Adding a constant value to each die roll

In Gamma World there are certain effects that add bonus damage to each damage dice.  eg plus +3 per damage dice would do +3 on 1d6 or 1d8, but +9 on a 3d6 roll.

Obviously I could just have the player enter the total damage bonus, for each weapon.  This gets a little confusing for them, IME, but not unpossible to do.

Alternatively, I could separate the number of dice from the die type in the character sheet, then build the roll piece by piece. 
eg @{numOfDice}d@{dieType} + ((@{numOfDice}*@{perDieDmgBonus} )  + @{stdDmgBonus})

Ideally though, I'd rather do something like 

3d(6+@{perDieDmgBonus} ) + @{stdDmgBonus}

Obviously that does not work (it rolls a d9 instead), but hopefully you get the gist.

If you're using a single Attribute to handle number and type of dice rolled, you can do something like this to account for the per-die bonus:

[[ @{damageDice} + [[@{damageDice}>0 * 3]] + @{stdDmgBonus} ]]

That looks great.  Can you explain to me how it works?  I assume the '>0' is the magic bit?  Going to try it now.

Also, would this be a legit construction.
[[ @{damageDice} + [[@{damageDice}>0 * @{perDieDmgBonus}]] + @{stdDmgBonus} ]]

The >0 is how many of the dice rolled greater than 0. So as all of them will this is the number of dice in the roll. So 3d6>0 will be 3 which you can then * the per die bonus. It is using the success format to extract the number of dice essentially.

[[ @{damageDice} + [[@{damageDice}>0 * @{perDieDmgBonus}]] + @{stdDmgBonus} ]]
should work as long as everything is linked up right.

For historic reasons, > is actually "Greater than or equal to" in dice context.