Archive for the ‘Bold Pixel Engine’ tag

BADJ Day 3 (and 4!): Physics continued

Howdie!

Nape wrapper is almost wrapped… pun intended, but first, apologies for the missed day 3. While Marco was working on the Hajime trailer I was surfing the waves of wrapping a physics engine. Before moving forward, a big thank you to deltaluca for helping out!

Although not necessarily final, the current wrapper consists of:

Core

This class basically controls the behavior of Nape’s space. Due to its nature, Nape wants simple things to be done quite often, for instance, if you want to change gravity, you need to wake all objects. Core does these small things for you.

Entities

Physics entities basically wrap Nape’s bodies. The abstract entity (if you don’t recall how we are using abstract classes in Bold Pixel, check this out) will offer most if not all of the functionality. Although this means that the class is not really abstract, it also means that classes that inherit from this can and should be used as presets. Currently we have a simple box, simple circle, core walls and a explosion.

As time goes by more and more presets will be built, that’s the whole beauty of it!

Debug View

This class allows for fine lines to appear on screen so we can degub objects positions and so on. Quite useful for blit, not that useful for display objects since it uses Nape’s assignGraphic method. The debug view observes if there is a display object assigned before drawing the debug sprites. This means that if a object is already skinned, it won’t have a debug sprite.

A simple test

The SWF below uses the wrapper exclusively. The walls are a non-skinned PhysicsCoreWalls object. The light wood boxes are also non-skinned so we can see the debug sprite, but the bitmap is handled manualy. The objective of this is to show how blit objects will look if debug sprite is present. The dark wood boxes and the rock circles are a normal body with a assigned graphic, so, no debug sprite is created.

Plans for tomorrow: have a bang with Nape… almost literally! Until then, click the SWF underneath to watch a simple simulation.

Click the SWF above to see the test…

BADJ Day 2: The Nape Wrapper

Hello again.
Like the previous days, I can’t really say we are already on full speed with Bruce Ali, mostly because there has been some loose stuff on other projects we had to deal with. After lunch I was able to pick on something that was on my task list for sometime: the physics!

We will be using Nape for physics. Nape is a physics engine developed by Luca Deltodesco (aka deltaluca on FGL and Nape’s forums) that focuses on performance. For more about Nape, visit also the Project Page on Google Code and the Documentation.

We’ve been authorized by Luca to make Nape a part of Bold Pixel. In order to do this work, Bold Pixel releases (starting at v2) will include the AS3 SWC and our own wrapper. The wrapper is being designed to provide presets, easy management and a debug view that can be integrated with both other pieces of Bold Pixel (namely and most evident good use is the blit engine) or a typical Flash/AS3 project. Obviously it will have a lot of conventions and to make full use of Nape you’ll need to know how to use it, but the worst case scenario is that any coder will much less code to write and maintain.

We wish the best of luck to Luca and wish we can pull a lot from Nape and Bold Pixel. As soon as we have a tech demo of what we are doing with it, I’ll post it.

See you all tomorrow!

Vlad out!

Bold Pixel’s Namespaces and Interfaces

After much thought and discussion by myself or at the FGL chat I made some decisions about how to make Bold Pixel more modular in order to simplify my own work. Since we are still on top of contracts, I couldn’t give enough attention to this but my brain was dealing with it in the background.

Inheritance Spaghetti

The problem presented was somewhat simple. My early coding of the blit engine got tangled in the dreadful inheritance headaches. My solution to it was to create one class per major responsibility. It worked fine until the time I decided to expand one of the classes to do something it wasn’t designed to do. So on one hand I solved the inheritance problems but on the other I lost modularity. At this time I had a OOP doubt that I expressed in the FGL forums and the discussion that started there really helped me to move in a different direction, one that I had never considered.

More over I said that I would not support requests that didn’t deal with deal with real problems we had in our own development. And while I stick to that, I couldn’t help but to think: what if Bold Pixel could help someone but it missed one little tiny feature? While this was puzzling me, there was real problem, one with impact in our development that was taunting me…

The case of Blit vs Physics

So Bold Pixel has a blit engine and it will wrap a physics engine (more about the physics engine this later this month) so the question that was on top of the table was: considering there is a blit entity and a physics entity, which one should access the other? Whatever the answer was, modularity was lost in the sense I imagine it. I don’t want blit to know physics and I don’t want physics to know blit!

