Multiple compute terrains

[FlynnAD]

On prior posts, it's stated that generally you want to make your terrain, then apply any displacements to it, then run it into a compute terrain node, then add color and objects.

1) Since objects and populations normally want to sit on the terrain, do people usually have a second compute terrain node placed just before their populations if they have, at any point, added some displacement along with their surface color? It seems that it would be pretty hard to ALWAYS create all of your displacement before creating any color, as sometimes your displacement and color are the same power fractal node. But if you displace your terrain along with color after you've computed your terrain, don't you need to compute the terrain again? Otherwise your populations have the chance of floating in air or being buried.

2) Do people typically have more than one compute terrain? If so, what are some typical situations when you need more than one compute terrain?

Thanks

[TheBadger]

Hi

This quote is from a resent thread it should begin to answer your questions:

The basic rule of thumb for shaders that create displacement is, when the shader will create large displacements, it should go before the Compute Terrain (so that textures and object distribution after it will be placed correctly, based on the computed terrain results), whereas smaller displacements would go after the Compute Terrain in the Shaders area, especially in cases where a shader (like a Power Fractal) potentially provides both color *and* displacement.

- Oshyan

There are lots of threads about this subject. The problem is that users often give threads names that don't match the real subjects of the posts, making searching hard. Also, a lot of times posts end up with multiple subjects as a conversation evolves. I'm sure someone will answer your questions directly here though. And thanks for giving your post a name that makes sense.

Sorry Flynn I realize your an experienced user, I just think we should all start witting in this section of the forum in a more, whats the word, sterilized way, perhaps? Because of what I mention above. Your post name makes sense, so I moved that quote here because your topic will now come up first in a search with your keywords.

[Tangled-Universe]

On prior posts, it's stated that generally you want to make your terrain, then apply any displacements to it, then run it into a compute terrain node, then add color and objects.

1) Since objects and populations normally want to sit on the terrain, do people usually have a second compute terrain node placed just before their populations if they have, at any point, added some displacement along with their surface color? It seems that it would be pretty hard to ALWAYS create all of your displacement before creating any color, as sometimes your displacement and color are the same power fractal node. But if you displace your terrain along with color after you've computed your terrain, don't you need to compute the terrain again? Otherwise your populations have the chance of floating in air or being buried.

2) Do people typically have more than one compute terrain? If so, what are some typical situations when you need more than one compute terrain?

Thanks

1) This is complicated matter, yet the solution is often pretty simple: don't use a second compute terrain and set the very last shader of your network as the "sit on shader" shader.
Does the population not match up? Then you can consider adding an extra compute terrain.

Be aware that you can compute your terrain separately for your population and that you won't have to feed it into the planet shader. This may save you extra calculation time for your rendering of the image as the 2nd compute terrain's result will only be used for positioning your population. See?

2) Above is a reason why you can use 2 compute terrains.
Other reasons can be that you're using very vertical/stretched terrains as a base and calculate these with high precision (is low patch size in compute terrain). After that step you can add additional lateral displacement (some displacement types require a compute terrain/normal to function properly, so here's another reason) and compute that terrain again in order to texture if after that.
There are probably more reasons, but these came quickly to me.

[jo]

Hi Matt,

This documentation might be helpful to you:

http://www.planetside.co.uk/wiki/index.php/Compute_Terrain

Regards,

Jo

[elipsis1]

Now that was some good documentation 

I love to learn things like that.  Thanks!

[Hetzen]

I'm not sure where to find the link to the wiki page, I have it book marked. It might be a good idea to have it as a sticky at the top of this sub forum.

And I have noticed that nodes are getting fuller descriptions over time.

[Oshyan]

The wiki is linked from the main site under Resources. We may consider adding a link here, but I'd prefer to eventually just integrate the main site header and nav (a minimized version at least) into the forum theme so there's always common nav to move between areas. I think the main site gets forgotten by a lot of people once they're in the forums, but there are a lot of resources linked from it, and it expands progressively too.

- Oshyan