Loads of LODs

Finally back to doing stuff. Another pile of work went in to doing this thing which should normally be invisible.

In the previous post I showed some automatic LOD generation, which is OK I guess, but doesn't do a great job all the time. For more control, you need to be able to import multiple versions of the same mesh which you have built by hand. The cylinder above is actually three separate objects which were created in Blender and imported from one file. The scales for switching between LODs were assigned automatically (based on the size of the faces in the objects), and are exaggerated here, again, for debugging.

So, that's working. Now just to check it works in concert with some other features, and then I can move on to... other things.

Creepy Purple Head Is Creepy

This took a lot longer than I hoped. This post is about level of detail. That's where you take out some polygons and simplify a shape, usually based on how far away it is from the viewer, to save your graphics card the trouble of calculating things for polygons which are so small they only cover a few pixels or less anyway. I've had spheres doing this in my "engine" for a long time, because for spheres it's relatively easy to calculate the appropriate low(er)-poly mesh or meshes. For general meshes though, the easy approach is to create a mesh for each LOD using external tools or by hand. I was thinking of taking an automatic approach to generating these meshes and calculating the appropriate view distances. This would, in my mind, save me the trouble of having to do this outside the engine and tune each model's selection of meshes. (It would also save me from the problem of how to handle shape keys on lower-poly versions of a mesh, although I'd probably just ignore that.)

So, after finishing up fog and transparency illumination in the last post, I noticed that my sphere LOD scales seemed to be a bit off, so I started debugging. That led to bug fixing, and that led to me starting to implement that auto-LOD-generation that I had been thinking about. Like I said, it turned out to take longer than I had hoped. Part of this was finding some reasonably fast and simple algorithm to implement, and part of it was discovering things like Blender had output a separate vertex for every triangle corner in my mesh, even though most triangles share corners with other triangles. This meant a detour to merge these vertexes so I could do a bit of topology analysis in the algorithm (also incidentally saving a bunch of memory after merging the vertex data, although I guess that's not such a big deal compared to things like texture memory).

The final effect is shown in the video above. It works... Ok? I guess? The effect is exaggerated for testing in the video, and normally the changes are basically invisible. I think simplifying material shaders for distant objects will probably be a bigger win (and I'll see if I can automate that too). But anyway, now you know how I spent the last couple of weeks and why clouds still aren't implemented.

Dramatic Sunset Lighting With Forward Scattering

It sort of has something to do with clouds, honest.

Among a bunch of under the hood fixes and additions over the past little while, I went back to my transparency and fog shaders. Both of these effects reference a 3D texture "illumination map" that I generate in screen space. The illumination map makes it possible for all the lights to at least have some effect on transparent objects, including fog. The original illumination map only holds the response of a directly illuminated sphere to incoming light, summed up for all lights. This would be appropriate for clouds made of fairly large particles, which is why I talked about dust in the description of the first video. Maybe blowing sand would be a better description.

Notice how the transparencies in this older video are black when viewed against the sun, and compare to the behavior of the same type of object in the first part of the new video above.

I also wanted to be able to simulate things like steam or water clouds, which, because they are made of smaller (and transparent) particles, scatter light forward instead of just reflecting it back. And I also wanted to support a mix of different types of cloud or transparency in the same scene. I've attacked this problem by rendering two illumination maps, the original, pure reflection map, and another which represents (mostly) forward scattering. (Right now, both maps are applied as-is, but I plan to make the response weighted by the transparent material in a later update.) This is what makes the transparencies shine when illuminated from behind in the top video, and gives the nice (if pixellated) murky sunset effect at the end of the video.

I was thinking of moving on to clouds next, but I could also implement an entire framework for visualizing and debugging the illumination maps, which would only take another week or two...

Mr. Blinky

Well, that certainly is a creepy purple vaguely head-shaped lump. This is a slightly more complex model than the non-descript pillar of purple from the last post, and it blinks. It has separate shape keys to close each eye, and an animation linked to both of them. It also has shape keys for opening and closing the mouth, but I haven't created the tools to pick and choose which animation or key I am manipulating from the game engine's UI yet, so I'm stuck just showing one at a time.

Anyway, things move along. Maybe some additional UI tools before I go on to the clouds...

