Confused

[yossam]

I've got a scene that I'm working on that has me really confused as hell.


I have a heightfield generate that is masked by a simple shape (0,0,0). I add a lake also centered at origin with a height of 10. The lake does not show in the preview. If I disable the terrain the lake magically appears. I have to raise the lake height to about 160 before it appears in the preview window. According to the coordinate info in the preview window the height at the center of the simple shape is 0.


Could someone please explain to my greatly confused brain what is going on.

[Kadri]

Yossam just looked a little but i think it is only a altitude problem in your "Lake 01" water node.
Put the numbers of the highfield altitude in the "Lake 01" node and it works.
174 or whatever you prefer for example.

[yossam]

What I don't understand is why I have to put it so high just to get it to show up. The center of the simple shape is at 0 height, or so the preview window says. That is what is confusing me. 

[Kadri]

Yossam what i understand is this:
The shape shader comes always where the real 0,0,0 position is on the Planet .
It isn't important if there is any displacement or not.
When you use displacement your planets altitude changes but the shape shader is still on the undisplaced 0,0,0 coordinates like before.
Not sure if this makes sense but it looks confusing yes.

Your shape shader is under the ground basically now.So you have to use the displaced terrain altitude.

[Dune]

You could see the simple shape as a column, or a projection down. No matter if it's at 1000m or -1000, it will still influence it's described area.

[yossam]

So the water shader will work with a fractal terrain masked by a simple shape, but not a heightfield generate?

[Dune]

The lake you mean? There's no difference, a generated terrain is just a small part of the planet, workings of masks are the same.

[yossam]

Maybe I'm not making myself clear...........................when you open the default scene there is a simple shape masking the terrain (fractal). You can add a lake and it is visible in the scene at a height of 1.


In my scene it is the same setup, except the terrain is a heightfield generate. When you add a lake in my scene, you have to raise the height to roughly 170 before it ever appears. Why? 

[kaedorg]

Your heighfield generate is altering the area around the real 0,0,0 position.

It gives a relief and also changes the altitude of the ground around this position.
Altitude now is around 174 meters as you can see it while moving the mouse in the preview window (y coordinate).

If you add a lake, the original altitude of 1m will make its surface behind the ground around the real 0.0.0 position.
If you want it to appear over the ground at this position, you just need to raise its altitude.

[Kadri]

All of the above and think of the Lake object as kinda another planet with a water shader on it Yossam.
If you don't raise the altitude of the lake node you can not see the water because the heighfield node does have raised the altitude before it.