CutJS – Fast 2D HTML5 rendering engine for game development

by shakiba • 12 years ago

47 49 12 years ago

polskibus• 12 years ago

The approach reminds me of React in terms of keeping entire state aside from the DOM.

Of course it is much older than React, but you can see it performs very well and is suited for things other than HTML elements.

zerr• 12 years ago

Nice, but "Fast" - compared to what?

shakiba20• 12 years ago

Thanks! Fast enough for game development >= 60fps

Check out http://piqnt.com/o/

camus22• 12 years ago

so you claim your engine maintains 60fps whatever the code is thrown at it right?

IanCal• 12 years ago

That game judders and skips at times, I'm concerned if current "fast" HTML5 games are simple 2d games that perform badly. Even the asteroids game has perceptible little jumps. It's asteroids! It's one of the simplest to render games there is.

varg• 12 years ago

Very nice! ... was looking for something like this for some experiments, thanks.

shakiba20• 12 years ago

Thanks!

illicium• 12 years ago

new concept called pinning introduced instead of styling

It's just a scene graph.

shakiba20• 12 years ago

Pinning is about positioning variables, not graph structure.

aviraldg• 12 years ago

A scene graph is a scene graph is a scene graph. Whatever you call it.

Also, it looks like the pinwheel demo has an error. I suggest you add one of the more advanced demos along with source code on the intro page. Just looking at the first few demos I felt it reimplemented stuff that's already possible with CSS, but it looks like it's capable of much more (the last few demos)

Jare• 12 years ago

I couldn't understand exactly how it is supposed to work. Is it about defining anchor points in both parent and child (what you call "align" and "handle"), and then an offset from that?

throwaway15213• 12 years ago

A CutJS app consists of a tree of nodes, each node is pinned (transformed) against its parent and have zero, one or more image cutouts. Image cutouts comes from either image textures or Canvas drawing.

Won't SVG achieve the same thing?

shakiba20• 12 years ago

Yes, it has inspired me, but CutJS renders to HTML5 Canvas to be usable in game development.

olegkikin• 12 years ago

Why not WebGL-based?

pjmlp2• 12 years ago

Most likely because they also want to target mobile and system browsers don't allow for it.

shakiba20• 12 years ago

Exactly that's right, WebGL needed 2D fallback anyway.

kevingadd6• 12 years ago

Note that most canvas implementations on mobile are not hardware accelerated, so you're not getting all that much for your trouble. ;/ WebGL on mobile performs much better than Canvas on mobile for configurations that support both, just like on desktops.

shakiba20• 12 years ago

When I started it 2D was enough for what I was trying to achieve, it is also both easier to use and more supported. However WebGL may be added in future, but currently it is a costly development effort for me.

jablan2• 12 years ago

I know nothing about game development nor 2D/3D graphics, but why does an HTML animation of an airplane flying has to pin my i5 core to 100%?

martinml• 12 years ago

You probably don't have GPU acceleration enabled/supported in your browser. For example, if you use Chrome, check about:gpu.

jablan2• 12 years ago

That's true (thanks), but anyways, it seems to me that a simple animation should take only a fraction of a modern CPU's (or GPU) power. Is the engine calculating more often than what's needed for 60fps or whatever refresh rate our eyes need to be satisfied?

dikei2• 12 years ago

Yet another canvas manipulation library, just like fabricjs, kineticjs and easeljs

Kiro• 12 years ago

What's your point? Also, this looks like a new approach.

dikei2• 12 years ago

I don't think this approach is new. Scene graph structure has been used for a long time, and those libraries also make use of scene graph or allow you to use it.

mycounty• 12 years ago

Does it support high DPI (retina) resolutions?

shakiba20• 12 years ago

Yes, just use a high res texture and set imageRatio with texture definition.

See http://piqnt.com/o/ It is open source and available for iOS.

nacs• 12 years ago

One of the best 2d rendering engines I've found is Pixi.js ( http://www.pixijs.com/ ) which uses WebGL with a canvas fallback. Also works great on mobile.

Theres another framework that uses pixi for the rendering but adds physics, sprite support and sound/input managers called Phaser ( http://phaser.io/ ), also open source.

shakiba20• 12 years ago

If you like Pixi/Phaser you will love CutJS! Using CutJS is far simpler and you can use whatever physics and sound library you like. There are P2.js, PhysicsJS and SAT.js examples in repo. For sound you can use Howler.js, SoundManager, etc.

kevingadd6• 12 years ago

'Fast' is a poor descriptive choice for a library that was clearly written without attention paid to CPU performance characteristics, GPU performance characteristics, or the nature of modern Canvas implementations.

EDIT: A quick glance at the sample game 'O!' in the chrome profiler shows that it is triggering a garbage collection roughly every second. Pretty bad for a game with such low scene complexity and rendering complexity, and those pauses may be long on a mobile device.

Based on a casual review of the source code (which I'll note is quite readable - good job!), here are some obvious problems that probably need to be addressed, both in terms of actual performance and code quality.

Don't render the scene in graph traversal order; doing so ensures that the number of graphics state changes (shader, transform, texture, etc) is as high as possible. Most game engines render using a more sophisticated algorithm where your drawing operations are ordered (as possible - obviously layering has to be preserved) by graphics state in order to minimize overhead.

For some documentation on this approach, see articles like http://realtimecollisiondetection.net/blog/?p=86 I've been using this approach in my games for years and it produces a huge measurable performance improvement on virtually all modern architectures (even canvas, though it's less significant there)

The tickBefore/tick/tickAfter architecture is particularly suspicious, as is its use of poorly-scaling algorithms/primitives like Array.splice. Usually this sort of thing is more clearly and efficiently handled by having an ordered set of operations (typically represented by a linked list, a heapqueue, or an array of priority-value tuples that you sort once per frame).

