I noticed this (the original code, and your implementation) seems to only describe the "state of feelings" for a simulant and how they generally only get worse over time. I'm now keen to see the code that then provides direction and action for the sim based on this state; e.g. "I'm feeling hungry, I should eat, what should I eat?" and the process that determines what it should eat - and how to go about it. I know The Sims employed more than just A*-towards-nearest-unoccupied-food-source, but what makes a Sim choose hamburgers from the outdoor grill over making dinner in the kitchen?
This demo (starting at 13:06) shows how the SimAntics visual programming language works, and how objects publish advertisements for their available actions (which show up on the pie menus that the user can select, or which the characters can autonomously choose to perform).
Advertisements appeal to characters based on their current motivations (feelings, hunger, etc), their distance from the object, their relationship with the object (so you prefer to sleep in your own bed), and SimAntics scoring functions that can perform arbitrary calculations.
Then it shows how all that works together in the "Food Chain", a complex Rube Goldberg device comprised of many different objects, that compels characters to perform the many sequential steps required to prepare and eat food (when then compels them to poop, which makes them need a shower, which makes them tired, and so on).
The main loop of the "autonomy" algorithm that decides what to do next (if you don't tell them what to do) searches for the top several advertisements with the highest score, and then chooses randomly between them. If they always chose the top scoring best thing to do, then their lives would be too mechanically optimized, lacking in whimsey and spontaneity, and anything the user told them to do would deviate from the optimal path, making their lives less efficient, more miserable.
So for better game play and happier users, we randomly dumbed them down a bit so they needed the user's guidance to have a better life (but we didn't make them so dumb that users couldn't fuck up their lives even more, either).
> If they always chose the top scoring best thing to do, then their lives would be too mechanically optimized, lacking in whimsey and spontaneity, and anything the user told them to do would deviate from the optimal path, making their lives less efficient, more miserable.
Couldn't they add a "monotony" factor to the SimMotive struct that increases as their daily life becomes too uniform, which in-turn leads to greater overall unhappiness if it's too monotonous, or greater overall stress if their days become entirely unpredictable?
The trick of optimizing games is to off-load as much as the simulation from the computer into the user's brain, which is MUCH more powerful and creative. Implication is more efficient (and richer) than simulation.
During development, when we first added Astrological signs to the characters, there was a discussion about whether we should invent our own original "Sim Zodiac" signs, or use the traditional ones, which have a lot of baggage and history (which some of the designers thought might be a problem).
Will Wright argued that we actually wanted to leverage the baggage and history of the traditional Astrological signs of the Zodiac, so we should just use those and not invent our own.
The way it works is that Will came up with twelve archetypal vectors of personality traits corresponding to each of the twelve Astrological signs, so when you set their personality traits, it looks up the sign with the nearest euclidian distance to the character's personality, and displays that as their sign. But there was absolutely no actual effect on their behavior.
That decision paid off almost instantly and measurably in testing, after we implemented the user interface for showing the Astrological sign in the character creation screen, without writing any code to make their sign affect their behavior: The testers immediately started reporting bugs that their character's sign had too much of an effect on their personality, and claimed that the non-existent effect of astrological signs on behavior needed to be tuned down. But that effect was totally coming from their imagination!
The create-a-sim user interface hid the corresponding astrological sign for the initial all-zero personality you first see before you've spent any points, because that would be insulting to 1/12th of the players (implying [your sign] has zero personality)!
Most likely you can infer a really complex set of events from this logic. For example, perform a "dice roll" while at a certain level of hunger (similar to how there's two dice rolls in the linked code that can cause the sim to freak out if stress goes too low). Additionally, the type of food can be inferred from the severity of the sim's state and time of day (e.g. snack vs breakfast vs dinner, etc).
All these "tricks" together, combined with a human's tendency to rationalize observations ("X must've happened because of Y"), can make for something that seems alive. :)
It's also quite mesmerizing to watch the relationships between the different numbers (e.g., the alertness value fluctuates, causing energy to either fall slowly or rise quickly), and all these layers add to the apparent complexity.
"combined with a human's tendency to rationalize observations" -- yes, that's a great explanation of what I meant by "implication is more efficient that simulation"!
One reason SimCity and The Sims were successful was because they were about domains that everyone has a lot of first hand common sense experience with, so players can richly and creatively fill in the gaps with their imagination. But SimEarth and Spore, for example, weren't as successful, because most people don't have first hand day-to-day experience with plate tectonics or space exploration to draw from.
The Sims only has a few things it can do at any point in time, but by rolling some dice and choosing randomly between discrete options weighed by dynamically calculated scores, the otherwise robotic obsessive compulsive behavior gets "dithered" into a smoother more organic stream of life choices.
I think of it like error diffusion dithering, where you only have a palette of 256 colors (or black and white, or an ugly web palette, or whatever), but you're trying to render a full color picture, so you choose the discrete color that's closest enough, then diffuse the error into the surrounding pixels. The human eye blurs those 256 colors into continuous gradients of smooth true colors, and the human brain then recognizes details that aren't actually there, which you can't see if you zoom in on the individual pixels.
The Sims diffuses the errors over time instead of space. For example, if you've gotten a bit grubby, you might wash your hands or take a shower. If you're nearby a sink and the shower is upstairs, then you'll probably just wash your hands, and you won't get as clean as you would have if you'd taken a shower. But then you're left over with some dirtiness that "diffuses" into the next time you wash somehow. If you only washed your hands, then you'll need to wash again sooner somehow, but if you took a shower, you get a longer period of time before your need to wash outweighs your other needs at the moment (or gets lucky thanks to dithering).
The Sims uses random numbers to choose between dynamically scored actions, to achieve "behavioral dithering" to avoid large scale patterns like "behavioral banding" (obsessive compulsive robotic behavior).
The art is in choosing a good spanning "behavior palette" of possible objects and actions, and tuning the scoring parameters and functions of each action that map the character's dynamic state to a numeric score.
The action scores can depend on your motives, and can attenuate based on your distance, and can take into account your relationship and past interactions with the object (so you prefer to sleep on the same side of your own bed instead of on the couch, and you're not allowed to play in bed with your enemies).
Action scores can also be unrealistically contrived to compel desired high level behaviors like leading Sims through the food chain (like a delicious carrot on a stick leading them around the kitchen and into the dining room to finally sit down and eat), or the irresistible "comeandseeme" object (shown in the video demo) that makes everyone in the house drop what they're doing and fawn over a newly born baby, or the diabolical "Crowd Sitter" I made for controlling large crowds of people at weddings and cult meetings.
When in play mode, you can turn a Crowd Sitter on and off with a pie menu, and it directs all people to sit down in front of it, or stand up facing it if there aren't any seats left. It has an effective radius of about 7 tiles (more now), with a quarter pie slice shaped footprint. You can strategically deploy as many sitters as you need, to cover all the seats you want people to sit in or areas you want them to stand (like rows of pews in a church or a circle of benches in a stadium). I made a special routing slot that has a maximum size 54 tile footprint (more now), based on the TV set's routing slot, but on steroids.
Dither is an intentionally applied form of noise used to randomize quantization error, preventing large-scale patterns such as color banding in images. Dither is routinely used in processing of both digital audio and video data, and is often one of the last stages of mastering audio to a CD.
The algorithm achieves dithering using error diffusion, meaning it pushes (adds) the residual quantization error of a pixel onto its neighboring pixels, to be dealt with later. It spreads the debt out according to the distribution (shown as a map of the neighboring pixels)
https://codepen.io/blixt/pen/ayyjpZ