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General => Terragen Discussion => Topic started by: nikita on August 08, 2007, 09:35:42 AM

Title: Displacement before compute terrain?
Post by: nikita on August 08, 2007, 09:35:42 AM
I've been told, any significant displacement should be done before compute terrain. Alright, makes sense.
But now I made a file for which this seems impossible.
A screenshot of the network, the file itself and two images are attached to this post.

When I swap compute terrain and the power fractal (unlike shown in the screenshot), the displacement of the fractal almost isn't visible.
I tried varoius tricks to solve this:
- Adding a Tex Coords shader before: no effect
- Adding a Compute Normal or an additional Compute Terrain before: The terrain becomes totally messed up
- Trying to use a displacement shader instead: no effect
- several combinations of the above
Title: Re: Displacement before compute terrain?
Post by: Volker Harun on August 08, 2007, 09:49:23 AM
When using a Compute normal, try to increase its patch size, then increase it again.
Title: Re: Displacement before compute terrain?
Post by: nikita on August 08, 2007, 10:03:08 AM
It has no effect.
Title: Re: Displacement before compute terrain?
Post by: Volker Harun on August 08, 2007, 10:11:40 AM
Increase it again ... it has an effect!
A hint: which year do we have?
Title: Re: Displacement before compute terrain?
Post by: nikita on August 08, 2007, 10:37:48 AM
I want to place the fractal before the compute terrain - the patch size doesn't have an effect then.
Title: Re: Displacement before compute terrain?
Post by: Volker Harun on August 08, 2007, 10:41:07 AM
Redirect --- Compute normal --- Fractal --- Compute terrain
Title: Re: Displacement before compute terrain?
Post by: Volker Harun on August 08, 2007, 10:43:44 AM
But it is only necessary if you want to populate on those displacements. Else, imho, you do not need it.
Title: Re: Displacement before compute terrain?
Post by: nikita on August 08, 2007, 10:53:44 AM
Oh.. you meant compute normal... I should read more carfully, sorry. :-\

Ok, so this works. :)
But I can't reproduce the result this way. And why are such large values necessary? All this doesn't really make sense to me.
Title: Re: Displacement before compute terrain?
Post by: Volker Harun on August 08, 2007, 10:57:40 AM
Neither to me ... small patch sizes never worked for me ... try larger values, that might give back your terrains original appearance.
As long as you do not want to populate, forget it, as any additional Compute-node sucks time.
Title: Re: Displacement before compute terrain?
Post by: FrankB on August 08, 2007, 11:59:37 AM
Quote from: Volker Harun on August 08, 2007, 10:57:40 AM
Neither to me ... small patch sizes never worked for me ... try larger values, that might give back your terrains original appearance.

Funny - I wasn't aware of that either.
Title: Re: Displacement before compute terrain?
Post by: Tangled-Universe on August 08, 2007, 12:23:21 PM
What does this "gradient patch size" do then?

Martin
Title: Re: Displacement before compute terrain?
Post by: nikita on August 08, 2007, 12:33:46 PM
it's a measure for how accurate the terrain is being calculated. It doesn't calculate the normal for each inch/centimeter of a terrain but for relatively large chunks/patches. You can specify the scale of these with "gradient patch size".
Title: Re: Displacement before compute terrain?
Post by: Tangled-Universe on August 08, 2007, 04:07:06 PM
Ah well, that's very clear, thank you!

Martin