gain db control?

[debian]

How do I present to the user a gaincontrol from -94 db(completely silence) to +6 db(twice the volume)?

Can you help me how to think?
What I try to do was:

GetParam(kGain)->InitDouble("Gain", 0.0, -94.0, 6.0, 0.01, "db");
GetParam(kGain)->SetShape(2.0);

then in OnParamChange()
case kGain:
mGain = (GetParam(kGain)->Value()+94.0) / 100.;
mGain = mGain * 2.0;

But the result is not so good.. very little control between 0 and +6...

[Tale]

Well, this is how you normally would calculate from dB to linear:

GetParam(kGain)->InitDouble("Gain", 0.0, -94.0, 6.0, 0.01, "dB");

And then in OnParamChange():

    case kGain:
      mGain = pow(10, GetParam(kGain)->Value() / 20);
      break;

Or if you want -94.0 to map to exactly zero:

    case kGain:
    {
      const double value = GetParam(kGain)->Value();
      mGain = value > -94.0 ? pow(10, value / 20) : 0;
      break;
    }

However, this will still have much more control between -94 and 0 than between 0 and 6, but mabe you can tweak this to liking using SetShape().

[debian]

Excellent!
Thanks a lot Tale!
with SetShape(0.095) it turned out perfect :-)