 |
|
|
|
|
|
| |
| |
|
|
|
|
| |
| |
|
|
I've been playing around with mapping a texture onto half of an oblate spheroid,
and I've gotten really weird results.
Here's what I get:
The image seems to be half-scaled compared to the object it gets mapped onto.
The image has a weird "doubling" effect. (top right)
When I display the same hemi-spheroid as a guide, my image-mapped object
disappears, (lower right)
but when I rotate them at different angles, I can see the image map above, and
through the green below. (lower left)
Also interesting is the "chopping" going on between the 4 views.
It's like there's differencing going on between things that should be
independent.
.... I think the trouble may be due to the nut behind my keyboard ...
//#######################################################################
Image file:
http://news.povray.org/*/attachment/%3Cweb.54375641cbb3d8155e7df57c0%40news.povray.org%3E/medallion1.png
//#######################################################################
#version 3.7;
global_settings{ assumed_gamma 1.0 }
#include "debug.inc"
Set_Debug (true)
#include "colors.inc"
#include "textures.inc"
#include "glass.inc"
#include "metals.inc"
#include "golds.inc"
#include "stones.inc"
#include "woods.inc"
#include "shapes.inc"
#include "shapes2.inc"
#include "functions.inc"
#include "math.inc"
#include "transforms.inc"
#declare Feet = 12;
#ifdef (SDL)
// do nothing
#else
//--------------------------------------------------------------------------------------------------------<<<<
//--------------------------------------------------------------------------------------------------------<<<<
//------------------------------------------------------------- Camera_Position,
Camera_look_at, Camera_Angle
#declare Camera_Number = 0;
//--------------------------------------------------------------------------------------------------------<<<<
//--------------------------------------------------------------------------------------------------------<<<<
#switch ( Camera_Number )
#case (0)
#declare Camera_Position = < 0, 0, -4*Feet> ; // front view
#declare Camera_Look_At = < 0, 0, 0.00> ;
#declare Camera_Angle = 65 ;
#break
#case (1)
#declare Camera_Position = < 5.00, 5.00, -4.00> ; // diagonal view
#declare Camera_Look_At = < 0.70, 1, 0.00> ;
#declare Camera_Angle = 42 ;
#break
#case (2)
#declare Camera_Position = < 0.00, 1.00,-20.00> ; // front view
#declare Camera_Look_At = < 0.00, 1.00, 0.00> ;
#declare Camera_Angle = 65 ;
#break
#case (3)
#declare Camera_Position = < 0*Feet, 2*Feet, 0*Feet> ; // top view
#declare Camera_Look_At = < 0.00, 0*Feet, 0*Feet> ;
#declare Camera_Angle = 65 ;
#break
#case (4)
#declare Camera_Position = < 0.00, 9*Feet, 27*Feet> ; // mobile view
#declare Camera_Look_At = < 0.00, 0*Feet, 33*Feet> ;
#declare Camera_Angle = 65 ;
#break
#case (5)
#declare Camera_Position = < 0.00, 6*Feet, 35*Feet> ; // mobile view
#declare Camera_Look_At = < 0.00, 6*Feet, 25*Feet> ;
#declare Camera_Angle = 65 ;
#break
#else
#declare Camera_Position = < 0.00, 1.00,-20.00> ; // front view
#declare Camera_Look_At = < 0.00, 1.00, 0.00> ;
#declare Camera_Angle = 65 ;
#break
#end // of "#switch ( Camera_Number )" -----------------------------
//-------------------------------------------------------------------------------------------------------<<<<
//-------------------------------------------------------------------------------------------------------<<<<
camera { location Camera_Position
right x*image_width/image_height
angle Camera_Angle
look_at Camera_Look_At
}
light_source {<0*Feet, 0*Feet, -10*Feet> color rgb <1, 1, 1>*0.4}
// sky --------------------------------------------------------------------
sky_sphere{ pigment{ gradient <0,1,0>
color_map{ [0 color rgb <1, 1, 1> ]//White
[0.4 color rgb <0.14, 0.14, 0.56>]//~Navy
[0.6 color rgb <0.14, 0.14, 0.56>]//~Navy
[1.0 color rgb <1, 1, 1> ]//White
}
scale 2 }
} // end of sky_sphere
#end // end SDL check
#declare Medallion =
texture {
pigment {//uv_mapping
image_map {
png "Medallion1.png"
once
//map_type 1 // planar
//interpolate 0
//once
//texture { pigment {Red} }
//texture { Gold_Metal }
}
} //rotate x*90 //scale 0.25 translate <1, 0, 0>
}
#declare Gold = texture {T_Gold_2A finish {phong 1 metallic reflection {0.2}} }
#declare Sine = function (x,y) {sin (y/sqrt (pow (x,2) + pow (y,2)) )}
#declare Circle = function (x,y) { 1- (pow (x,2) + pow (y,2)) }
//##############################################################################
#declare Hemisphere =
union {
difference {
sphere {0, 1 }
