[Squeakland] sketch's color

[Bert Freudenberg]

Am 23.06.2005 um 04:40 schrieb Randy Heiland:

> Thanks Andreas,
>
> Honestly, I'm not sure.  For starters, the world/fixSketches script
> is a bit of magic I don't understand, not to mention that it's
> apparently a text-only script.  However, I don't think this addresses
> one of my wishes - which is to be able to set the color of a sketch's
> stamp (multiple stamps, multiple colors, assigned by an RGB vector).

The stamp in Andreas' example has the right color, doesn't it?

So what you need is setting the color from RGB. There is a nice  
apparatus for visualizing the RGB color model: the color cube. You  
can even buy on at

     http://www.colorcube.com/puzzle/puzzle.htm

It's made by arranging tiny cubes in a three-dimensional grid  
according to their colors. Black is at the origin (0,0,0), white at  
the opposite corner (1,1,1).

This cube can be simulated with an etoy project, and thus positions  
converted into colors. Here's how:

1) Make images of the color cube sliced into layers. Just drop the  
attached images into a holder:

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2) Make an object "cube" showing the current slice (as in an holder  
animation)
2) Get an Ellipse, and give it three variables named "r", "g", and  
"b", place it on top of the cube
3) Make a ticking script that maps r, g, and b:
- the slice is selected according to r (set holder's cursor to r, and  
cube's graphic to holder's graphic-at-cursor)
- the ellipse is moved according to g and b ("g" moves on the x- 
direction, "b" in y)
4) set "Ellipse's color" to "Ellipse's colorUnder"
5) now changing r, g, and b in the (0...5) interval sets the ellipses  
color.

Here is a project to demonstrate this:

               http://www.squeakland.org/project.jsp?http://impara.de/ 
~bert/RGBColors.002.pr

And here's an older version using a slightly different approach to  
convert 3D-2D:

           http://www.squeakland.org/project.jsp?http://impara.de/ 
~bert/RGBColors.001.pr

A much less etoys-like approach is this: make a tile that directly  
converts RGB numbers into a color:

1) make a variable "col", set its type to Color
2) make variables "r", "g", "b"
3) drag out the arrow to assign to "col", this makes a new script
4) switch to text mode
5) use this to assign the color from r, g, and b:

script1
     self
         setCol: (Color
                 r: self getR
                 g: self getG
                 b: self getB)

6) set r to 1, g to 1, b to 0, run the script, col will be yellow.


> Another wish is to be able to dynamically set the color of a pen
> trail, again via RGB.

Andreas' hack could eventually be used to recolor pen trails (that  
is, all of them at once).

- Bert -