 |
|
|
|
|
|
| |
| |
|
|
|
|
| |
| |
|
|
The code below generates five spheres which should be invisible, yet three
of them are visible from their interaction with the environment. The
spheres become visible when you apply a rotation to a texture that uses a
texture_map containing clear (rgbt <1,1,1,1>) components as in the
T_Electron texture below. If the texture is not rotated, then the sphere
remains invisible. Rotation applied to a clear texture not part of a
texture_map also remains invisible.
It also seems to be the case that the surface behind the spheres must have a
"normal" for the effect to occur. The effect goes away if you remove the
"normal" block in the texture of the "floor".
I realize the T_Electron texture as written below is pretty pointless, but
in the actual scene I am trying to create, not all of the texture map is
clear. The intent was to create a spherical shell of lightning with parts
of the texture_map representing the lightning, and the rest clear. The
problem I am having is the the clear portions affecting the appearance of
objects behind it. I removed the "lightning" portion for this example.
I am using povray 3.6
#include "colors.inc"
#declare T_Clear = texture {pigment { Clear }}
#declare T_Electron =
texture {
crackle
texture_map {
[0.00 T_Clear]
[1.00 T_Clear]
}
}
//
// Three of these spheres are visible (those at x positions -1,
// 0 and 1).
//
sphere { <-1,1,0>, 0.2 hollow texture { T_Electron rotate 90*y }}
sphere { <-0.5,1,0>, 0.2 hollow texture { T_Electron rotate 0*y }}
sphere { <0,1,0>, 0.2 hollow texture { T_Electron rotate 90*y }}
sphere { <0.5,1,0>, 0.2 hollow texture { T_Clear rotate 90*y }}
sphere { <1,1,0>, 0.2 hollow texture { T_Electron rotate 90*y }}
plane { y, 0
texture {
pigment {
checker
Red
White
scale 0.05
}
normal { bozo 4}
}
}
light_source {
<-8.0, 6, -10>
color rgb 2
}
camera {
//
// New Main view
//
look_at <0,1,0>
location <0,1.5,-2>
up <0,1,0>
}
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
gadoid nous apporta ses lumieres en ce 2007/09/06 16:11:
> The code below generates five spheres which should be invisible, yet three
> of them are visible from their interaction with the environment. The
> spheres become visible when you apply a rotation to a texture that uses a
> texture_map containing clear (rgbt <1,1,1,1>) components as in the
> T_Electron texture below. If the texture is not rotated, then the sphere
> remains invisible. Rotation applied to a clear texture not part of a
> texture_map also remains invisible.
>
> It also seems to be the case that the surface behind the spheres must have a
> "normal" for the effect to occur. The effect goes away if you remove the
> "normal" block in the texture of the "floor".
>
> I realize the T_Electron texture as written below is pretty pointless, but
> in the actual scene I am trying to create, not all of the texture map is
> clear. The intent was to create a spherical shell of lightning with parts
> of the texture_map representing the lightning, and the rest clear. The
> problem I am having is the the clear portions affecting the appearance of
> objects behind it. I removed the "lightning" portion for this example.
>
> I am using povray 3.6
>
> #include "colors.inc"
>
> #declare T_Clear = texture {pigment { Clear }}
>
> #declare T_Electron =
> texture {
> crackle
> texture_map {
> [0.00 T_Clear]
> [1.00 T_Clear]
> }
> }
>
> //
> // Three of these spheres are visible (those at x positions -1,
> // 0 and 1).
> //
> sphere { <-1,1,0>, 0.2 hollow texture { T_Electron rotate 90*y }}
> sphere { <-0.5,1,0>, 0.2 hollow texture { T_Electron rotate 0*y }}
> sphere { <0,1,0>, 0.2 hollow texture { T_Electron rotate 90*y }}
> sphere { <0.5,1,0>, 0.2 hollow texture { T_Clear rotate 90*y }}
> sphere { <1,1,0>, 0.2 hollow texture { T_Electron rotate 90*y }}
>
>
> plane { y, 0
> texture {
> pigment {
> checker
> Red
> White
> scale 0.05
> }
> normal { bozo 4}
> }
> }
>
> light_source {
> <-8.0, 6, -10>
> color rgb 2
> }
>
> camera {
> //
> // New Main view
> //
> look_at <0,1,0>
> location <0,1.5,-2>
>
> up <0,1,0>
> }
>
>
>
>
>
Strange. After playing with the rotation, it apears that the effect is affected
by the amount of the rotation, as well as the axis of the rotation. At rotation
90, 60 and 30 give me the most effect.
--
Alain
-------------------------------------------------
Coming soon: Windows for Nintendo!
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Alain <ele### [at] netscape net> wrote:
>
> Strange. After playing with the rotation, it apears that the effect is affected
> by the amount of the rotation, as well as the axis of the rotation. At rotation
> 90, 60 and 30 give me the most effect.
>
> --
> Alain
> -------------------------------------------------
> Coming soon: Windows for Nintendo!
