Pray tell, how does noise-based heightmapping work? Imagine that you assign a random value to a set square of textures. This is basic noise, but it does not produce a pretty sight:
If we zoom in the actual values (that is to say, set the positions[z][x] = noise[z/8][x/8]) we can get a little averaged control, right?
If you like New York.
There's also the idea of smoothed out terrain, which actively takes noise and bilinearly interpolates it for each position (give or take a bit of change from the fractional portion of a float value). Vary this by positions divided by a set size and you get something slightly more interesting (size: 64):
Still looks like a bed of spikes, so we'll need to smooth it out further. Based on the concept of turbulence, or adding noise in at different octaves, we now have a function to specify a size and work its way down a series of octaves, adding their smoothed noise. It's a bit more costly, but produces some impressive looks:
Which one to choose, though? They each have different things to change; the fractal side has randomness reduction and amount of subdivisions, but its points are limited by the amount of subdivisions. As for noise, there is no limit on a square's side, and the amount of octaves can deepen the detail.
I did a test with chrono's duration casting and tested the amount of ticks required for each function. In this case, the fractal generation takes half as much time to load as the Perlin turbulence noise (!!!)
What to choose? For the final product, diamond-square takes the cake. What's next? Texturing time!
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