Shader: "ground fog"

"ground fog"

Class Foreground

Synopsis Simulates a layer of fog whose density decreases with altitude.

Arguments

"fog distance"	Type:	LtFloat
	Default:	1000.0
	Range:	[ 0, inf ]
	Hint:	[ 0, inf ]
"fog height"	Type:	LtFloat
	Default:	0.0
	Range:	[ -inf, inf ]
	Hint:	[ -inf, inf ]
"fog colour"	Type:	LtColour
	Default:	(1.0, 1.0, 1.0)
	Range:	[ 0, inf ], [ 0, inf ], [ 0, inf ]
	Hint:	[ 0, 1 ], [ 0, 1 ], [ 0, 1 ]
"ground point"	Type:	LtPoint
	Default:	(0.0, 0.0, 0.0)
	Range:	[ -inf, inf ], [ -inf, inf ], [ -inf, inf ]
	Hint:	-
"ground normal"	Type:	LtVector
	Default:	(0.0, 0.0, 1.0)
	Range:	[ -inf, inf ], [ -inf, inf ], [ -inf, inf ]
	Hint:	[ -1, 1 ], [ -1, 1 ], [ -1, 1 ]
"max density"	Type:	LtFloat
	Default:	1.0
	Range:	[ 0, 1 ]
	Hint:	-
"ignore background"	Type:	LtBoolean
	Default:	TRUE
	Range:	-
	Hint:	-

Location lishclas

Description

This shader is used to create more subtle fog like effects than the standard "fog" shader. With this shader the fog density decreases exponentially along a user specified axis. The parameter "fog height" sets the rate of decrease (if this is set to zero or a negative value, the effect is the same as with the standard "fog" shader).

The parameters "ground point" and "ground normal" define the place where the fog lies. It is assumed to be the plane z=0 by default.

Note that fog does not exist at all below the ground plane, so in the default case there is only fog in the z>0 halfspace.

The density of the fog is clamped to a maximum value specified by parameter "max density". By default this value is 1.0. Values between 0.0 and 1.0 are sensible - values less than zero will be interpreted as zero and values greater than one will be interpreted as one.

The fog effect can be enabled or disabled for background pixels using "ignore background". By default this is set to TRUE, i.e., there is no fog effect applied to background pixels.

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