Lines Matching refs:fog

23     Patchy fog is a fog in which intermittent areas of dense fog may
24     be encoutered. This extension explains how the patchy fog
25     extension is supported. Patchy fog is needed because both 
26     uniform fog density and fog layers can only specify a constant
28     extension gives a mean to specify a patchy fog texture that will 
29     modulate the fog density at a given elevation. The goal of this
30     document is to describe the modulation fuction and the fog
31     equation when patchy fog is enabled. No tokens, states, or 
43     - Should we introduce a glEnable for patchy fog?
45     - We should move the description of the patchy fog equation
61     In addition to uniform fog density and fog layers, patchy fog can
62     be specified. The patchy fog extension gives a mean to modulate
63     the fog density with a texture.
67                                  |  *  |____|  *  |__ To fog equation
73     patchy fog texture (p)  __|          |
79     The product (d*p*r) is used in the computation of the fog blending
80     factor (f). If the patchy fog texture is not enabled in SGIX_fog_texture, 
81     then the patchy fog texture has no effect (p = 1.0).
83     The computation of the fog equation when patchy fog is enabled
85     approach. If there are more than one patchy fog layer or more
86     than one patchy fog color, the second pass will be repeated
90     fragment using the fog blending equation. In this first pass,
91     the fog patchiness is ignored (p=1).
97       - f1 is the fog blending factor. It is a function of the fog
102       - [RGBfog] is the fog color.
105     result of the previous pass. In the second pass, the fog
106     patchiness is taken into account (p=patchy fog texture)
112       - f2 is the fog blending factor. It is a function of the fog
114 	space (r), and the patchy fog texture (p). In the hardware, the density
115 	is first multiplied by the patchy fog texture and then
118 	without patchy fog.
119       - [RGBcloud] is the patchy fog color.