It also seems to be the case that the effect remains even if you rotate the
object itself instead of the texture.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"gadoid" <hansen at tkgate.org> wrote in message
news:web.46e05e106d67f0f14e9a00c00@news.povray.org...
> The code below generates five spheres which should be invisible, yet three
> of them are visible from their interaction with the environment. The
> spheres become visible when you apply a rotation to a texture that uses a
> texture_map containing clear (rgbt <1,1,1,1>) components as in the
> T_Electron texture below. If the texture is not rotated, then the sphere
> remains invisible. Rotation applied to a clear texture not part of a
> texture_map also remains invisible.
>
> It also seems to be the case that the surface behind the spheres must have
> a
> "normal" for the effect to occur. The effect goes away if you remove the
> "normal" block in the texture of the "floor".
>
> ... snip ...
>
> #declare T_Clear = texture {pigment { Clear }}
>
> #declare T_Electron =
> texture {
> crackle
> texture_map {
> [0.00 T_Clear]
> [1.00 T_Clear]
> }
> }
>
> ... snip ...
> sphere { <0,1,0>, 0.2 hollow texture { T_Electron rotate 90*y }}
>
I'm taking a bit of a guess here, but maybe it relates to using a texture
that only contains a pigment for a crackle texture map. It looks a bit to me
like the sphere is acquiring a crackle normal. If you define T_Clear and
T_Electron as pigments and use a pigment_map the problem seems to go away.
If this is the cause though, I don't know why your texture would go clear at
a zero and 180 degree rotation around y.
Regards,
Chris B.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"Chris B" <c_b### [at] btconnectcomnospam> wrote:
> "gadoid" <hansen at tkgate.org> wrote in message
> news:web.46e05e106d67f0f14e9a00c00@news.povray.org...
> > The code below generates five spheres which should be invisible, yet three
> > of them are visible from their interaction with the environment. The
> > spheres become visible when you apply a rotation to a texture that uses a
> > texture_map containing clear (rgbt <1,1,1,1>) components as in the
> > T_Electron texture below. If the texture is not rotated, then the sphere
> > remains invisible. Rotation applied to a clear texture not part of a
> > texture_map also remains invisible.
> >
> > It also seems to be the case that the surface behind the spheres must have
> > a
> > "normal" for the effect to occur. The effect goes away if you remove the
> > "normal" block in the texture of the "floor".
> >
> > ... snip ...
> >
> > #declare T_Clear = texture {pigment { Clear }}
> >
> > #declare T_Electron =
> > texture {
> > crackle
> > texture_map {
> > [0.00 T_Clear]
> > [1.00 T_Clear]
> > }
> > }
> >
> > ... snip ...
> > sphere { <0,1,0>, 0.2 hollow texture { T_Electron rotate 90*y }}
> >
>
> I'm taking a bit of a guess here, but maybe it relates to using a texture
> that only contains a pigment for a crackle texture map. It looks a bit to me
> like the sphere is acquiring a crackle normal. If you define T_Clear and
> T_Electron as pigments and use a pigment_map the problem seems to go away.
> If this is the cause though, I don't know why your texture would go clear at
> a zero and 180 degree rotation around y.
>
> Regards,
> Chris B.
Hmmm. It seems to me to be more of a refraction-like effect, and changing
"crackle" to anything else does not change the way it renders. I've placed
an image at http://www.tkgate.org/povray/electrons.png (this is a test shot
for a larger scene) that has the problem in it. When you look through the
clear portion of the "electrons", you can see that the waves seem shifted
as though the sphere had an 'ior' in it. The "electrons" in this image are
made with an internal shiny metal sphere, and a co-located larger sphere
with the T_Electron texture to get the lightning cage effect. If I don't
rotate the "electrons", the clear portion behaves and does not cause a
problem.
This is the actual texture I am using:
#declare P_ElectricBlue = pigment { color rgb <0.178, 0.122, 1> };
#declare T_Lightning =
texture {
pigment { P_ElectricBlue }
finish {
ambient 5
brilliance 100.0
}
}
#declare T_Clear =
texture { pigment { Clear }}
#declare T_Electron =
texture {
// gradient y
crackle
turbulence .3
texture_map {
[0.000 T_Lightning ]
[0.0400 T_Lightning ]
[0.0800 T_Clear ]
[0.00 T_Clear ]
[1.00 T_Clear ]
}
scale 0.1
}
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"gadoid" <hansen at tkgate.org> wrote in message
news:web.46e07a2dc3c951274e9a00c00@news.povray.org...
>
> Hmmm. It seems to me to be more of a refraction-like effect, and changing
> "crackle" to anything else does not change the way it renders. I've
> placed
> an image at http://www.tkgate.org/povray/electrons.png (this is a test
> shot
> for a larger scene) that has the problem in it. When you look through
> the
> clear portion of the "electrons", you can see that the waves seem shifted
> as though the sphere had an 'ior' in it.
>
Well I've tried a whole load of things and I'm still not able to see exactly
what's causing it.