After a nice chat with Antriel at FGL (thanks mate!) I got to know the Strategy Pattern and all my problems were solved. In simple terms, I will be defining interfaces for all interchangeable objects but the implementations of the interfaces can exist anywhere. In the case presented, a blit entity will have its spatial properties (rotation, x, y and scale) defined by a spatial interface. By default it will be a simple class and it’s needed since the properties of the spatial interface are needed to render bitmapdata. A physics entity will be a implementation of  the spatial interface, so if I want to use physics on a blit entity, I simply write: myBlitEntity.position = myPhysicsEntity;

Visibility and Access Issues

This brought another problem. Bold Pixel has always kept its inner “stuff” hidden. The objective was this was to keep the auto-completion short and the use easy preventing mistakes. In order to implement interfaces I would have to make a lot of code public.

The answer to this would be abstract classes, but ActionScript3 does not support it. That will be addressed with simple naming and convention over configuration. Any class in any namespace in Bold Pixel that starts with Abstract will only have the simplest shortest implementation needed for something to work. For instance, if I want a blit entity that draws pixels I will have to extend a AbstractBlitEntity class (I guess that will be the name) but that brings another problem…

So ActionScript does not support abstract classes… convention will say that Abstract defines an abstract class.

Namespaces (to wrap this up!)

To have a better code organization I will need more packages and to have more packages I will need to provide access to classes in different packages. This will be done with namespaces. The only thing that annoys me is that Flash Develop in the current version (3.2.2) does not support code-completion with custom namespaces, but what matters is that using custom namespaces solves two problems. First I can have a bunch of private functionality like I like, but second, any coder can with a simple namespace use extend Bold Pixel to his own needs in a full modular way.

While I reckon that this is all just in my head and that a lot of work will have to be done and even considering that probably this will make Bold Pixel a little bit more complicated to the average coder, I feel it sorts a lot of questions, so: Namespaces and Interfaces FTW!

Bold Pixel Engine v1 Post Mortem

I guess it’s pretty strange to have a post mortem of something that is not a game, but Bold Pixel Engine, in its first version was a fantastic learning experience, but it had a overwhelming amount of failures also. To sort my thoughts I checked the tag of the engine in our blog and read some of the stuff that happened as time passed. This led me to write this post mortem, on one hand to know exactly what is right about it, on the other hand to learn from our own mistakes.

A bit of historical perspective

Bold Pixel Engine started with our first flash game because of a simple music management class. Back then, both me and Diogo were coding and I remember (and I admit I deeply miss) our discussions about code standards and organization. I’m a bit of a dictator when it comes to have stuff organized, credits to Marco that has used the word “dictator” more than once and with a large amount of reason and giggles.

Soon our bunch of classes were our own internal library and I even posted some of my own experience while organizing that library. Some of the most important definitions of Bold Pixel where then starting to emerge. July 27th 2009 we announced Bold Pixel Engine was alive.

I was quite excited about it!

The turning page from internal library to public engine was the blit engine. We had so much help from many amazing developers that we would not keep it for ourselves. We wanted to share, we wanted to hear what others had to say and that’s what we did. After two games under his belt and a lot of opinions, the engine was publicly available and his version 1 life was pretty much that until the version 2 turning point a couple of months ago… but I’ll get to that eventually.

What went right!

The learning process was amazing code wise. After Diogo left I really had to raise my standards and get to work and the engine allowed that. Coding such a piece of technology made me contradict myself several times and pushed me forward. I’m absolutely convinced that I am a much better ActionScript programmer now than I was before and I feel I learnt little from the games but a lot from the engine because I forced myself to respect the principles I wanted to see applied to it.

And speaking of principles, these stay true from the first line of code until today and are something that really went right. And these are:

Convention over configuration: Bold Pixel Engine is written assuming some conventions. For example, if the programmer tells the Scene Manager to create a new scene, the previous one and all dialogs will be removed, which makes a lot of sense but maybe it makes less sense to say that all scenes have their pivot point at 0,0. This means that scenes and dialogs are simply added to the display list and that’s it, nothing to configure since there is a convention.