box {0, 1 translate <-.5, -.5, 0> scale 2}
texture {Medallion translate -0.5}
scale <18, 18, 1.5>
}
cylinder {<0,0,0>, <10, 0, 0> 0.125}
cylinder {<0,0,0>, <0, 10, 0> 0.125}
cylinder {<0,0,0>, <0, 0, 10> 0.125}
}
#declare Hemispheroid =
difference {
sphere {0, 1}
box {0, 1 translate <-.5, -.5, 0> scale 2}
scale <18, 18, 1.5>
pigment {Green filter 0.99}
}
object {Hemisphere translate <-15, 10, 0> }
//object {Hemispheroid translate <-15, 10, 0>}
object {Hemisphere rotate x*70 translate <15, 10, 0> }
//object {Hemispheroid translate <15, 10, 0>}
object {Hemisphere translate <-15, -10, 0> }
object {Hemispheroid rotate x*70 translate <-15, -10, 0>}
object {Hemisphere translate <15, -10, 0> }
object {Hemispheroid translate <15, -10, 0>}
//##############################################################################
#declare Quarter =
height_field {
function 200,200 {
pattern {
function {Circle (x, y)}
// waves scale 0.1
// turbulence 0.8
}
}
translate -z*1
/*pigment{ gradient <0,1,0>
color_map{ [0 color rgb <0, 0, 0> ] //Blue
[1.0 color rgb <1, 1, 1> ] //White
}
}*/
scale <10, 5, 10> * 0.5
rotate x * 0
}
#declare MedallionFunction =
difference {
union {
object {Quarter}
object {Quarter rotate y*90}
object {Quarter rotate y*180}
object {Quarter rotate y*270}
}
sphere {0, 1 scale 2 inverse}
rotate x*90
texture {Medallion}
}
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
> I've been playing around with mapping a texture onto half of an oblate spheroid,
> and I've gotten really weird results.
>
> Here's what I get:
> The image seems to be half-scaled compared to the object it gets mapped onto.
> The image has a weird "doubling" effect. (top right)
> When I display the same hemi-spheroid as a guide, my image-mapped object
> disappears, (lower right)
> but when I rotate them at different angles, I can see the image map above, and
> through the green below. (lower left)
>
> Also interesting is the "chopping" going on between the 4 views.
> It's like there's differencing going on between things that should be
> independent.
>
> .... I think the trouble may be due to the nut behind my keyboard ...
>
> //#######################################################################
> Image file:
>
http://news.povray.org/*/attachment/%3Cweb.54375641cbb3d8155e7df57c0%40news.povray.org%3E/medallion1.png
> //#######################################################################
>
> #version 3.7;
> global_settings{ assumed_gamma 1.0 }
>
....
> #declare Feet = 12;
>
> #ifdef (SDL)
> // do nothing
> #else
>
//--------------------------------------------------------------------------------------------------------<<<<
>
//--------------------------------------------------------------------------------------------------------<<<<
> //------------------------------------------------------------- Camera_Position,
> Camera_look_at, Camera_Angle
> #declare Camera_Number = 0;
>
//--------------------------------------------------------------------------------------------------------<<<<
>
//--------------------------------------------------------------------------------------------------------<<<<
...
>
//-------------------------------------------------------------------------------------------------------<<<<
>
//-------------------------------------------------------------------------------------------------------<<<<
> camera { location Camera_Position
> right x*image_width/image_height
> angle Camera_Angle
> look_at Camera_Look_At
> }
...
>
> #declare Medallion =
> texture {
> pigment {//uv_mapping
> image_map {
> png "Medallion1.png"
> once
> //map_type 1 // planar
> //interpolate 0
> //once
> //texture { pigment {Red} }
> //texture { Gold_Metal }
> }
> } //rotate x*90 //scale 0.25 translate <1, 0, 0>
> }
The image is mapped from <0,0> to <1,1> (the X-Y plane) and extend along
the Z axis to infinity.
>
> #declare Gold = texture {T_Gold_2A finish {phong 1 metallic reflection {0.2}} }
>
> #declare Sine = function (x,y) {sin (y/sqrt (pow (x,2) + pow (y,2)) )}
> #declare Circle = function (x,y) { 1- (pow (x,2) + pow (y,2)) }
This should be:
#declare Circle = function (x,y) { 1- sqrt(pow (x,2) + pow (y,2)) }
>
>
> //##############################################################################
> #declare Hemisphere =
> union {
> difference {
> sphere {0, 1 }
> box {0, 1 translate <-.5, -.5, 0> scale 2}
> texture {Medallion translate -0.5}
> scale <18, 18, 1.5>
> }
This half sphere extend toward -Y and it's flat part is on the X-Z plane
The image is mapped relative to the X-Y plane.
