How to approach procedural planets

[50gens]

A feedback on the first post

@Zahyyy

One of the problems is that the planets would not be dynamic, meaning that over millions of years, they would not change whatsoever (regarding things like erosion and tectonics)

If space stage takes place in a short amount of time such as thousands of years, (so no plane tectonics, no evolution, no generational ships, ftl travel) the planets can remained unchanged, with the exception of extinction events and terraforming acts. (what would you do in a million years anyway? how many technologies there can be to discover? the game would need to slow down if there is no ftl or there isn’t ascension)

We can still add a tool to space stage to simulate the future evolution in a planet, and it wouldn’t take too much computational power, because it is happening to just one planet (or however many you placed)

@50gens

Place a solar system in a time dialation field (evolution experiment)

Which would be a way to have this

@hhyyrylainen

releasing a tool that players can let run separately to generate a ton of planets which we can then distribute with the game

inside the game too.

@Zahyyy

we’re also going to more or less randomly pick the planet’s diameter, the tilt of its axis and the speed of rotation a) around its own axis and b) around the star

There are limitations to a planets diameter. It can’t be too large, because it would keep a hydrogen atmosphere, becoming a hycean planet or a gas giant. If the atmosphere blocks the sun, there can’t be photosynthesis on the surface, and if photosynthesis happens on the atmosphere, there is no access building material for cities. If it is too small, it would lose its atmosphere and wouldn’t have enough pressure for liquid water.

The speed of rotation around the star only depends on the distance to the star, which is limited by the goldilocks zone, not an independent variable that can be random.

@Zahyyy

Where the climate is appropriate, rivers will be added by simply picking a random place somewhere relatively high and by always looking for a lower place, they will either enter the ocean or end up in a dead end creating a lake.

Rivers or pre-river water can also be used to create terrain itself

Coding Adventure: Hydraulic Erosion

@Zahyyy

As I said, this system has some downsides. One of them is the fact that it disregards geological history completely. Another downside is the fact that it’s not dynamic and won’t change at all over the course of million years.

Animating erosion and plate tectonics would make planet features dynamic.

The planet would start flat when its crust first solidifies, and some time after that it would get covered with water. Tectonic plates, which are all similar at first, would move randomly, and in places they move into each other, they would rise up to create a continental crust, which is above water. In places they move away from each other, new oceanic crust would be created. In time, the oceans would get deeper and the percentage of land would increase*, but not forever because two lands can crush into each other too. Simulating erosion would keep the land shapes realistic, there wouldn’t be mountains that are too high and there would be large regions of land that have a low elevation, just above the sea level^[1], creating the second hump*. When sea levels increase, some of the continental crust would fall under the sea level, and deltas would turn into estuaries. Any geologic formation can be simulated the same way they appear in nature.

Having a planet that changes also has implications for seeds. In many games, you can enter a seed to create the same map again, but for that to happen in a realistic Thrive, the forces behind plate tectonics should be deterministic and erosion needs to give the same result every time. And even after that, you wouldn’t find yourself in the same continent when you start building cities if you didn’t spent the same amount of time evolving.

@Zahyyy

Also, as a bonus I’d like to mention is that we can use the same system we used for trade winds for oceanic currents, creating even oceanic biomes, which then can be converted into a patch map for the microbial stage. Which would be cool.

It would have been cool, but ocean patches don’t have anything to do with currents.

Abyssopelagic, bathypelagic, mesopelagic, epipelagic and coastal patches differ by depth. For “different” regions in the same depth, we can call each biogeographic realm a different patch. They differ by climate and whether the ocean surface has sand or rock. And they only exist for shallow waters.

The Biogeography of the Oceans

So something like the North America colliding with South America and seperating the tropical region of the Atlantic from the Pacific causes the species in the different sides to diverge, but unlike a land, an ocean current can’t restrict the spread of a sessile species that is adapted to a certain climate and create different realms.

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1. because that’s when the rivers slow down and stop eroding the land ↩︎

[HexapodPhilosopher (Disguised as a rock, until you get too close...)]