Ease of Use: This goes hand in hand with convention over configuration. If there’s something that really makes my head hurt is to look at the code needed to make something happen in libraries like Flixel and Box2D. I appreciate the effort put in these libraries and the flexibility and power provided but I believe that if we have to configure every single tiny detail the code becomes cryptic and extremely difficult to debug. I don’t mind loosing flexibility because I will create more mechanisms that will help me achieve my goals as time goes by.

Modularity: There is only one dependency in Bold Pixel Engine, which is the Manager class. If you want a single loop or to manage scenes and dialogs, you need to start it up. Apart from that Bold Pixel Engine started modular and will stay modular. The reasoning behind this were two questions I made once:

1. What if I don’t want to use the blit engine?
2. What if I want to add something that will wreck dependencies?

The answer to that was that I wanted it to be flexible, meaning, I can use whatever I want with only one dependency and that’s it. I don’t want the engine to behave like an engine. I want it to be a toolkit at my disposal. I even had a laugh about this.

What went wrong…

First and worst aspect of thing that went wrong was that I did too much stuff that we didn’t need that was requested and I didn’t do it with the same dedication I did the rest. That will never happen again. I’m convinced I got carried away by the kindness of a lot of devs, but we can’t have the engine restricted to the needs of others, which was something I said it wouldn’t happen from start. But what it really makes me feel bad about it was that other devs got involved in the project and this collided with either our work or their work making it a bad solution for everyone.

The second thing that went wrong was that I overcomplicated somethings because I felt it made sense. For instance there is a Scene Manager and a Input Manager and a Manager. All of these managers depend of a Display Object and/or its stage. While it sounds easier to manage code and it looks more tidy and clean, having a gazilion classes doesn’t make it easier to code with. I found myself looking through the classes to find what I wanted… that doesn’t sound like a good thing, right? I mean, I coded it!

And last but not least, I think I really rushed things. The idea behind the public releases of the engine were that we would make two games between each release, which we actually did with v1, but as soon as I had the mechanics ready and all the engine’s juicy code was on a actual project, I went head over heels with it. It lacked documentation, it lacked cross-testing (so, just because I did two games, I should have tried against the two games again) and most important it lacked a critical look and a some honest and critical analysis.

Conclusions

Great experience and I really appreciate all the kind words that I got from developers. I think the really cool thing that most developers got from it was the ease of use, probably the YouTube channel with some nice overview on it. I could’ve written a post trying to sell the idea that we are overwhelmed with joy and l33tness, but I would be failing to be honest. I truly believe that BPE v1 is a great piece of software, but I was naive in the approach and maybe over-friendly in the “pleasing my fellow devs” department.

We have a game going with v2 and I think I sorted my doubts about what is going to happen with the engine. Many things that were wrong with v1 are already gone and there is a lot of stuff that isn’t even started, like moving the Music class which started all this into the current version.

There’s a lot to be said about v2, but this is a hell of a long post mortem and I’ll write about that soon.

Random thoughts on life and code

Been a while since I write here. This post will be a bit like therapy.

So life is treating us so-so. A couple of contracts are approaching the end and after speaking with Marco we concluded that we won’t be doing contract work for a good while. We have too many good stuff right now to work on that has caught way too much dust.

Looking back over the past few months, a lot of what we did was neglected because of contracts. They were alright in a way, some for the money, some for the knowledge, some for something else. But unlike our own games, there’s always a part that is missing, regardless of how good the project is. We feel that has to stop and that what moves us forward is our ability to pursue what we want: pride and happyness.

I also feel that both can go hand in hand with stability and stability is what we found in the past months. We need to step up and do our thing. We need to improve what we did for us.

Project wise, that means that we have to put Hajime on FGL, we have to decided what we want for M:A:D and we have to have time for our most promising game. Code wise this means that I have to reflect if we want to keep Bold Pixel public considering that the current version suits our needs more than it suits the initial user friendliness. I strive to keep things simple, to impose convention over configuration as a standard. Right now I’m not that sure that this will fit developers needs to the point that BPE is helpful.

We’ll see about that in the next couple of weeks. Thanks for reading and the therapy session.

Vlad out!

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