You need to rotate the image_map +90*x, translate it by -0.5 along the X
axis and scale it by 2.
> cylinder {<0,0,0>, <10, 0, 0> 0.125}
> cylinder {<0,0,0>, <0, 10, 0> 0.125}
> cylinder {<0,0,0>, <0, 0, 10> 0.125}
> }
Reference axis, beter to colour them according to their directions: Red
for the X, Green for the Y and Blue for the Z are standard.
>
>
>
> #declare Hemispheroid =
> difference {
> sphere {0, 1}
> box {0, 1 translate <-.5, -.5, 0> scale 2}
> scale <18, 18, 1.5>
> pigment {Green filter 0.99}
> }
Coincident with the previous hemisphere. Make the sphere larger by a
*very* small amount: sphere{0, 1.00001}
Translate the box a tiny bit lower: box {0, 1 translate <-.5, -.50001,
0> scale 2}
Those changes will make sure that this object is realy visible.
>
> object {Hemisphere translate <-15, 10, 0> }
> //object {Hemispheroid translate <-15, 10, 0>}
>
> object {Hemisphere rotate x*70 translate <15, 10, 0> }
> //object {Hemispheroid translate <15, 10, 0>}
>
> object {Hemisphere translate <-15, -10, 0> }
> object {Hemispheroid rotate x*70 translate <-15, -10, 0>}
>
> object {Hemisphere translate <15, -10, 0> }
> object {Hemispheroid translate <15, -10, 0>}
>
>
> //##############################################################################
> #declare Quarter =
> height_field {
> function 200,200 {
> pattern {
> function {Circle (x, y)}
> // waves scale 0.1
> // turbulence 0.8
> }
> }
> translate -z*1
> /*pigment{ gradient <0,1,0>
> color_map{ [0 color rgb <0, 0, 0> ] //Black
> [1.0 color rgb <1, 1, 1> ] //White
> }
> }*/
> scale <10, 5, 10> * 0.5
> rotate x * 0
> }
>
> #declare MedallionFunction =
> difference {
> union {
> object {Quarter}
> object {Quarter rotate y*90}
> object {Quarter rotate y*180}
> object {Quarter rotate y*270}
> }
> sphere {0, 1 scale 2 inverse}
> rotate x*90
> texture {Medallion}
> }
>
>
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Alain <kua### [at] videotron ca> wrote:
> The image is mapped from <0,0> to <1,1> (the X-Y plane) and extend along
> the Z axis to infinity.
Yes, I understood that.
> This should be:
> #declare Circle = function (x,y) { 1- sqrt(pow (x,2) + pow (y,2)) }
True. I was messing around with all sorts of stuff, and abandoned that for the
time being while I tried to understand the mapping of a bona-fide hemisphere.
//##############################################################################
> > #declare Hemisphere =
> > union {
> > difference {
> > sphere {0, 1 }
> > box {0, 1 translate <-.5, -.5, 0> scale 2}
> > texture {Medallion translate -0.5}
> > scale <18, 18, 1.5>
> > }
>
> This half sphere extend toward -Y and it's flat part is on the X-Z plane
> The image is mapped relative to the X-Y plane.
> You need to rotate the image_map +90*x, translate it by -0.5 along the X
> axis and scale it by 2.
Nope.
First off, my sphere is centered at the origin with radius of 1.
Next, I make a box extending from the origin to <1,1,1>
Then it gets translated halfway to the left, and halfway down, so it's still
sticking back in the +z direction.
Then it gets scaled by 2, and since its front face is at z=0, it gets scaled
relative to the origin to give a box that extends from <-1, -1, 0> to <1, 1, 2>
This chops off the back side of the sphere to give the flat part in the X-Y
plane, and the front part of the sphere extends in the -z direction.
The image map is therefore shifted by -0.5 in each direction to center it on the
origin, since the z-translation is irrelevant.
You can actually see that this is the case in the image - the view is looking at
the origin from -z, the image is mapped onto the convex face of the hemisphere,
and the rotated green hemisphere shows that it started off with the flat in X-Y.
If it makes you feel any better, I somehow had x and z all twisted around in my
head the other day when rotating an image map texture.
I looked it over and fixed the scaling, and it looks a lot better. I got
confused between the image map itself, and the thing it was getting mapped on,
so I was expecting the "once" to map the image ONCE onto the _object_, but that
was my misinterpretation, and it did indeed need to be scaled.
> Coincident with the previous hemisphere.
I can't believe I got snookered by the coincident surface problem!
AAAAAAAAAAAAAaaaaaaaaaaaaaaaaaaaaaaaaaaaaarrrrrrrrrrrrrrrggggghhh!
:(
Thanks for helping me look this over - I took a walk, ate lunch, looked at it
with fresh eyes after you pointed those things out and it's looking like I
wanted and actually better than I expected.
Merci!
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
|
|
