         calcSamplePos().y > 1)
         colorTF = borderColor_;
 
-    // increase alpha to allow better visibility by 1 - (1 - a)^4 and then add "noBackground_" to
+    // increase alpha to allow better visibility by 1 - (1 - a)^4 and then add "backgroundAlpha_" to
     // set alpha to 1 if no background is wanted
     colorTF.a = min(1.0f - pow(1.0f - colorTF.a, 4.0f) + backgroundAlpha_, 1.0f);
 

    vec2 alteredPosition = mirrorVertically(position_);

    vec2 pixelPosA = alteredPosition * alteredDimensions - (alteredLegendSize / 2.0);
    // apply possible horizontal mirroring of output image
    pixelPosA += alteredLegendSize * mirrorHorizontal;
    vec2 screenPosA = pixelPosA / alteredDimensions;

    vec2 pixelPosB = alteredPosition * alteredDimensions + (alteredLegendSize / 2.0);
    // apply possible horizontal mirroring of output image
    pixelPosB -= alteredLegendSize * mirrorHorizontal;
    vec2 screenPosB = pixelPosB / alteredDimensions;

    // map the fragment coordinates to the legends local coordinates


// map the gl_FragCoord to the transfer function coordinates
vec2 calcSamplePos() {
    // mirror variables vertically
    vec2 alteredDimensions = mirrorVertically(dimensions_);
    vec2 alteredFragCoords = mirrorVertically(gl_FragCoord.xy);