I don't think it's refraction because the background (e.g. the checkered
plane) is not distorted in any way.
I've done a small animation, rotating the sphere and it looks like clouds of
darkness and extra brightness are passing over the surface of the sphere as
it rotates, though the clouds don't seem to be rotating with the sphere.
When the sphere is above the checkered plane it starts as transparent at 0
degrees, becomes most perturbed at 90 degrees and becomes clear again at 180
degrees of rotation.
When the sphere is embedded halfway into a checkered plane the outer shell
goes transparent at 0 and 180 degrees still, but at 180 degrees the normals
from the part of the surface of the plane within the sphere appear reversed.
ie the ones that have only passed through the front surface of the sphere.
Indeed, if at 180 degrees the normal values are reversed each time the ray
passes through the surface of the sphere, it would explain why the rays
passing through both the front and back surfaces appear normal.
I'm not sure if any of this helps, but I thought I'd share my findings
before switching off for the night.
Regards,
Chris B.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"gadoid" <hansen at tkgate.org> wrote:
....
I may have narrowed the problem down for you. It appears to be affected
ultimately by the size of the normals of the plane behind the spheres.
Try removing the plane normal or making it smaller and see what happens. It
doesn't matter what normal type you have on the spheres, so it's not related
to the crackle pattern. Whatever is causing it, the normals on the plane
appear to be getting reversed by the spheres. For example try rendering
with "bozo 4" normal on the plane and then "bozo -4" and compare.
Hope this can help someone track down the reason or bug causing it.
-tgq
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
This is wierd. Somehow the normal of the
plane is being rotated by the clear spheres.
Must be some sort of bug. =(
The effect goes away if you remove the
normal from the plane.
Try this as a replacement...
#local cpig = pigment{checker Red*1.7 White*1.7 scale 0.05};
#local bpig = pigment{Black};
plane {y, 0 texture{pigment{bozo pigment_map{[0 cpig][1 bpig]}}}}
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"Trevor G Quayle" <Tin### [at] hotmailcom> wrote:
> "gadoid" <hansen at tkgate.org> wrote:
> ....
>
> I may have narrowed the problem down for you. It appears to be affected
> ultimately by the size of the normals of the plane behind the spheres.
>
> Try removing the plane normal or making it smaller and see what happens. It
> doesn't matter what normal type you have on the spheres, so it's not related
> to the crackle pattern. Whatever is causing it, the normals on the plane
> appear to be getting reversed by the spheres. For example try rendering
> with "bozo 4" normal on the plane and then "bozo -4" and compare.
>
> Hope this can help someone track down the reason or bug causing it.
>
> -tgq
I did notice the problem only happens when the surface beyond has a normal.
You are right that it may be reversing the normal, I at first thought it was
just shifting it. I'm beginning to think that this must be a POV-Ray bug,
but if it is, I need to find a work-around for my scene. I can't get rid
of the "normal" on the surface behind the object, because that is water and
I am using the normal to generate the waves. I have hundreds of the
"electron" objects in the scene. The only thing I can think of is to
#declare a different object for every orientation I need since the
unrotated objects seem to render fine.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
gadoid nous apporta ses lumieres en ce 2007/09/06 22:23:
> "Trevor G Quayle" <Tin### [at] hotmailcom> wrote:
>> "gadoid" <hansen at tkgate.org> wrote:
>> ....
>>
>> I may have narrowed the problem down for you. It appears to be affected
>> ultimately by the size of the normals of the plane behind the spheres.
>>
>> Try removing the plane normal or making it smaller and see what happens. It
>> doesn't matter what normal type you have on the spheres, so it's not related
>> to the crackle pattern. Whatever is causing it, the normals on the plane
>> appear to be getting reversed by the spheres. For example try rendering
>> with "bozo 4" normal on the plane and then "bozo -4" and compare.
>>
>> Hope this can help someone track down the reason or bug causing it.
>>
>> -tgq
>
> I did notice the problem only happens when the surface beyond has a normal.
> You are right that it may be reversing the normal, I at first thought it was
> just shifting it. I'm beginning to think that this must be a POV-Ray bug,
> but if it is, I need to find a work-around for my scene. I can't get rid
> of the "normal" on the surface behind the object, because that is water and
> I am using the normal to generate the waves. I have hundreds of the
> "electron" objects in the scene. The only thing I can think of is to
> #declare a different object for every orientation I need since the
> unrotated objects seem to render fine.
>
>
>
>
>
>
>
Don't rotate the texture! Instead, create the objects at the origin, rotate the
objects, thanslate them to the final position. As you are using spheres,
rotating the object or the texture will wave the same final aspect, minus the
normal alteration.
In my tests, the effect depends on the axis of rotation relative to the
camera-object vector. An object with a z rotation just in front of the default
camera show no effect, while the same object shifted up/down or lateraly will
exibit the effect.
--
Alain
-------------------------------------------------
When you don’t know what to do, walk fast and look worried.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
|
|
