unity lacks it as a core feature:

  1. Create a Text label on your GUI
  2. Drag/drop a variable onto the label, and it will automatically display the value

Completely impossible, due to short-sighted design decisions in the Unity Editor from 10 years ago that never got changed. So, let’s fix it. It’s hugely annoying not being able to do this!

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Promoting an Indie game: what should you link to?

Background

Every Saturday, thousands of indie / hobbyist game developers publish screenshots of their in-progress games. Unlike most forms of marketing, this is:

  • honest / genuinely representative (it’s actual content)
  • interesting (show’s the dev’s intentions)
  • exciting (pictures of games are usually more fun than words)

i.e. … it’s an amazing marketing tool.

But many game developers are screwing this up. A year ago, I posted a long list of advice, tips, and explanations – worth reading. But some devs are still misunderstanding / screwing this up. So, what should you do?

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#Unity3D plugin review: Advanced Inspector

The author of Advanced Inspector gave me a free copy over Christmas. I’d considered it many times, and always ended up choosing not to buy, and write my own fixes/workarounds instead. So I was keen to try this out on a hobby project and see how well it works in practice.

What is it?

A replacement for Unity’s built-in Inspector. This (optionally) changes the editing interface for every single Component in your Unity projects.

Why do we need it?

When you run Unity, you get the standard multi-pane IDE that is the Unity Editor. Whether you’re a programmer, a designer, or an artist, this is your main portal into Unity, and the starting point for all your work.

Anything you select in the 3D/2D scene causes an Inspector panel to appear, with all the editable data about that thing. Unity’s built-in Inspector is very basic; by modern standards of GUI/UX, it sucks. Fixing GUI is very expensive, so instead … Unity has gradually been making the Inspectors more and more customisable.

Traditionally this was very hard to do; in the last 12 months it has become much easier, and Unity has unlocked more features. To date, I’ve not been sure if the 3rd party plugins are fully using the new features.
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Easy parametric animations in #Unity3d with code and curves

iOS forces you to use pretty animations: if you don’t tell it otherwise, it will use “ease-in/ease-out” curves to make things feel … smoother, less jerky.

Unity is made for programmers; changes you make to position, size, rotation, etc all happen instantaneously. By default, they won’t even animate, will teleport instead.

So … moving from “prototype with no animation” to “prototype that won’t hurt people’s eyes, and I can share”, what are some tips and gotchas?

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A Whiteboard Xmas Card for everyone

What can you draw with a whiteboard, if you’re not an artist? Let’s see..

Many of my friends live on different continents. It was too late to post cards, and I was staring blindly at my whiteboard when I had an idea: A picture for everyone, photographed, emailed … Then wiped clean. A transitory, ephemeral, virtual gift made out of something physical and real.

(there’s a background to this, see below the images)

PS: apologies for variable quality – I was doing these as fast as possible, trying to get them out same day (Xmas Day).

IMG_20141225_224459 IMG_20141225_225137 IMG_20141225_230807 IMG_20141225_231300
IMG_20141225_232047 IMG_20141225_233613 IMG_20141225_234827 IMG_20141225_235750
IMG_20141226_000710 IMG_20141226_012840 IMG_20141226_013834 IMG_20141226_014528
IMG_20141226_020551 IMG_20141226_021514 IMG_20141226_022811 IMG_20141226_030250
IMG_20141226_031039 IMG_20141226_032140 IMG_20141226_033113 IMG_20141226_122938
IMG_20141226_123945 IMG_20141226_125359 IMG_20141226_133850 IMG_20141226_134557
IMG_20141226_135051 IMG_20141226_155430 IMG_20141226_160437 IMG_20141226_220730
IMG_20141226_222932 IMG_20141227_172428 IMG_20141227_174607 IMG_20141228_171110

If you didn’t get one, well … Maybe you should keep in touch more, my friend!

But seriously: I’m not finished yet. Watch your inbox.

Background

This Christmas, I did my first serious drawing/painting in 15 years, as a gift for someone. I was surprised (actually: stunned) how well it came out. Unfortunately, it wasn’t appreciated.

I wanted to make something positive out of it, anything. I’d poured too much time into that, and too much care, to write it off and move on.