Shape Keys

Shape keys, or morphs, or morph targets, are a way to control the shape of a mesh by having a number of different meshes (or targets or keys) with the same number and arrangement of vertexes, each of which represents a kind of target shape. Then, by adjusting a weight value you can use one or more of these shapes to influence the final shape. The video above demonstrates a very, very simple case where I have a big purple block, and one shape key attached to it, which is the same block with one side pulled out into an ugly protruding lump. By sliding the control on the lower left, I can run through an animation which makes the lump bulge out and then fade away (changing the shape key weight from zero to one and back again).

I got support for the shape keys themselves into the code last week, but I had to spend a bunch more time adding in support for UI controls and support for linking those controls up to the animation so that I could fool around with the weights in real time. (This is called testing in some circles.) Now that the basic support is in there, it should be a lot easier to set up other controls and debug tools from now on.

I know I said something about clouds last time, but I think the next thing I'm going to do is some more complete shape keys, e.g. a rig for animating a face or some such. We'll see how long that takes, and then I'll probably go back to work on atmospheric effects, unless I get distracted by something else.

Right, Then

So anyway, blogging is now completely forgotten, so I'm just going to use this as my random hobby diary.

I'm building a game, or game engine, or some kind of thing, using obsolete technology on old hardware, for the hell of it. It's fun, for me, and gets me weird looks from my wife and kids.

I have a vision for a kind of space game, a bit of KSP, a bit of Minecraft, but not really either of those things. And since it has space, and planets, I've been trying to make planets that look reasonably good for a while now. One feature that's been in a long time has been atmospheric scattering, based on an old GPU Gems article (here). Works well enough. Indeed, it was a real eye-opener about how much math I could do in the GPU, even on an older system, and get away with it.

A separate trick I picked up in some game development article I've forgotten about, is using the color of the sky overhead as the ambient light value. This makes the insides of shadows blue lit in the daytime and reddish at sunset, for example.

Now, when out in space the ambient light value doesn't take this sky overhead thing into account, which is correct if you really are out in space, since the sky should be black. There's still ambient light, but that's a problem for another day. Anyway, I thought it might be a good idea to simulate the ambient light on the surface of planets as seen from space. They should be illuminated by the sky as well as direct light from the sun.

Turns out, the effect is very subtle. You might even say invisible.

Never mind the light positioning and lack of clouds. Unless you know exactly what to look for (the area along the north edge of the Arabian peninsula is a little brighter, but that might be affected by other factors too), you would never notice.

On the other hand, even the additional math to do this doesn't seem to have too much effect, so I'll probably leave it in. See it in motion on my YouTube channel.

Now, clouds, that would be cool.

Eyebrows One Year Later

I was fiddling around and upgraded Blender to 2.71, and then, of course, I had to open up my old head-sculpture file to see if it worked. How about that... visible eyebrows. Perhaps some performance improvements have squeezed a few more polygons out of my hardware, or maybe I'm just forgetting how, exactly, it was broken. But anyway, looking back on it a year later it looks... kinda hideous.

Yeesh. I mean, it's OK, I guess, for an initial stab at something, by someone with almost no experience with these tools. But it's nowhere near what I wanted. One of these days I'll take another stab though, maybe at something similar, maybe at something else.

Ill Advised Posting

(I thought I wasn't going to talk about this. I guess I was wrong.)

So, the police officer who shot Michael Brown six times, was just doing his job, and almost half of white Americans think race is getting too much attention in the case. People are "playing the race card"? "Lawlessness knows no color"? What?

Even if Brown was shoplifting (which is not all that clear) or jaywalking, the penalty for these crimes is not death in the US, last I checked. The penalty for acting suspicious is also not death, but apparently a woman in the first article believes it is:

“An officer doesn’t have xray vision,” wrote Jennifer Hall, of Robertsville, Missouri. “He can’t tell if you have weapon or not until searched. So you act in a suspicious manner, we know what the consequences are.”

Seriously? If your white son was caught jaywalking and mouthing off, and was shot dead for it, that would be OK? Because we know what the consequences are for acting suspicious, right? Or is it that those people are lawless. Those people are criminals. Those people deserve to be treated with suspicion and executed if they step out of line? And those people just happen to be black?

We all set this fire. We need to own up to that.

Minimum Wage

The title is a reference to the They Might Be Giants song. Really. That's what I was thinking about when I wrote it.