We would certainly want to have movements in the landmasses over time, but it would be best to avoid unnecessary complexity. There are some ways it could be done, though. For instance, using the height map created via Perlin noise, we could have regions marked as distinct land masses, perhaps by colouration. Then, every so often, we could have the height map altered by moving each region in a random direction, and overlaying the results. It would probably be a good idea to then have some erosion of the results. The Coding Adventures video you linked to is really good, but we’d need a much more efficient way of doing it.

The comment about the invariable planet orbit speed is quite right. If the average speed of the planet is higher, it will simply be orbiting further away from the star. We could have elliptical orbits, but these wouldn’t be necessary, and would be something that mainly affects the space stage.

[50gens]

@HexapodPhilosopher

We would certainly want to have movements in the landmasses over time, but it would be best to avoid unnecessary complexity. There are some ways it could be done, though. For instance, using the height map created via Perlin noise, we could have regions marked as distinct land masses,

I don’t think I described a complexity that is unnecessary, if realism is one of the goals of the game. The way the shape of the land changes depends on the collision of tectonic plates and erosion. We can add volcanism and meteor impacts to that list.

What does perlin noise represent? The changes in land shapes that happened before the game started to simulate them? Does the simulation start a very long time after the planet first forms?

@HexapodPhilosopher

we’d need a much more efficient way of doing it.

That is true. There needs to be a code that says how the elevation map changes after a certain amount of time, depending on the slope, and this code should replicate the results of the raindrop simulation. But I don’t know how that can be done.

[HexapodPhilosopher (Disguised as a rock, until you get too close...)]

The noise texture is basically a simple way of simulating terrain that’s already been shaped by planetary and cosmic forces. On Earth’s timescale, it would be from at least the 500-million-year mark (just before the first life develops). But, unless the player would have a view of the whole planet as it develops, there would be no reason to simulate the terrain immediately on the game starting. It would be unnecessary for the game to include such a planetary view, until the player’s species has spread across the world. If lifeforms can’t go onto land yet (and the player can’t view the whole planet yet), there’s no need to fully simulate the terrain on the land -it would just be wasting processing power and game time. A more basic simulation of land movements would be sufficient for the earlier stages, and then simulation of the terrain under sea, then at the coast, before covering the whole planet. Any areas without full terrain simulation could still have continental movements simulated.

As for plate tectonics and meteors, I think this would mostly be unnecessary for the game. Thrive aims at being a realistic simulation of the evolution of life. This would inevitably involve a lot of factors such as continental drift (with the number, size and spacing of continents shaping the chemicals in the sea at different points, and whether species become isolated from each other). However, simulating the shaping, wobbling and interaction of tectonic plates is a whole level of complexity that would:

1. require a whole load more time to develop,
2. take a lot more time to process, while the player sits and waits, and
3. make no actual difference to the gameplay once the loading has finished.

It would be something that’s nice to look at, and could be educational, but I think it’s a whole other simulation in itself.

As for meteors: having them simulated as a planet shaping force in general would probably not get into the game, for the same reasons. Having them as random events, though, would be great. And as the project develops further, I’m sure a lot of people will want to have mass-extinction events. It would be unrealistic for the evolution of life to not have any such things. I know there’s been talk of putting the Great Oxygenation Event into the game - which would be a mass extinction caused by life itself. Having a massive meteor hit the planet occasionally, with a huge impact on what life can survive would be a great addition. I’m not sure how this should affect gameplay, but it’ll be worked on in future. Also, having smaller meteors occasionally drop in near the player would be cool. If Lawk is turned off, they could even have new microscopic lifeforms in them!

With volcacoes, it’s pretty much the same as for meteors. Simulation the heat and pressure of liquid rock across the planet would be another burden on game devs, and on the player’s patience, But, volcanoes popping up sometimes - brilliant. Games generally have to cut corners for a lot of things, such as having the emergence of a volcano be isolated from anything else going on, rather than have multiple extra algorithms constantly running to determine the emergence and activity of volcanoes across the globe.

tl;dr: We can’t fully simulate everything. Continental drift, volcanoes, meteors, etc. will probably go into the game only as much as necessary.

[50gens]

It is also possible to simulate the geography beforehand and load the changed versions of the planet

[HexapodPhilosopher (Disguised as a rock, until you get too close...)]

Yes, that might be doable, if most areas of land stay the same shape while continents are moving.

[50gens]

Do you suggest generating planets by adding different continents from the thrivepedia?