BetaCairo: Cairo Wrapper, 0.1 Released!

[betajaen]

Hello again! Let me show you the 3rd* of the "Beta" free libraries; "BetaCairo".

Unlike BetaGUI, BetaCairo has one dependency, the Cairo library. Now let me explain it to the uneducated. Cairo is a 2D graphics drawing library which supports bitmap and vector drawing onto an image, as well as basic image manipulation, it also includes support for SVG and many other things, and apparently it's used in Firefox 3.0 for the new canvas tag. So it's pretty nifty.

So I've just made a simple wrapper so it can directly draw onto an Ogre Texture, which can then be on an entity or in the case of of the screenshot onto an overlay ala BetaGUI. The texture then can be updated as many times as you like i.e. an analogue clock or a push button.

How the above image was created is another amazing thing:

Code: Select all

mTexture = new BetaCairo::Texture("wee", 256, 256);

mTexture->fill(Ogre::ColourValue(1.0,0.65,0.65,0.1));
mTexture->drawLine(ColourValue::Red, 10,10, 100,100);
mTexture->setLineThickness(2);
mTexture->drawLine(ColourValue::Green, 100,10, 100,100);
mTexture->setLineThickness(3);
mTexture->drawLine(ColourValue::Blue, 10,46,100,100);

		
mTexture->drawRectangle(ColourValue(0.5,0.2,0.6,0.4), 190,20,50,30);
mTexture->drawBox(ColourValue::Black, 8,150, 100,60);
mTexture->setFont("Gill sans", 16);
mTexture->drawText("Hello Ogre3d.org!", ColourValue::White,10, 180);

mTexture->redraw();

Then used in a material:

Code: Select all

MaterialPtr material = MaterialManager::getSingleton().create( "WeeMaterial", ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME);
material->getTechnique(0)->getPass(0)->createTextureUnitState("wee");
material->getTechnique(0)->getPass(0)->setSceneBlending(SBT_TRANSPARENT_ALPHA);

Then used in this case in a BetaGUI window:

Code: Select all

mGUI->createWindow(Vector4(128,128,256,256),"WeeMaterial", BetaGUI::NONE);

And thats just the tip of the iceberg of what Cairo can do, and hopefully in many versions to come BetaCairo can do as well.

I'll shall be releasing version 001 of the source tommorow under the same license as BetaGUI, and in the same manner.

But I'm already wondering what some crazy Ogre programmer can mix BetaGUI and BetaCairo with; Vector Overlay GUIs. Oh my

Enjoy!

*BetaSound will be released once I get the kinks out of it.

[Wolfmanfx]

Looks really great & usefull...
i know cario from gtk+

[joshcryer]

Wow! Excellent job!

I think this was done before? But I like what you've done here. Thanks for the contribution.

[johnhpus]

I don't have any experience with Cairo, but just by looking at the example code you posted for drawing lines into a material I can already see this is going to be good.

[Game_Ender]

Do you use the accelerated features of Cairo? One of its upshots is the ability to use the opengl (glitz) backend and draw directly to an opengl context (texture?). Allowing much faster rendering. There GTK2 Cairo Engine to provide prettier Linux themes.

PS. Can you use a slightly better number scheme for this than you have NxOgre. You know, something like Major.Minor.Patch. Where the first Alpha/beta release all go in 0.x.0 range. Just a request. I am very interested in looking at this under the hood.

[joshcryer]

But I'm already wondering what some crazy Ogre programmer can mix BetaGUI and BetaCairo with; Vector Overlay GUIs. Oh my

You will be my hero if you can get this working. Seriously. InkSpace + Cairo + BetaGUI/Cairo would be so amazingly awesome. It would solve one of my biggest problems (not keen on CEGUI, and have been hacking my own for a long time now, always being put off by the task, but this would make it so much easier).

[Wretched_Wyx]

Holy smokes I've been in the cave too long again. BetaGUI + BetaCairo... I think I'll definitely play with this a bit. If it turns out to be easy to make vector based GUIs with this combo... Well I guess it will give me something to do that can actually pull me away from what I've been doing lately .

I've been wondering why it doesn't say "MVP" under your name... You've been rolling out some nice stuff lately, and of course the almighty NxOgre alone should be enough to earn that status. Though I guess you don't need it, we know who you are and the great additions to Ogre you've made .

Okay enough brown nosing. Do you have any cool features for later versions of BetaCairo that you can share? Also can't wait to get my hands on BetaSound, sounds really cool.

[betajaen]

Do you use the accelerated features of Cairo? One of its upshots is the ability to use the opengl (glitz) backend and draw directly to an opengl context (texture?). Allowing much faster rendering. There GTK2 Cairo Engine to provide prettier Linux themes.

I have tried, directly writing to a texture via Cairo but it comes out weird. I have the pixel formats correct, but with there is a required stride value which I cannot find anywhere related to the Ogre texture. So it comes out quite funny. So I'm just using a for loop now to copy the pixel data over, but I'm going to try again.

PS. Can you use a slightly better number scheme for this than you have NxOgre. You know, something like Major.Minor.Patch. Where the first Alpha/beta release all go in 0.x.0 range. Just a request. I am very interested in looking at this under the hood.

NxOgre uses the same system. We just don't use patch numbers.

I've been wondering why it doesn't say "MVP" under your name......

It would be nice, but I hear their private members bar can be quite noisy sometimes.

Okay enough brown nosing. Do you have any cool features for later versions of BetaCairo that you can share?