The other day I reblogged this thing on Tumblr about Walmart earnings and the salaries they pay their workers. For the most part my pinko bleeding-heart liberal friends seemed to agree: Walmart makes $27 billion in profit in one year, they could pay their bottom million employees $10,000 a year more and still make a $17 billion profit. This situation and others like it illustrates the crazy imbalance of our economic system, in which a few specialists in e.g. financial markets are paid hundreds or even a thousand times as much as regular workers who do essential jobs.

There was at least one person, however, who took issue with the statistics involved, saying that it didn't seem likely that a million workers, almost half of Walmart's total employees (and they are the biggest single employer in the world, apparently), were scraping by on minimum wage.

Now, the original post isn't actually criticism of Walmart specifically, so much. The second half of the post makes clear that this is about larger issues with the system itself, and Walmart is just a symptom. Whether Walmart only has to pay $10,000 more to a hundred thousand employees or a million doesn't really change the point, at least in my mind. (Wikipedia figures for Walmart also suggest that it might make more sense to use the profits after tax, which is only $16 or $17 billion, depending on what year you're talking about.)

On the other hand, checking Walmart salary information that's publicly available does paint a picture that seems consistent with the original post. I'm just looking at the first page full of results, and there are some reasonable and even well-paid positions. (Want to do well at Walmart? Become a pharmacist!) But the bottom-tier jobs pay $8 or $9 an hour on average. Being generous, that's $18 to $20 thousand a year. The "Careers to explore" links on that page include "Overnight Stocker" at $19k a year, and "Sales Associate" at $18k yearly. That's well below the poverty line for a family of four.

From the results from that page, a little less than half of the jobs on offer from Walmart (2073 of the 4205 positions summarized) are hourly jobs that pay on average about $19 thousand a year. If this is in any way representative of the mix of positions in Walmart's 2 million employee workforce, then yes, roughly a million workers are making poverty-level wages working for a company that made at least $16 billion in profit in the last year, after tax. Even if the results are strongly skewed, we're still talking about hundreds of thousands of workers.

Then there's this article, in which statements from Walmart spokespeople themselves lead one to the conclusion that a bit more than half of Walmart associates make less than $25,000 a year. Statistics are easy to misuse, but whatever way I look at this, it still seems like a lot of people are struggling to get by while a very few reap rewards out of proportion with their contribution to the company, society, or, well, anything. So, to repeat:

You know, this ridiculous idea that a worker on Wall Street who earns tens of millions of dollars a year securitizing imaginary assets or doing high-frequency trading is worth 1,000 times as much as workers who earn tens of thousands of dollars a year educating our children, growing or serving us our food, throwing themselves into harm’s away to protect our life or property, that this difference reflects the true value or intrinsic worth of these jobs is nonsense.

I Said I Wouldn't Explain

That's the best image I could find. Well, no, actually, it's the first image I could find, which makes it the best. Click on the picture to go to the actual page.

That is a Japanese boxed lunch, a bento box. It has a picture (made out of something edible, I suspect) of a cartoon character on it.

Look closely. It is a rabbit, in a ballerina dress and tiara.

This is ありがとウサギ, the "thank you rabbit."

You could be forgiven for thinking it is, well, not exactly the most appealing character ever. You wouldn't be alone. The character was the subject of discussion on 2chan as to just how unappealing she, or it, was. This included the obligatory improved versions.



Much better.

But anyway, why? If you were in Japan, watching TV, any time after the March 11th quake, you know. This is why:

Click here

Immediately after the quake, there were no commercials to speak of. Slowly, the commercials returned, or rather, some commercials returned. The one linked above and a small selection of others from AC, all safe, inoffensive messages about being nice, were the only commercials, repeated sometimes three or four times in a row to fill air time. People actually complained that the "A~ C~" tune at the end was getting on their nerves, and the commercials were changed to remove it. You can find some pretty funny remixes on the tubes (and a lot of really stupid ones) if you look. None of them would make any sense either.

Everybody has seen this commercial, hundreds of times at least, in the last month and a half. It's to the point where seeing something like that almost makes me feel nostalgic, or maybe a bit sick. The idea of eating lunch with that damn rabbit on it is just...

Anyway, now I've explained. And it still doesn't make any sense.