Spore Cute Creatures

[Rosita Westhouse]

Lately I\u2019ve been dreaming about new energies and creatures that want to be pulled into this world. In my dreams I usher them through portals, create havens, give them voice. Last night I met the cutest creatures made from consciousness spore prints, called soul prints. Here is a distant relative from a hybrid kingdom who wanted to meet you.

Psychic art co-created with Midjourney and voiceover by Speechify.

I had a vision of bathtubs floating in space. It was before birth. Before I took this form. My soul tribe and I were disembodied spirits bathing in a row of cosmic bathtubs, waiting to be born. This is where we concocted our personalities \u2014 which is different from our consciousness or soul. We each sat in our own bathtub like cauldrons \u2013 adjusting the temperature and flow of the starry water \u2014 adding a little bit of this and a little bit of that \u2014 until we were just perfect for the life that we chose. We know we are not our personalities, we are the bathers in the cosmic bathtubs. Our personality is just a layer \u2014 a residue that we bathed ourselves in. It can always be washed off.

With Spore you can nurture your creature through five stages of evolution: Cell, Creature, Tribe, Civilization, and Space. Or if you prefer, spend as much time as you like making creatures, vehicles, buildings and spaceships with Spore's unique Creator tools.

With more than 100 new cute and creepy items at your disposal, you have even more power and flexibility to build the perfect creature. Create grotesque creatures with villainous mouths, tuberous eyes, and thorned plates, or go cuddly with big batting eyelashes, cute paws, and adorable details. You can mix and match 60 new parts in all for truly unique looks. Then apply one of 48 new paint styles, and bring it all to life with 24 new animations. And don't forget to publish your new cute and creepy creatures to share them with the world!

This page is intended to be a sort of liner notes for my contributions to Spore. It's a place for me to write up miscellaneous development comments about the parts of the game I worked on, while they're still fresh in my mind. I think the game had over 80 people working on it towards the end, and it was in development for more than 5 years, so basically everything in the game was touched by more than one person and was a team effort. Given that, I will strive for inclusion and accuracy, and I will only talk about systems to which I made substantial contributions. If I've left somebody out or made a mistake, I apologize; please email me and I'll correct it immediately.

A Brief Note on Game Credits This page could be seen as augmenting the game credits[1], like what you'd get if you could click on the names to get more information. I think credits are very important for game developers, our industry, and the art form[2]. Although assigning credit is a bit tricky because large-scale game development has a lot of subtle, overlapping, and often blurry responsibilities, I still think it's interesting to have rough descriptions and color commentary of the major things each person worked on. This is my attempt at this for my contributions, before I forget the details. I hope more developers put up pages like this for the games they work on.

Almost all of my contributions center around the creatures, and helping to bring them to life for players. My favorite moment in the game is when you first attach a leg or arm or mouth to the torso in the creature editor, and your creature comes alive and turns to look at its new limb or roars with its mouth. It's great to watch players be delighted by something they just created.

In most cases I'm limiting my discussions to the specific code and tools that I contributed to directly, which leaves out descriptions of a lot of the incredibly important and groundbreaking work other people did on neighboring code, whether higher level, more player facing aspects of the code, like user interface and gameplay, or lower level systems stuff like resource management, threading, rendering, and the like. It also leaves out the contributions of the awesome artists who used the [sometimes cantankerous] tools and systems.

The first thing I worked on when I started on Spore (in October, 2003) was the creature skin. Unlike games with fixed characters, like a James Bond or Lara Croft game, or games with parameterizable meshes, like the Sims or City of Heroes, Spore has to generate the entire mesh on the fly as the player makes the creature. While a typical game's fixed or parameterizable character mesh might be worked on for days in a 3D modeling tool like Maya by a professional game artist, Spore needs to regenerate the skin in real-time as the player deforms the torso and attaches and detaches limbs. I chose a blobby implicit surface (sometimes called metaballs) to represent the skin.

All of this skin paint development was done in tight collaboration with Spore's Art Director Ocean Quigley. We worked closely to figure out which degrees of freedom we needed to expose to give the creatures convincing organic skin, and how we'd fit it onto existing 3D hardware. Ocean has a detailed post about the skin paint system on his blog, and one of Andrew's SIGGRAPH 2007 Technical Sketches discusses skin paint as well.

