🚀 go-pugleaf

sjm@miles.com (Scott Mark) writes:

>I have been thinking about doing animations with POV, but it seems that
>the texture I'm using (DMFWood4) shifts when I move my camera!

From the documentation:

#       When animating objects with solid textures, the textures
#       must move with the object, i.e. apply the same rotate or
#       translate functions to the texture as to the object itself.
#       This is now done automatically if the transformations are
#       placed _after_ the texture block. Example:
#
#       object {
#         shape { ... }
#         texture { ... }
#         scale < 1 2 3 >
#       }
#
#       Will scale the shape and texture by the same amount.
#
#       object {
#         shape { ... }
#         scale < 1 2 3 >
#         texture { ... }
#       }
#
#       Will scale the shape, but not the texture.

Other things to keep in mind when creating several images for an
animation: (again, from the documentation)

#       Textures and Animation
#       If you are doing animation, you should specify all object
#       transformations after the texture transformations so the
#       texture "follows" or "sticks to" the object through 3-D
#       space. For example,
#
#       object {
#          shape {}   // Shape description
#          texture {} // Texture description
#          scale     // transform after shape & texture
#          rotate    // transform after shape & texture
#          translate // transform after shape & texture
#       }
#
#       As in:
#
#       object{
#          box {<-1 -1 -1> <1 1 1>} // Box shape centered on zero
#          texture {
#             agate
#             phong 1
#             scale <1.3 2 1.3> // scale texture to the
#                               // untransformed shape
#             rotate <30 0 0>   // rotate texture to the
#                               // untransformed shape
#          }
#          scale <3 3 3> // scale *both* sphere & texture
#          rotate <0 40 0> // rotate *both* sphere & texture
#          translate <1 5 5> // Move box & texture to final
#                            // position
#       }
#
#       If the transformations are done after the shape and before
#       the texture, the texture will not "stick to" the shape. In
#       an animation, this will look like the texture is constantly
#       moving on the moving shape. What is actually happening is
#       that the shape is moving and the texture is not, so the
#       texture on the shape changes whenever the shape is scaled,
#       rotated, or translated. This can be an interesting effect,
#       but is not desirable for most animations.

and

#         Random Dither
#       The floating-point value given immediately following the
#       texture keyword is an optional "texture randomness" value,
#       which causes a minor random scattering of calculated color
#       values and produces a sort of "dithered" appearance. This is
#       used by artists to minimize banding and to provide a more
#       chaotic, uneven look to a texture. Values are generally kept
#       quite small, like .05. This feature is different from
#       turbulence in that textures using it will look slightly
#       different each time they are rendered.
#
#       NOTE: This should not be used when rendering animations.
#       This is the only truly random feature in POV-Ray, and will
#       produce an annoying flicker of flying pixels on any textures
#       animated with a "randomness" value used.

and

#       WARNING: Image files created on with different executables
#       on the same or different computers may not look exactly the
#       same due to different random number generators used in some
#       textures. If you need to merge image files from different
#       computers contact the authors for more info.

Hope that helps.

-- 
                                                    John "Dudley" Hunkins
                                                  dudley@matt.ksu.ksu.edu

In article <1ispmoINNbh7@matt.ksu.ksu.edu> dudley@matt.ksu.ksu.edu (D U D L E Y) writes:
>sjm@miles.com (Scott Mark) writes:
>
>>I have been thinking about doing animations with POV, but it seems that
>>the texture I'm using (DMFWood4) shifts when I move my camera!
>
>From the documentation:
>
>#       When animating objects with solid textures, the textures
>#       must move with the object, i.e. apply the same rotate or
>#       translate functions to the texture as to the object itself.
>#       This is now done automatically if the transformations are
>#       placed _after_ the texture block. Example:

From the original posting:   (No offense intended, but read what I _wrote_!)

>I have been thinking about doing animations with POV, but it seems that
>the texture I'm using (DMFWood4) shifts when I move my camera!
                                                        ------


I am not moving objects, before or after applying textures.  For completeness
I am including the scene file below.  It is short.  It doesn't take long
to render with antialiasing turned off.

When I render the following scene, I get some nice variation to the rings
running diagonally from top-front-left of the box to bottom-front-right.

If I move the camera to <1 7 -10> to get a closer look, the variation
disappears!  Just nice smooth concentric rings.

I was under the impression that the textures were deterministic, unless
there was the optional floating point value right after the keyword.

-------------------------- cut here ---------------------------

#include "colors.inc"
#include "shapes.inc"
#include "textures.inc"

camera {
/*
	location	<1 7 -10>
*/
	location	<1 15 -10>
	direction	<0 0 1.5>
	up		<0 1 0>
	right		<1.33 0 0>
	look_at		< 0 4 -4>
}

object {
	light_source {
		<1 15 -10>
		color White
	}
}

object {
/*
	intersection {
		box { <-4 4 0> <4 10 5> translate <0 0 -4> }
		plane { <0 0 1> 0 rotate <0 45 0> }
		plane { <0 0 1> 0 rotate <0 -45 0> }
	} bounded_by {
		box { <-4 4 0> <4 10 5> translate <0 0 -4> }
*/
	box { < -4 -4 -4> < 4 4 4> 
	} texture {
		DMFWood4
	} color White
} 

/* one board's texture, fairly nice
		DMFWood4
		rotate < 94 0 0>
		translate <0 0 -4>
		rotate < 0 5 0>
		scale <4 1 1>
*/

-------------------------- cut here ---------------------------

Scott Mark
sjm@miles.com

sjm@miles.com (Scott Mark) writes:

>From the original posting:   (No offense intended, but read what I _wrote_!)

>>I have been thinking about doing animations with POV, but it seems that
>>the texture I'm using (DMFWood4) shifts when I move my camera!
>                                                        ------

>I am not moving objects, before or after applying textures.  For completeness
>I am including the scene file below.  It is short.  It doesn't take long
>to render with antialiasing turned off.

>When I render the following scene, I get some nice variation to the rings
>running diagonally from top-front-left of the box to bottom-front-right.

>If I move the camera to <1 7 -10> to get a closer look, the variation
>disappears!  Just nice smooth concentric rings.

[ data file deleted ]

Not trying to make you feel like a bonehead or anything :) but .... there
is nothing wrong with your texture. You have the same texture in both
viewpoints. The reason they look different is due to the Moire effect. The
pixel resolution of your monitor is unable to accurately respresent the
pixel rez of the data file.

I traced both views with the following options:
  +w320 +h200 -v +d +ft +b300 +a0.1 +q9
and converted both images to rle format. They are available for ftp from
matt.ksu.ksu.edu (in incoming) for a short time. You will need to have
getx11 installed to view them. I recommend using the zoom feature (mouse
buttons) of getx11.

With the zoom functions it is plainly obvious that both of the wood grains
consist of nearly straight lines.

-- 
                                                    John "Dudley" Hunkins
                                                  dudley@matt.ksu.ksu.edu