Author Topic: Alpine fractal shader v2  (Read 3578 times)

Offline AP

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Re: Alpine fractal shader v2
« Reply #15 on: December 15, 2015, 08:04:00 AM »
No problem. There is no information on the Wiki about this so maybe someone from Planetside can weigh in.

Offline AP

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Re: Alpine fractal shader v2
« Reply #16 on: December 15, 2015, 08:57:04 AM »
The goal is still the same but struggling with proper scales and patterns. The picture gives a better indication. Red marks long wide valleys, green are those hanging valleys that a hard to get and blue being the glaciers is a might not happen.

Offline AP

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Re: Alpine fractal shader v2
« Reply #17 on: December 16, 2015, 11:46:51 PM »
Can anyone weigh in on the scaling issue from Planetside? I'm still trying to figure it out. Thank you.

Offline Matt

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Re: Alpine fractal shader v2
« Reply #18 on: December 17, 2015, 12:27:59 AM »
The lead-in octaves for the Alpine shader, how does one know how large the main features are and does it multiply the Feature scale itself for every octave added?

When "Lead-in octaves" = 0, the largest cells occur at the scale of "Feature scale".
Additional lead-in octaves add cells that are larger than "Feature scale". How much larger depends on "Scale step" on the Settings tab (although this setting also controls the scale ratio of smaller octaves as well as largers ones).

For example, if "Feature scale" = 4000 and "Scale step" = 3:

Lead-in octaves 0 => largest cells are 4000 metres across.
Lead-in octaves 1 => largest cells are 12000 metres across.
Lead-in octaves 2 => largest cells are 36000 metres across.
... etc.

Lead-in octave cells have the same displacement amplitude as the cells that occur at the "Feature scale", and they also contribute to the flow of smaller cells in a different kind of way. So when considering how steep the mountains are, where you want to think about the relationship between amplitude and scale, it is better to think about the relationship between "Displacement amplitude" and "Feature scale", but not the scale of lead-in octaves, and that's why I chose to parameterise it this way.

Matt
Just because milk is white doesn't mean that clouds are made of milk.

Offline AP

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Re: Alpine fractal shader v2
« Reply #19 on: December 17, 2015, 04:17:44 AM »
Thank you for the in-depth reply. It gives me a much better idea of what the scale perimeters do. By the way you describe the largest cells, visually what i had seen did give me a fair idea of the sizes i needed but a good explanation of that so it certainly helped a lot. The eye tends to pick up easily what looks fake and what looks real so understanding scales can be important even on a localized level. However, i'm getting closer now.    :)
« Last Edit: December 17, 2015, 09:32:45 AM by Chris »