how to get the color value?

Hi,

Refer to ViaAd Tutorial example P2_03, I have plot  some points on my
display.
The FunctionType I used is

(index ->(time, height, speed) )

func_i_tuple = new FunctionType( index, t_h_s_tuple);

index_set = new Integer1DSet(index, 200);

float[][]  point_vals = new float[3][200];

vals_ff = new FlatField (func_i_tuple,index_set);
vals_ff.setSamples(point_vals);

timeMap = new Scalarmap (time, Display.XAxis);
heightMap = new Scalarmap (height, Display.YAxis);
speedMap = new Scalarmap (speed, Display.RGB);

Click on the left mouse button, the value of time and height at mouse
click will display at upper left corner of the display window.
But I also like to know the speed value( i.e. color of point)  of the
point which is the most closest point to the mouse click point.
Since the speed is not the function of time and height, I don't think I
could use  Function.evaluate() to interpolates the function at the given
location as shown in tutorial.s6.P6_02 or P6_03.


Thanks in advance for pointing me a direction to turn.


helen