Well I'll give it a go. There are four types of warping in Terragen.
1/ The "
Warp input shader" and "
Warp merge shader"
2/ The "
Fractal warp shader"
3/ The "
Vortex warp shader"
and separately
4/ The
Lead in warp effect>1 Octave Perlin warp on power fractal and cloud fractal warping tab.
Before I dive into an attempt at explaining these I will say the best way to find out answers to these (and any other TG question) is to set up a VERY simple scene. Create a power fractal (Perlin) with a very low octave (1 or 2) and a small overall scale so it's easy to see what is going on and apply the effect (try a Feature scale of 100, a lead in of 100, and a smallest scale of 10 to 50), and a displacement of 100. This will give you small rolling hills. Now you can apply the different warp effects and see what they do.1/ The "
Warp input shader" and "
Warp merge shader"
Your shader that you want "warping" goes into the "shader" input and the thing doing the warping goes into the warper input. You could use a power fractal or an image passed through a displacement node. The greater the displacement the greater the "warp". Imagine your power fractal as an image projected onto a rubber sheet, the "warper" can be viewed as something pushing through and distorting the sheet and the image on the sheet. "If" the power fractal or image you are using as a warper was instead simply being used as a displacement then the areas where the displacement is steepest (NOT GREATEST) is where the warping is larger. So in this image of a teddy bear the white areas and black areas and areas of constant value are not warped but where there is change in greyscale value, ie something that if it was a displacement would create steepness then these areas are warped. Long winded I know but I hope this makes sense.
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2/ The "
Fractal warp shader"
This applies a roughening of the displacement based on the slope of the area. The steeper the slope the more it is roughened. It's controls apply amount and size if the roughening. As always with terragen try some extreme values.
3/ The "
Vortex warp shader"
Simple one this time, twists what ever is plugged into it about the centre defined in its dialogue. be aware that if you use more that one the following vortexes will have their centre positions moved by the previous vortex shaders (unless you add a compute terrain, I need to test this).
and finally
4/ The
Lead in warp effect>1 Octave Perlin warp on power fractal and cloud fractal warping tab.
To be honest I really don't know what is going on here
Hopefully someone with a better understanding will jump in and correct my no doubt many mistakes but hopefully this will get you started.
Richard