Here’s the results. I took the theme of my original hand-made card: an image specific to the recipient, something that they (and their close friends) would recognize and understand immediately.

There’s a few that tie obviously to well-known people in Web, Education, Games industries.

Unity’s failure as an Entity System, example 1: Selecting things

Entity Systems in Unity… some examples of the problems

This is a new series of blog posts, where I’m going to document specific ways + concrete examples in which Unity fails (sometimes spectacularly) as an “ECS” game engine.

I like Unity; but the core architecture (which is very old) is a half-assed ECS, and if we’re to upgrade it into a really good, modern, architecture … we first need to understand exactly where it’s failing, and why.

So, let’s start with Selecting Things…

Background

Game

A 2-player card game where each player normally draws a card each turn, and then plays one or more cards. Sometimes (e.g. when discarding because “too many cards in hand”) they have to select more than one card at once.

Initial version of game will be 1-player versus computer. Very soon: want to upgrade to OPTIONAL 2-players on-screen, with one using the mouse, other using gamepad. Ultimately, want to also add over-the-internet multiplayer (which ends up interfacing with the codebase in a very similar way to the original 1-player-vs-computer, so we can ignore for now).

Code Situation

Player taps card. Now … we must inform many other scripts and independent systems, so they can choose to eg.

  • ignore (if invalid for current state of game)
  • react (e.g. zoom to display the card more clearly)
  • “select” internally (side-effects include: deselect other things)
  • advance the game (if it was waiting-for-input)
  • ..etc

Problem

What/where do you send the “player clicked on a card; can some piece(s) of code PLEASE deal with this??!!?” ?

Addendum

In Unity, only the low-level “card” object can sensibly detect it has been clicked on.

Both Unity’s Physics (old) and EventSystem (new) effectively force this via their core design. Both require you to attach scripts to the physical objects that will be clicked.

In practice, this is bad for OOP (and bad for ECS too). When there’s e.g. 100 cards all of which must be separately clickable, your code is really in the wrong place. You don’t want cards (which sometimes are in a deck, sometimes on the table, sometimes “virtual” (perhaps in a virtual, unopened booster pack etc)) … to be containing all the GAME logic required to know what to do when they’re touched!

Classic Entity System / ECS solution

  1. Create a SelectedByPlayer component
  2. Add it to the card
  3. Sit back, and relax. Code that cares about input will scan “get me all SelectedByPlayer components” on each frame, and react accordingly

Everything works automatically; any System/Processor that’s “waiting for a selection”, or “making render changes when selections add/remove”, etc … will pick up what it needs, with no work.

You can add new input-handling routines simply by adding them. That’s all. No other changes needed.

Attempting to solve this in Unity

UNITY 4.6/5.0

Maybe … NB: I’ve only just started using the new GUI/EventSystem in Unity 4.6+ .. create a custom Input event, and a custom InputModule that can understand that, and then put all the code for ALL affected systems/processors into one monolithic ugly, hard-to-maintain script from Hell.

I suspect that this code will be quite maintainable w.r.t. adding new Input hardware in future – e.g. allowing mouse vs gamepad. But it’s going to suck at the rest, all the business-logic and handling. Which is going to be > 95% of the maintenance cost.

You get one small benefit: you can separate-out different inputs (click versus drag). Sadly, in reality: 95% of game actions will be simple clicks. This is one of those “the code architecture sounded great in academic situation, but reality is so unbalanced, it works out less well in practice” situations.

This is a classic OOP solution, and has the downsides. The only significant benefit I can think of is that it’s a “known” Hell: if you’ve done a lot of OOP game coding, you’ll be familiar with the pain you’re going to run into.

UNITY CLASSIC

Make a new class “CardClickManager” whose sole purpose is to reference all the possible bits of OOP code that “might” need to react, and which has to be updated by hand EVERY TIME you modify, add, or remove some input-handling code ANYWHERE else in the codebase.

Pretty much the same as above, except it:

  • … is even more simplistic (no event-dispatch systems)
  • … making it even harder to maintain + debug
  • … is slightly more proprietary

Conclusions / Improving Unity

So far, I cannot think of any sane, maintainable solution here other than “suck it down and use OOP, and suffer forever”, or “throw away Unity GameObject/Component, and implement a proper ECS”.

