Re: [therion] Re: [Therion] Feedback on 0.3.8 - queries

[John Pybus]

Stacho Mudrak wrote:
> There was no traffic in the mailing list, so I was worried, that all 
> the people that tried therion are disappointed with it.

Or perhaps we're all away surveying new caves, rather than drawing them
up ;-)

I've just got back from a month on expedition, and as soon I've caught
up with work will be scanning in some new scraps...

> Wookey wrote:
>
> > Colour scrap by altitude is nice but the abrubt joins can look
> > nasty in the middle of wide, nominally horizontal passage.  It
> > works really well in the 'soundriver' area where there are
> > nicely-merging shades of green, but nastily in other some other
> > areas. Some way to graduate the join a bit would make it look a lot
> > nicer. Or apply more detailed colour control to a scrap like
> > 'nearly the same as neighbour scrapname'.
>
>
> This I have to discuss with MartinB. As far as I know PDF - some
> gradient colorings are possible, but only for triangles. Not for
> bezier curves. So in principle, there are two possibilities:

I thought that the PDF spec provided considerable flexability in the
shadings, and it seems that it does.  From the Fourth edition of the PDF
reference, page 267 (avalable from:
http://partners.adobe.com/public/developer/en/pdf/PDFReference15_v5.pdf .)

------------
Various shading types are available, depending on the value of the
dictionary’s ShadingType entry:

• Function-based shadings (type 1) define the color of every point in
the domain using a mathematical function (not necessarily smooth or
continuous).
• Axial shadings (type 2) define a color blend along a line between two
points, optionally extended beyond the boundary points by continuing the
boundary colors.
• Radial shadings (type 3) define a blend between two circles,
optionally extended beyond the boundary circles by continuing the
boundary colors. This type of shading is commonly used to represent
three-dimensional spheres and cones.
• Free-form Gouraud-shaded triangle meshes (type 4) define a common
construct used by many three-dimensional applications to represent
complex colored and shaded shapes. Vertices are specified in free-form
geometry.
• Lattice-form Gouraud-shaded triangle meshes (type 5) are based on the
same geometrical construct as type 4, but with vertices specified as a
pseudorectangular lattice.
• Coons patch meshes (type 6) construct a shading from one or more color
patches, each bounded by four cubic Bézier curves.
• Tensor-product patch meshes (type 7) are similar to type 6, but with
additional control points in each patch, affording greater control over
color mapping.
------------

But a simple linear gradient across the join points of two scraps with
different colours would give a big improvement.

Cheers,

John

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