Re: [RFC] Gradient fill options

[<HBB...@t-...>]

Pierre wrote:
> On 2/2/07, Hans-Bernhard Bröker <HBB...@t-...> wrote:
>> To give an example, from an RGB palette defined like this:
>>
>> 0.0: blue
>> 0.5: white
>> 1.0: red

> I'm not sure to understand the notion of palette in your example.

It's a (principally) continuous mapping from a numeric value (the number 
being displayed) to a colour.  In the case above, it consists of two 
linear paths, one from blue to white, the second from white to red.  The 
idea is to turn a data parameter into a colour, a.k.a. "false-colour 
diagram".  It's how altitude is often displayed on geographical maps 
(green lowlands, brown hills, white peaks, blue ocean).

> Which and how many colors do you have in the palette when you start to
> render a given triangle?

As many as the output terminal can supply --- potentially infinite. 
This "palette" is a data visualization thing, not the like-named 
property of paletted image file formats like GIF.  You may want to call 
our thing a "color map" or even a "false-color map" to distinguish the two.