introduced Interval in random.ts (#91)

This adds a new `Random.inInterval()` method and uses it.

lib/random-colors.ts

@@ -27,14 +27,15 @@ function createRandomColor(rng: Random): string {
   //See if we can pull out a sample inside the LUV solid
   for (let i = 0; i < max_luv_samples; i++) {
     //bounds from https://docs.opencv.org/2.4/modules/imgproc/doc/miscellaneous_transformations.html#cvtcolor
-    let L = rng.inRange({ min: 0, max: 100, step: 0.1 });
-    let u = rng.inRange({ min: -134, max: 220, step: 0.1 });
-    let v = rng.inRange({ min: -140, max: 122, step: 0.1 });
+    let L = rng.inInterval({ min: 0, max: 100 });
+    let u = rng.inInterval({ min: -134, max: 220 });
+    let v = rng.inInterval({ min: -140, max: 122 });
     let rand_color = colorspaces.make_color("CIELUV", [L, u, v]);
 
     //console.log(`L:${L},u${u},v${v}`);
     if (rand_color.is_displayable() && !(L == 0.0 && (u != 0 || v != 0))) {
       rand_color_hex = rand_color.as("hex");
+      //console.log(rand_color_hex);
       luv_sample_failed = false;
       break;
     }

lib/random.ts

@@ -1,4 +1,4 @@
-import { inclusiveRange, NumericRange } from "./util";
+import { inclusiveRange, NumericInterval, NumericRange } from "./util";
 
 export type RandomParameters = {
   modulus: number;
@@ -58,6 +58,13 @@ export class Random {
     return this.choice(inclusiveRange(range));
   }
 
+  /**
+   * Return a number in the interval, second argument is really supremum which return value is always less than
+   */
+  inInterval({ min, max }: NumericInterval): number {
+    return this.next() * (max - min) + min;
+  }
+
   /**
    * Return a random item from the given array. If the array is
    * empty, an exception is thrown.

lib/util.ts

@@ -28,9 +28,12 @@ export function rad2deg(radians: number): number {
   return (radians * 180) / Math.PI;
 }
 
-export type NumericRange = {
+export type NumericInterval = {
   min: number;
   max: number;
+};
+
+export type NumericRange = NumericInterval & {
   step: number;
 };