Re-mapping a value (Java)

From: Randy (never_at_home.com.invalid)
Date: 11/27/03 

Date: Thu, 27 Nov 2003 09:13:39 GMT

I am working with some simple 3-D stuff, and have just re-written some
Visual BASIC code for Java. My re-mapping routine no longer works!, so
I am curious as to what is the best procedure for re-mapping a value
from one scale to another. In this case, the first scale is the z-value
of a coordinate within my 3-D model, typically between -5000 and 0
(-5000 to zero) [Since it's VB code, those are probably twips, not
pixels]. The second scale is 0-255 (zero to 255), for determining the
palette adjustment. I want the function to return an integer between
0-255. I am passing the minimum and maximum z values, and two points
(it works for lines, but for points, I just pass the same value twice).

Here is the method/function. I know that it is weak code:

// (Graphics object 'g' passed for debugging in applet)
static int get_RemappedRGBValue(Graphics g,
                                 int minZ,
                                 int maxZ,
                                 int p1,
                                 int p2) }

     int delta_p1_p2; // distance between the two points (z-axis)
     int range; // total possible range (for z-value)
     int remapped; // z-value, remapped to RGB scale (0-255)
     long halfwayPoint; // halfway-point (used for lines only)

   range = maxZ - minZ; // get full range for z-value

    // get distance between two points, and the halfway point
     if (p1 < p2) {
       delta_p1_p2 = p2 - p1;
       halfwayPoint = p1 + (int)(delta_p1_p2 / 2);
     }
     else { // (if [p1 > p2])
       delta_p1_p2 = p1 - p2;
       halfwayPoint = p2 + (int)(delta_p1_p2 / 2);
     }

  // calculate the new value
   remapped = (int)(((halfwayPoint - minZ) / range) * 255);

  // adjust 'brightness'
   remapped = remapped - 24;

    // fix out-of-bounds errors, if any occur
     if (remapped < 0)
         remapped = 0;

     if (remapped > 255)
         remapped = 255;

   return remapped;

} // {get_RemappedRGBValue}

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