That’s fine, though. That’s the point of these posts – to hilight situations where there’s no good middle-ground, where we must create the data-centric, cleanly-separated architecture of a modern ECS.

Counter-ideas very welcome! Comment away, guys…

How much should you use a Scripting language when writing a Game?

Ask 10 game developers if you should use more script code or less, and you will get 11 different answers. They are all correct: it’s very situation-specific. Use of scripting languages is highly dependent on the humans and the practical / project-management issues.

Why?
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Makerbot Replicator2 Upgrade: new fan duct

I reviewed a whole bunch of these on Thingiverse, and the best combination of simplicity and effectiveness appeared to be this one:

…but you want to print these at 0.1mm layer height, or less, and that’s difficult with the model above. So I tweaked it a bit:

NOTE: The WordPress authors can’t be bothered to implement safe/secure uploads; instead, they block ALL uploads (which is very stupid and doesn’t solve ANY security problems). This file has to be renamed when you download it. Stupid, stupid, stupid programmers.

WordPress Is CRAP.stl

Changes

The original model has two small circular screw-holes. Makerbot printers can’t print these very well – Both the official slicer, and the main commercial / open-source slicers get it wrong and print the holes in a bad way (untethered; it’s an obvious heuristic to fix, but no-one has implemented this yet). Net effect: the holes slide about during layer 2, and usually detach, and ruin the print.

To fix this, I cut a slice out of each hole, making them into hooks. This follows the design of Makerbot’s original fan duct, and makes the print easy to do even at high speed and low layer-height.

3DPrinting tips: cooling, fans, and PLA temperatures

This is hugely important to 3D printing, and generally: no-one talks about it online (at least, not with any authority: more “blind leading the blind”). Which is silly: the engineering behind this is obvious (and it’s often obvious from looking at a 3D printer that it’s been under-engineered in this critical area).

NB: I don’t know which parts of “correct, obvious” cooling are blocked by stupid patents that should never have been granted. That might excuse the poor design of most printers today. Might.

My experience so far is that “more cooling of printed object is better”. But that’s an over-simplification…
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Towards a Unity3D ECS: what GUI? What features?

This year, one of my goals was to build a sane, powerful, viable Entity System / Entity-Component System within Unity3D. Something I could build current and future games on, and save a lot of dev-time (both in ease-of-use and in easily adding missing features that I wish Unity had).

So, progress?
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Site disappeared? Apache ARGH!

Transferring server to new home.

Allowed it to install latest versions of core software.

Turns out … the lovely people at Apache have made major site-breaking changes to their config system, so that upgrading WILL break existing sites.

Took an hour to discover that :(.

Epic saga of Unity3D deserialization of arbitrary Objects/Classes

(a summary writeup of the things I tried – based on this Unity blog post: blogs.unity3d.com/2014/06/24/serialization-in-unity/ – to get Unity 4.5 to correctly serialize/deserialize simple object graphs)

UPDATE: I belatedly discovered that EditorUtility.setDirty() is fundamental to Unity; if you have even one single call of this missing, Unity will corrupt data when you save the project. In some of the cases below, where everything was fine EXCEPT on fresh startup, I suspect that was the real problem: a missing setDirty(). I thought this method was cosmetic, but tragically: no.

This is not easy to read, it’s bullet points summarising approximately 2 weeks of testing and deciphering (plus a month or so spent learning-the-hard-way the things that are in the Unity blog post above. Note that the blog post only came out very recently! Until then, you had to discover this stuff by trial and error)

Serializable-thing:

– example on blog won’t work if e.g. your Class is an object graph.
– e.g. class Room { List doors; }. class Door { Door otherDoor; }
– …can’t be serialized. Can’t be stored as a struct, unless you have a GUID per “Door” instance. That’s no surprise, didn’t bother me: This is standard in most serialization systems.
– So we go on a quest to create a GUID…

GUID1:

– class Door : ISerializeCallback { Door otherDoor; public string guid = Guid.NewGuid().ToString(); /* use OnBefore / OnAfter callbacks to store the guid of the other door / find the door from guid */ }

Unity inspector lists:

