private void colorFunc2(GL gl, float x, float y, float z) {
        float[] rgba;

        float q = 0.20f;

        float blueBegin   = 0.00f;
        float blueEnd     = 0.35f;
        //\\//\\//\\//\\//\\//\\//
        float greenBegin  = 0.35f;
        float greenEnd    = 0.60f;
        //\\//\\//\\//\\//\\//\\//
        float brownBegin  = 0.60f;
        float brownEnd    = 0.85f;
        //\\//\\//\\//\\//\\//\\//
        float whiteBegin  = 0.85f;
        float whiteEnd    = 1.00f;

        if (inRange(y, blueBegin, blueEnd-q)) {
            rgba = blue;
        }
        else if (inRange(y, blueEnd-q, blueEnd)) {
            rgba = scale4f(
                sum4f(
                    scale4f(blue,  (blueEnd   - y)),
                    scale4f(green, (blueEnd-q + y))
                ),
                1.00f
            );
        }
        else if (inRange(y, greenBegin, greenEnd-q)) {
            rgba = green;
        }
        else if (inRange(y, greenEnd-q, greenEnd)) {
            rgba = scale4f(
                sum4f(
                    scale4f(green, (greenEnd   - y)),
                    scale4f(brown, (greenEnd-q + y))
                ),
                1.00f
            );
        }
        else if (inRange(y, brownBegin, brownEnd-q)) {
            rgba = brown;
        }
        else if (inRange(y, brownEnd-q, brownEnd)) {
            rgba = scale4f(
                sum4f(
                    scale4f(brown, (brownEnd   - y)),
                    scale4f(white, (brownEnd-q + y))
                ),
                1.00f
            );
        }
        else if (inRange(y, whiteBegin, whiteEnd)) {
            rgba = white;
        }
        else {
            //throw new RuntimeException("Unexpected value: " + y);
            //System.err.println("Unexpected value: " + y);
            rgba = purple;
        }

        //color(gl, new float[] {1f, 1f, 1f, 1f});
        color(gl, rgba);
    }