|
 |
> Hi,
>
> I am using the Fog feature to add depthcuing to a scene in povray 3.6 and the
> new 3.7. For this puropse I rotate the ground fog 90 degrees so that it is
> getting denser in the back and it works quite well.
>
> However, I noticed that when I have a transparent object close to the observer
> looking at some depthcued/foggy objects behind it, the fog is essentially
> removed from it. This looks odd and breaks the depthueing. This refers to the
> linux (CentOS 6.5) version of povray - did not try windows.
>
> The following shows a set of red cubes with depthcuing. The right side has a
> transparent triangle in front and the cubes in the back behind the triangle
> appear to have the fog removed.
>
> This is either a bug or an incorrect use of some povray feature by me. If there
> is an alternative to do depthcuing please let me know.
>
> //Start
> global_settings {
> ambient_light rgb <0.40000, 0.40000, 0.40000>
> assumed_gamma 1.800
If you use version 3.7, you should use 1, 2.2 OR srgb for your
assumed_gamma. Other values will be altered to 1 or 2.2.
> adc_bailout 0.00390
> max_trace_level 5
> }
>
> #declare camera_direction = < 0.0, 0.0, -1.0 >;
> #declare camera_location = < 0.0, 0.3, 3.0 >;
> #declare camera_angle = 10;
> #declare camera_look_at = < 0.0, 0.0, -1.0 >;
>
> camera {
> location camera_location
> right x * 1.00000
> direction camera_direction
> angle camera_angle
> look_at camera_look_at
> }
>
>
> background { color rgb < 1.0000, 1.0000, 1.0000 > }
>
> light_source {
> <0.0, 0, 100>
> color rgb 1
> }
> light_source {
> <0.0, 500, 0.1>
> color rgb 1
> }
>
> #declare Usefog = 1;
> #ifdef (Usefog)
> #declare DEPTH_RGB = <1.000, 1.000, 1.000>;
> fog {
> distance 0.2424 * 8
> fog_alt 0.01
> fog_offset -1.1437 + 1
> fog_type 2
> rotate x*90
> color rgb DEPTH_RGB
> }
> #end
>
>
> #declare b = box {
> <-0.1,-0.1,-0.1>, <0.1,0.1,0.1>
> }
>
> #declare idz = 0;
>
> #while (idz < 9 )
>
> object {
> b
> texture {
> pigment { color rgb <1,0,0> }
> finish { ambient 0.8 diffuse 0.3 specular 0.1 roughness 0.05 }
> }
> translate <-0.12,0.0, -idz*0.5>
> }
> object {
> b
> texture {
> pigment { color rgb <1,0,0> }
> finish { ambient 0.8 diffuse 0.3 }
> }
> translate <0.12, 0.0, -idz*0.5>
> }
>
> #declare idz = idz+1;
> #end
>
>
> #declare TrigTrans = 0.8;
>
> triangle {
>
> <-1,-0.5,0>, <0.0,0.5,0.0>, <1,-0.5,0>
> translate <1.4, 0.8,0>
> scale 0.11
> rotate z*45
> texture { pigment { color rgbt <0.8, 0.8, 0.8, TrigTrans> }
> finish {ambient 0.4 diffuse 0.3 specular 0.2 roughness 0.01} }
> }
>
>
>
>
>
The problem is that you use a single surfaced object: A triangle.
When the ray encounter it, what is behind is concidered as been "inside"
a non-hollow object.
When the ray encounter a surface, the fog stops been evaluated. When the
ray encounter a second surface, the fog evaluation resumes.
Also, if the ray reatch the background, the fog is NOT evaluated.
The workaround can be:
- Use an union of two parallel triangles.
- Use a thin triangle shaped prism object.
For either, you need to increase the transparance to compensate for the
two surfaces.
Alain
Post a reply to this message
|
|