Texture Charting As mentioned above, for a normal game, the character mesh is fixed early in the process, and that mesh is then charted (also called "uv'd" in reference to the use of 'u' and 'v' for texture coordinates) to create texture coordinates for all the triangles in the mesh. The final set of texture coordinates is called a texture atlas. Intuitively, we flay the 3D mesh apart, like skinning an animal, until it lays flat on a plane. There are mathematical theorems discussing the difficulty of doing this with minimal distortion, and the plethora of map projections[4] shows there's no "best" way to do this, and so artists will adjust and tune the mapping while the character is being created, until they're happy with the result. This might take a few hours or a day.

By contrast, Spore needs to create a texture atlas almost instantly, because the player can modify the mesh and then go into the editor's Play Mode or Paint Mode and see the results immediately. I wrote a very simple but optimized charter that does a really crappy job compared to a professional artist, but it does the job in 10 milliseconds on our minspec platform. Here's an example of an atlas produced by the charter:

Notice all the individual triangles at the bottom, and the wasted space. You can probably determine the algorithm if you look closely at the two images. The code starts on a random uncharted triangle, then floods outward as it finds neighboring triangles facing in approximately the same cardinal direction in 3D (meaning down the +x, -x, +y, -y, +z, or -z axes). When it can't find any more uncharted triangles attached to the current group and facing the same direction, it projects the group flat onto the plane of the current axis. This guarantees bounded distortion. After charting all triangles, it packs the charts into the texture atlas by sorting them by bounding box size, and then packing the bounding boxes of the charts in 2D texture space in a zig zag manner.

This texture atlas is incredibly well packed and distributed; all of the texels are used with no wasted space. Ocean once quipped that he'd fire any artist who made a texture atlas as bad as that frog's map. I replied that it was indeed a poor quality atlas, but it was maybe only 10 or a 100 times worse than a human might make, and it was created about 36,000 times faster, so my code is still ahead by a factor of 400 or so! Plus, it's quite difficult to squeeze a professional texture artist into each shipping game box. That said, the poor packing does have some impact on the final result, because wasted texels means less apparent texture resolution for a given amount of texture memory used, and lots of texture seams means both slightly bigger meshes because of lack of texture coordinate sharing and potential for visible seams on the skin. It turns out we didn't need the charter to be quite as fast as it currently is, so Henry and I mused about how to trade off a little bit of speed for better charting and packing, but it was unclear how to do this in the development time we had left. The high end techniques in most graphics research papers about texture charting take far too long for our use case, usually on the order of seconds or minutes[6].

The key difference between a Spore creature's texture atlas and a fixed game character's atlas is a human artist will paint into the latter, so it has to be made from recognizable pieces and it has to be coherent; individually charted triangles make no sense when you're painting into a map directly in Photoshop. Because Spore uses a procedural paint system, only the computer ever needs to paint into the texture maps for Spore creatures, so as long as the code can figure out where things belong, it's okay.

Lowlevel Texture Painting At the lowest level, the paint system renders multi-channel brush textures into the creature's 2D texture map. The initial prototype for the skin paint system was a "3D paint" system, allowing artists to use the mouse or graphics tablet to paint directly onto the creature mesh with a palette of brushes. At the time I was developing this code, all the existing 3D paint applications, like Maya and ZBrush, used really clunky projections that just didn't feel right. I took what I thought was the simple approach: raycast the mesh to find the brush's hit location, flood fill out on the mesh using the brush size to collect all the triangles hit by the brush application, and then render into the texture using the uv coordinates as the draw coordinates, the 3D coordinates as the texture coordinates, and the brush as the texture, while the texture matrix set up the brush's angle in 3D. I also generated "skirt polygons" around the actual mesh triangles in both 3D and texture space, and these were added to the collection of hit triangles if necessary. This avoided seams while painting, since a chart edge would have data beyond it when the texture resampler fetched neighboring texels for bilinear resampling[7]. Finally, the texture was dilated so mipmaps would not show seams. All of this was hardware accelerated, of course, so it was silky smooth. It worked great, felt completely natural, and the artists loved it. Since then, most of the professional paint apps have adopted similar approaches as well, thankfully.

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