I see frequent references to Cut.Pin.prototype.absoluteMatrix and .matrix. I will note that these don't appear to create garbage - which is great! - but they silently mutate a shared Matrix instance which means that it is very easy for a library consumer to end up with their state corrupted - if you store the result of absoluteMatrix, then modify the state of a Pin, that matrix will suddenly become corrupted. Sadly the code appears to make no effort to warn users about this.

You're not using any type hinting (i.e. | 0, +) which means that JS JITs will have to work harder to figure out whether given values are integers, floats, or something else. This results in JIT recompilations, less efficient in-memory representation, and in some cases results in floating point/integer values being boxed instead of stored efficiently on the stack/heap.

You mix different types in some of your slots (for one example, Anim._time is both 'object' and 'integer') which prevents optimization in most modern JS runtimes. This can have a catastrophic impact on performance in some scenarios, so you should avoid it if possible. A good way to replace a null/integer pattern is to have an integer that's always an integer, along with a hasValue boolean - this is how nullable primitives work in C#, for example.

Some of your non-initialization code uses temporary object literals - this.pin({ ... }), this._next = { ... }, etc - which is a recipe for bad performance and GC pauses if you're doing it during updates or rendering operations. It's not immediately obvious to me whether you could optimize this out easily, but you should make sure these temporary literals are not being created in large quantities.

You have many functions containing throw statements and a few containing catch statements. In most JS runtimes these both prevent optimization of the function body. You can solve this by hoisting the throw into a utility function (In JSIL I have a 'JSIL.RuntimeError' function that just does 'throw') - this allows the function to be optimized even if the throw-function is not optimized or inlined. When you have a single throw statement in a complex high-traffic function this can matter a lot.

You appear to not be validating or properly type-casting the inputs you pass to canvas.drawImage, which will impair performance and result in runtime errors. I can tell you've already run into problems with this since your drawImage call has a try/catch wrapped around it (YUCK) - the right solution here is to read the spec (that more or less clearly specifies the expected types and constraints for drawImage), and then make sure your code satisfies those constraints. It will be much faster and more reliable if you do so.

It appears that you may have many scenarios where you call drawImage with a source rectangle. This tends to be poorly-performing in canvas implementations (due to deficiencies in the spec), so if you want that to be fast for source rectangles that don't change, you should cache the source rectangle in a unique canvas so you can draw without source parameters. Typically source-rect blits can't be batched at all (i.e. one hardware draw call per blit) so this makes a big difference.

I'm sure there's more, this is just the result of a quick skim of the code. Feel free to contact me if you have more questions. You can identify many of these performance problems by reading specs and using things like Chrome's profiler and Firefox's SPS and JIT Inspector profiling tools.

I'm a huge fan of people sharing their libraries and engines with the world, but if you're going to spout superlatives you need to be prepared to back them up. Otherwise, people who don't know better will be misled by your dishonesty and end up having their efforts at using your tech go to waste when they have to port to something better.

shakiba20• 12 years ago

Thanks a lot for code review, I'm reading, but you have made many unjustified claims and based on results I would say your conclusion is not valid.

You have also made personal attack ("your dishonesty"), probably because of your own competing library (jsil.org).

kevingadd6• 12 years ago

Feel free to ignore the unsolicited advice on how to improve your software from someone who's been working on games and game engines for 10 years.

I ran your sample under a profiler and saw obvious problems with CPU and memory performance, and there are obvious problems with GPU efficiency based on your rendering model. This is not subjective; profiling is objective.

P.S. JSIL doesn't compete with your library, it's a cross-compiler. Are you angry because I gave a specific example of how I used one of the optimizations I suggested, or just because I'm pointing out that your website is dishonest?

EDIT: I shouldn't have to point this out either, but saying 'this text you wrote is dishonest' is not a personal attack. It's an objective criticism of your writing. Saying 'it's dishonest to call this library fast because x' is also not a personal attack, it is an objective criticism of your code.

If I called you a liar or a dishonest person, that would be a personal attack. I have not done that. I could certainly make that claim based on your argumentative style in this thread, but I shall not.

shakiba20• 12 years ago

Regarding you technical points:

Yes, there is an issue with O!, it makes too much garbage, it should be corrected.

I guess your point is to store depth of a drawable instead of traversing the tree? I'm not sure how faster it can make the entire rendering process.

tick(fn) to register fn is only called during initializations (not every frame), it doesn't matter how it is implemented.

Instead of pin({}) you can use pin('name', value) or simply reuse your {} object. I don't see any problem with "_next = {}" where it is used for creating tweening.

Without type hinting it is still fast enough, but good idea.

Thanks for your point about "throw", however I'm not sure functions having "throw" really need to be optimized, but I will consider that.

absoluteMatrix is only for internal use, and I have not documented it yet, but it is what it is and is only updated on ticks for performance reasons.

Thanks for your point about drawImage try/catch.

I'm not sure how drawImage with source params is optimized across different platforms so for now I have let it be as it is. But I agree with your point.

There is obviously a lot to make it run faster but the point is to find bottlenecks which really matter. For example in most case the bottleneck is the physics engine not rendering engine at all.

Also if you notice you can see I have done a lot to make it fast, for example using lots of timestamps (ts) and monitors (mo) to avoid unnecessary calculations.

Anyway feel free to fork it and change anything to prove that I'm wrong! I will appreciate that!

shakiba20• 12 years ago

I compared O! GC with few other HTML5 games, it seems that GC frequency is normal with high number of game objects.

CutJS – Fast 2D HTML5 rendering engine for game development

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