[osg-users] [Fwd: Re: to draw landscapes beginning from a matrix]

[Vincent Bourdier]

Hi Aurora,

With his proposition, you can create the color that you need.
Setcolor(vec4) uses RGBA (Red, Green, Blue, Alpha) color (if i remember
well) so put A to 1.0 (opacity) , and the RGB can be defined using the
function he gives to you... you can use it for each component if you want a
greyscale color (R=G=B) or only use it on one component... try it and you
will see...

for greyscale image, you can try :

hightcolor = 1.0
lowcolor = 0.0

and then

R =(highColor - lowColor) * ((altitude - minAltitude) / maxAltitude) +
lowColor;
G =(highColor - lowColor) * ((altitude - minAltitude) / maxAltitude) +
lowColor;
B =(highColor - lowColor) * ((altitude - minAltitude) / maxAltitude) +
lowColor;

this is just a simple example...

Regards,

Vincent.

2008/2/29, aurora restivo <aurora_re at tiscali.it>:
>
>  The Sukender ha scritto:
>
> Hum... I don't have a global solution, but you may set a color for each vertex with something lile :
> color = (highColor - lowColor) * ((altitude - minAltitude) / maxAltitude) + lowColor;
>
>
>
>
> I apologize but I am still inexperienced.
>
> I have a HeightField associated to shapeDrawable (this because if I use
> Locator and GeometryTechnique I succeed in visualizing the alone ground
> "GEOCENTRIC"),
> therefore if I use
>
> shapeDrawable - > setColor (Vec4);
>
> I don't know whether to plan the values of the Vec4 with the formula that
> you have sent me
>
> besides of what type it is color?
>
> Aurora
>
>
>
>  You can allso do it in HSL coordinates (instead of RGB).
>
> Sukender
>
> ----------------------------------------
>
>  Date: Fri, 29 Feb 2008 12:54:48 +0100
> From: aurora_re at tiscali.it
> To: osg-users at lists.openscenegraph.org
> Subject: Re: [osg-users] [Fwd: Re: to draw landscapes beginning from a	matrix]
>
> Hi!
>
> does a way exists to color from the tallest altitude of a ground to the
> lowest with gradations of color?
>
> thanks
> Aurora
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