How do you wrap a 2D image around a sphere? Well, the most familiar way to me is what 3ds max calls spherical mapping; you’ll have seen this if you’ve looked at a 2D atlas. The top and bottom poles of the sphere get a much larger area of the image than the middle of the sphere. Without correcting for this in some way, the top and bottom seem very pinched. I found a way of correcting for this, for a (horizontally tileable) texture in Photoshop. You can download a little action I made to help with this here. I’ll try and illustrate what you get from it with an image:
Top left – front view of sphere’s geometry with yellow UV seams at poles; top right – UV layout; bottom left – a cheap 2D grid texture I photoshopped together using my action; bottom right: the resultant sphere with texture applied. Although the grid on top and on the sides doesn’t match up, at least the scale is relatively consistent, which for most textures will be the most obvious thing if standing out.
Another way of mapping spheres, with less distortion, is using a cube map. This is just 6 images representing the positive and negative of the 3 axes – front, back, left, right, top, bottom. I’m probably going to use this method for a static “spherical” environment of a star-field, to indicate far off, where there is no geometry. It’s very cheap on modern graphics cards, and you can generate them in 3ds max easily using an existing environment. Here’s a quick test I did in the engine:
The cube map starfield was created in about a minute using a pflow system in max. It is apparently possible to generate a “real-time” cube map starfield texture procedurally, but I doubt my skills will be up to it in the near future. I’ll probably just create something prettier in max and photoshop, or maybe not use cube maps at all and go with pure geometry.
In the above image, the planet is a geosphere (triangles and no geometric poles) with spherical mapping using the method above with a PS generated texture. Obviously the lighting and shading are really dull at the moment. The vertical poles look pretty good, except when the LOD mesh kicks in – probably a UV interpolation issue. Not yet sure whether to go with procedural planets, moons etc, or bitmaps. I’ll leave it to when I really want to overhaul the graphics!
I’ve been using Ogre for a few days now, just going through the tutorials on the website and messing around, and I really like it. After the pain of programming a uni project directly in OpenGL, I was kind of dreading how much work it would be just to get a model into a real-time renderer. As an analogy, imagine wanting to cook a nice meal, and having to build the oven first – you know what you want the oven to be able to do, but actually going about it is a slow and painful process.
However, with Ogre 3D, the oven is built for you! If I don’t want to, I never need to go into quaternion maths, building a scene hierarchy system, frame listeners or any of the other complex engine necessities. After years of using 3dsmax, I found the Ogre workflow really simple and straightforward. There are lots of nice features and it seems robust. It is not too bloated in my opinion either – although the set-up process was rather long. The tutorials on the wiki website are really easy to read and learn from, although one was unable to compile on my computer. http://www.ogre3d.org/tikiwiki/tiki-index.php?page=Tutorials
Here are some screenshots of the demo scene I just made (having done Tutorials 1-6), using some example media and my own ships/ space-station:
You can read the code I wrote to create the scene shown in the screenshots here: http://www.evernote.com/shard/s121/sh/58d7c731-1507-4e4d-9e3d-8c9b14ef2005/71b5b5d250ca72c7173b8478e5b66395 – there’s exponential fog, texture shadows, a spotlight, a skydome, and some C++ structures like for loops to get me back into the flow! If you know some C++ and are somewhat familiar with making 3D graphics, I think the code’s pretty short and easy to read.
The structure of getting models into the engine takes some getting used to. There is a human-readable .scene file (which can be exported from Max, Maya, Blender, etc) and a dotSceneParser class. What this means is that scenes can be altered from within the .scene file, .mesh files and .material files without you having to recompile the source code. It’s amazing that you can use Max as your game editor almost, placing lights and objects, without having to constantly recompile your C++ code!
Here’s a screenshot of the “Easy Ogre Exporter” open-source Max plugin, http://www.ogre3d.org/tikiwiki/Easy+Ogre+Exporter, which is a really nice and simple way to get max scenes into the .scene format:
I had a really enjoyable few days taking it slow and learning all about Ogre – I don’t want to get disenfranchised by jumping in to making the game too quickly and doing everything wrong. Also I bought a load of expensive computer parts to make a new system, which will speed some things up a lot compared to working on my laptop – compiling and running the game takes about a minute, and those minutes sure add up. Hopefully I’ll start making the actual game soon though.
I’ve been trying to set up the OGRE 3D engine for the last couple of days (you can read more about it here: http://www.ogre3d.org/tikiwiki/tiki-index.php?page=Getting+Started), and finally, after failing to build it from source, and install the Eclipse SDK, had some luck with Visual Studio 2008 – the default solution!
I might actually write most of it in Eclipse because I loved the features such as clever highlighting, version compare when I was writing Python scripts in Maya using it. I guess I’ll have to get used to Visual Studio though, because it is painful going through the Ogre installation process. I don’t want to try it again if I don’t have to!
It was the best feeling getting the sample browser file to compile after hours of failure on many fronts. I spent an hour absorbed in the samples in the engine, which demonstrate all kinds of pretty new features that the best games today have, and some that I’ve never seen (Real-time Julia fractal 3D volumetric textures?). It’s nice that you can switch in-game between OpenGL and DirectX as well.
It’s great being able to see the FPS impact for every feature and effect – I never knew bloom would halve the frame rate. The whole demo has given me the confidence that it’s possible to create a really spectacular game using the engine, so I’m excited. The thing now is putting in the time and effort! I have a lot to learn; as well as the book I mentioned in the first blog post, there’s a brilliant website that feels like exactly what I need: http://www.altdevblogaday.com.
I’ll try and update again soon with some programming tests.
Here are a few prototype ships for the game. I tried to keep everything quads (for unwrapping and zbrush sculpting mainly), and each object as few separate elements as possible. The poly flow is a bit awkward in places, so they may need to be scrapped completely in future. Each ship is between 300 and 700 polys – obviously future iterations might be higher detail, but I’m thinking it might be possible to optimise this game for mobile devices – assuming I finish it before phones come with graphics cards.
I’m not sure on the limitations of the engine because I still haven’t decided on an engine. I’m looking strongly into Ogre 3D, because it’s free and open source, and shouldn’t take too long to get to grips with the workings of the useful features (unlike something like Unity I presume).
Render done in 3DS Max/ Mental Ray, with generic ceramic material from autodesk. The distances between ships aren’t equal, so shadows look a bit weird. I think the ships should be roughly around this relative scale. The bottom row is just the ships above, rotated 180 degrees around vertical axis so as to get a good view.
This blog is an account of developing a 3D PC game. I intend to work on it (the blog and the game) over the summer, which for me starts in 3 weeks when my exams finish. Blog posts will probably not be regular – hopefully that will be due to my addiction to developing the game rather than a lack of progress!
The game is a smuggling in space simulation. The majority of the game will be flying a spaceship in 3rd person. The controls will be keyboard and mouse based, and intricate enough to be enjoyable to fly and fight. Visual design will be semi-realistic futuristic (like mass effect, star wars, sins of a solar empire) but as I am only one person, the 3d art quality may have to be sacrificed to allow me to concentrate on programming.
The programming will take up the majority of this blog and my time. I would like to use C++, but regarding game engines/ APIs, I haven’t made a choice yet. I am tempted to write systems implementing OpenGL, but this may be too much work, so I will look at other engines as well. I don’t have much experience at all, and am trying to get to grips with this book, which is fantastic but a slow read for me: http://www.amazon.com/Game-Programming-Gems-Series-v/dp/1584502339.
Please get in touch if you have anything to say, including ideas for features, opinions, or just telling me I’m doing it wrong! Thanks for checking this out,