– if you add an item to the list, 2 things corrupt your data:
1. all existing objects are NOT MOVED, but are CLONED into new list. This breaks our GUID.
2. the new item is a carbon-copy clone of the old – so it ends up with the SAME GUID (ouch)

GUID2:

– class Door { [SerializeField]private string _guid = Guid.NewGuid().ToString(); }
– now the inspector no longer clones the guid … BUT … instead it sets it to null.
– it seems to run the constructor, then use serialization to delete all values it finds

GUID3:

– class Door { private string _guid = Guid.NewGuid().ToString(); public string serializedGuid; /** use serialize callbacks to maintain serializedGuid */ }
– Disable the Editor’s list-renderer: it has at least two major bugs that corrupt data. Use the UnityEditorInternal.ReorderableList.
– NB: ReorderableList – with no customization – does not have either of the two bugs I saw with built-in Inspector’s lists.
– NB: as a bonus, with RL, we can avoid the “run constructor, delete all data, deserialize, reserialize” cycle, and directly create a new, blank instance with a safely generated – FRESH! – Guid.

Ctrl-D in Editor:

– breaks this, because we have no idea if a deserialize event comes from “ctrl-d” or from “read back from disk” (or from a prefab instantiating into the scene).

GUID4:

– class Door { public Room serializedRoom; private string _guid; /** use callbacks to peek into the serialized room, and use the guid as a “local ID within this room” */ }
– Because we’re now leaning on Room (which is a GameObject) to provide part of our GUID, in theory we don’t care about prefab/ctrl-d/etc — the code inside MonoBehaviour will automatically separate-out those cases for us.

Work with everything except prefabs, I think

– eventually gave up, removed the GUID completely, and changed game design to only allow ONE door to connect any pair of rooms. Yes, I was desperate!

THIS WORKS! Until you restart Unity:

– restarting unity causes this to deserialize on a different thread, and now you’re NOT ALLOWED to peek into the serialized room. You cannot use it as a substitute ID. You get crashes at load-time).
– …apart from that, this works fine. We have a solution that worked for ctrl-D, for prefabs.

GUID5:

– class Door { public Room serializedRoom; private bool _isUnityStillOnBackgroundThread; /** use the bool to say “deserialize happened but the data is NOT VALID, DONT RUN ANY METHODS” */ }
– …also use an AutoRun script with [InitializeOnLoad] and “EditorApplication.update += RunOnce;”
– …the autorun script waits for Unity to startup, then goes and Finds all objects, and finds all Rooms, all Doors — and does the fixup.

Fail, but can’t be debugged:

– I have no idea why this failed. It appeared perfect. Simply moving code that worked inside the deserialize (but crashed because it was run on “wrong” thread) out into the post-launc RunOnce method … silently fails. No errors, but no data.
– NB: this is impossible to debug, because we can’t even call ToString() on the deserialize method :(.

Conclusion

Give up. Make 10,000’s of Component instances instead. Waste memory, kill performance (especially at runtime: imagine how bad the AI’s going to be iterating over this!) but hey – IT WILL WORK. Because it leans on the built-in hacks that MonoBehaviour has had for years (which we’ve all been using millions of times a day without realising / appreciating ;)).

Debugging A* Pathfinding in Unity

I needed fast, efficient, … but powerful, adaptable … pathfinding for my hobby project. My minions have to fly, walk, crawl, teleport, tunnel their way across a procedural landscape. Getting to that point has been tricky, but the journey’s been interesting.

We want something that intelligently routes creatures around obstacles, and picks “shallow” routes instead of scaling cliffs (or vice versa for Giant Spiders etc). Something like this:

Screen Shot 2014-08-10 at 20.09.36

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OpenGL ES 2 – Video on iPhone in 3D, and Texture-Map sources

This is a blog post I wrote 6 months ago, and my life got too busy to finish it off, finish testing the code, improving the text. So I’m publishing this now, warts and all. There are probably bugs. There are bits that I could explain better – but I don’t have time. Note that the code is ripped from apps where I ACTUALLY USED IT – so I know it does work, and works well!

In brief:

  1. Using different “sources” of textures in OpenGL, not just images!
  2. Using CALayer’s as a source — allows for video in 3D!
  3. Using “Video straight from the video decoding chip” as a source – faster video!

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