[x3d-public] Proposal: X3DFogObject startVisibility

[Holger Seelig]

All X3DFogObject nodes in X_ITE have a new field startVisibility.

X3DFogObject {
  SFFloat [in, out] visibilityStart 0 [0, infinity]
  ...
}

The motivation is to finely control fog more than it was possible before.

The startVisibility field defines the distance where the fog starts to fade the objects. The visibilityRange defines the range from zero fog to full fog. That means fog now start at startVisibility and ends at startVisibility + visibilityRange. Because startVisibility has a default value of 0 it will not break any existing X3D files.

An implementation of this behaviour should be trivial when shaders are used to render the scene.

The advantage of this new field is that the author can decide when fog fading starts and can have objects in the near environment not affected by the fog. It is also possible to create a fog wall, when visibilityRange very small.

There exist example files with use of startVisibility field to explore the exact behaviour. 

At first a very simple file where you can adjust startVisibility and visibilityRange and see what happens.

https://create3000.github.io/x_ite/playground/?url=https://create3000.github.io/media/examples/EnvironmentalEffects/Fog/Fog.x3d

Another file exists which shows an object near to the viewpoint, which is clear and sharp, but look at the horizon, the transition between the floor and the the clouds is very smooth because of the fog.

https://create3000.github.io/x_ite/playground/?url=https://create3000.github.io/media/examples/Navigation/Viewpoint/Viewpoint.x3d

Best regards,
Holger

—
Holger Seelig
holger.seelig at yahoo.de


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