Right thanks, I think I'm a few (hundred) leagues below this, one day you'll
create a SPatch model and someone will create a nice little app that takes
the file and exports one simple image which you can paint on and UVMap
within Moray (though Moray doesn't currently support non-official stuff).
Until then I'll probably leave UVMapping - I have ago with UVMapper but it
confused the hell out of me!

Pete

Mike <Ama### [at] aolcom> wrote in message news:399CFE73.B484F167@aol.com...
> > Yes but you can have different uv mapping : planar, cylindrical,
> > spherical. Can I know more about it. Which procedure to follow
> > to get this texture?
>
> Well, by uv mapping I meant that the texture is mapped to the 2D space
> of the surface, which in the case of a bicubic patch is typically a unit
> square.
>
> The texture as much as it shows with the bad jpeg compression could
> pretty easily be achieved with a gradient y pigment.  But to get
> specific about what I did here, I wrote a patch for MegaPOV that does uv
> mapping for type 2 bicubic patches.  Then I changed the uv mapping code
> to calculate a 3x3 homogenous mapping matrix using the 4 corners of a
> quadrilateral (the uv vectors) assuming the patch space is a unit square
> and having the homogenous coordinate set to 1.  This matrix is used each
> time a ray intersects the surface of the patch by tranforming the u and
> v location of the patch at the current intersection to texture space (or
> maybe the other way around).
>
> Then I updated the pov-ray exporter for Animation Master available at
> http://free.prohosting.com/~olana/plugins/plugins.html to write the
> texture coordinates in pov format using the new syntax.  To keep things
> fast, I write a seperate include file with the textures needed for the
> model, otherwise each image would be parsed for each patch and it would
> take forever.  The new plugin hasn't been released yet though.  The
> problem is that I think I'm near the limit of my ftp space and can't
> upload everything there.
>
> It's plausible that this could be done by hand but I wouldn't want to.
> Some macros could probably be made to create the uv vectors, or in the
> case of sPatch models you could use a find and replace to add uv vectors
> that are a unit square, thus allowing for the mapping of a tilable
> image.
>
> I uploaded a copy of the windows binary with the new uv mapping and
> included a short text file explaining how the uv_vectors relate to the
> texture and the patch.  It's in povray.binaries.programming.  You should
> be able to render the scene files I uploaded to binaries.scene-files
> with it.
>
> As an example, here's what one patch looks like:
>
> bicubic_patch {
> type 2
> accuracy 0.1
> uv_vectors <0.5475359559059143, 0.9598205089569092>,
> <0.5189526081085205, 0.960773766040802>, <0.615035891532898,
> 0.7563253045082092>, <0.7078137397766113, 0.7766876816749573>
> <1.239059209823608, -0.01280438248068094, 1.6783527135849>,
> <1.065836906433106, 0.1083308532834053, 1.747843623161316>,
> <0.8545190691947937, 0.1975981742143631, 1.807306289672852>,
> <0.645129919052124, 0.2410857826471329, 1.846774458885193>,
> <2.281259059906006, 0.2899681329727173, 2.865853786468506>,
> <2.073765516281128, 0.5121513605117798, 2.92615818977356>,
> <1.813590884208679, 0.7627856731414795, 2.980928659439087>,
> <1.548043966293335, 0.8501358032226563, 3.049945831298828>,
> <3.277821063995361, 0.9094398617744446, 4.084438323974609>,
> <3.087475061416626, 1.274701952934265, 4.069855690002441>,
> <2.652498245239258, 1.616940975189209, 4.161567687988281>,
> <2.316552639007568, 1.618627786636353, 4.310638427734375>,
> <4.087599754333496, 1.740859031677246, 5.157229423522949>,
> <3.848036289215088, 2.162004947662354, 5.15593147277832>,
> <3.304417133331299, 2.48495364189148, 5.332837104797363>,
> <2.897367477416992, 2.485338926315308, 5.533927917480469>
> uv_mapping double_illuminate
> texture { Base0 }
> normal { Decal0 }
> interior { Interior0 }
> }
>
> (now that I look at that, I could probably save space by lowering the
> precision)
>
> and here's the textures I used.
>
> #declare Base0 =
>  texture {
>   pigment {
>      image_map {
>      tga "petalcolor.tga"
>      once
>      interpolate 4
>      }
>    scale <1, -1, 1>
>    translate 1*y
>    }
>      finish {
>      ambient 0
>      phong .9
>      phong_size 40
>      brilliance .5
>      diffuse .9
>      reflection 0
>      metallic
>     }
>   }
>
> #declare Interior0 =   interior { ior 1 }
>
> #declare Decal0 =
>    normal {
>      bump_map {
>      tga "petalbump.tga"
>      once
>      interpolate 4
>      }
>      bump_size 2
>    scale <1, -1, 1>
>    translate 1*y
>    }
>
> Probably way more than you wanted to know.  Sadly, this is something
> I've spent way too much time on and yet have a hard time explaining it
> to anyway.  None of the hash users want to be bothered with POV-Ray
> (they all want me to work on the RIB exporter tho none of them know jack
> about RIB. grrr).  Then when I mention Hash here it's like everyone
> thinks I've been smoking the stuff...still, I've been having a blast
> with all these low-tech tools I've cooked up. :-)
>

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