Yes! I want to get SVG working, and loading of images directly in. This alone would cover many many different possibilities of use, and even for newbies things like tachometers would be a few lines at most.


As for the BetaGUI/BetaCairo combo. SVG would be certainly the easiest way to implement it, but probably one of the slowest. But some definite fiddling is needed.

However I think I've decided (or someone has decided for me) on my project for the holiday break people!

[sinbad]

Beta-tastic.

[SunSailor]

Following the rules of this forum and the Ogre-project, I'd like to propose betajaen for MVP .

[DaCracker]

Following the rules of this forum and the Ogre-project, I'd like to propose betajaen for MVP .

Me too

[jacmoe]

I remember :wumpus: talking about Cairo and Ogre a lot, but never got around to it.
Kudus to you, betajaen!

I am, however, not going to use Beta libraries, ever!

Just kidding...

[betajaen]

I am, however, not going to use Beta libraries, ever!

Fine. I won't use your software either.

Just kidding...

I'm not.

[johnhpus]

Hah, well maybe your anti-endorsements of one another's software are purely in jest (and maybe referring to a joke I missed in another thread) but you guys might reconsider your posts. It's confusing unless you actually don't trust the code.

[jacmoe]

Beta, that's after Alpha, isn't it?
Beta and Alpha are generally what comes before an actual stable release.
Betajaen calls his libraries Beta_whatever, like BetaGUI, BetaCairo.
Pun intended - get it?

Anyway: I think this is generally awesome! Vector graphics and Ogre == Yummi!

[Falagard]

I can't endorse Betajaen for MVH, he's clearly the devil:

Username: betajaen
Joined: 18 Jul 2005
Posts: 666
Location: Wales, UK

Maybe after he posts one more time though

[betajaen]

I always get confused with him, I always say "Mate, you've got the wrong address!".

[paddy]

This is very good news. I had to write a very primative (ie unpolished) line/bezier drawing tool set and since decided to gut it for a quality external 2D lib, but haven't gotten around to integrating one with ogre yet.

Now I won't have to!

[betajaen]

Update!



There won't be a release today like I wanted, but I have some news.

BetaCario is currently in a library (BetaCario.dll) format, but if I can get the right license allow it to be directly imported into your project like BetaGUI or use it like the library. To meet the best of both worlds.

Second, there will be three sample/tutorials that are copied to your Ogre samples directory after compiling:

• BetaCario101: "Dynamic Textures" Image above. A working clock is projected onto the cube, the hands actually move around depending on the time of day, the grid on the floor is generated by BetaCairo too.
• BetaCario102: "BetaGUI". Using BetaCairo with BetaGUI.
• BetaCario103: "BetaGUI and BetaCairo to the extreme". Put BetaGUI windows onto meshes and using them, just like the Doom 3 computer consoles

Probably for the first time in Ogre history ever. These samples/tutorials are requires no external resources what so ever. All the meshes and images are generated for you, the boot up time is staggering.

[Game_Ender]

More technical questions. What cairo backend are you using for this? A custom Ogre backend?

[Wretched_Wyx]

That is so freakin' sweet... I can kinda tell from that shot that the generated textures are very clean, ie less jaggies than using your standard textures, and and I'm not referring to AA. Yet I still have to ask- how sharp are the textures BetaCairo is generating?

Also, does BetaCairo have built-in functionality to save the textures it generates out to file (ie png/svg)? I'm sure it wouldn't be (assumption) too hard to add that in ourselves if we needed to, just curious if it's possible out-of-the-box.

BetaCario103: "BetaGUI and BetaCairo to the extreme". Put BetaGUI windows onto meshes and using them, just like the Doom 3 computer consoles

That just put me in an infinite loop of pants wetting.

I can't endorse Betajaen for MVP, he's clearly the devil

*Oh you have no idea... Just last week he ordered a hit on my guinea pig because I wouldn't give him any cake. I managed to get him some cake before he followed through with it... but instead he had 3 of my fingers chopped off. Makes things much harder on the coding end, I'll tell ya. I won't tell you about the time I woke up with a horse head in my bed, because I jokingly said I didn't condone the use of NxOgre.

* For the very gullible, this is a total fallacy. Though I wouldn't put it past him...

[Praetor]

Ogre already depends on libraries that load (and save?) images of all sorts of formats. I imagine if Cairo can speak some intermediate language, even it doesn't have saving functionality, it can make FreeImage do it.

And I'm sure the sharpness will still depend on the resolution of the texture you are writing it to. But in that screenshot it indeed looks very sharp.

[Wretched_Wyx]

Good point about making FreeImage save the texture out to an image. As far as the the sharpness goes... I've always known SVG to be a vector image format. And I've always known vector images to be super sharp, and in particular SVG scales very nicely. So if you made a texture at a 512x512 resolution, and then scaled it (say, with BetaCairo?) up to 1024x1024, you wouldn't have a loss of quality or any jaggies or blurring, etc.

At least I'm pretty sure that's how it works. I don't have *that* much experience with vector formats, but enough to get excited about the crazy things you could do with this.

[Game_Ender]

Vector formats don't scale "very nicely" they scale perfectly to an infinite size. The only limitation is the size buffer you render them to. Cairo can save any cairo_surfrace_t to a png with cairo_surface_write_to_png you just need to make sure support for that was compiled in when you build cairo.

Has anyone found a good cairo + glitz tutorial?

[Vectrex]

Well I'm not sure how OgreSWF does it, but it can draw directly to the screen, bypassing the render to texture bit. It's really fast and infinite resolution. Maybe interrogate stoneCold?