Branching without if statement

Question

Is it possible to branch code without using an if statement?

Answer 1

Yes, you can, GPU-style.

Say you have a function that branches, and returns a value at the end.

float function( float input )
{
    if( input > 0 )
    {
        // do stuff
        finalValue = 2+4+8*input;
        return finalValue ;
    }
    else
    {
        // do other stuff
        finalValue = 1+input;
        return finalValue ;
    }
}

To do this without branching, you can write the code GPU-style: that is, evaluate both branches, then throw away the one you don't want at the end.

float function( float input )
{
    // do stuff..regardless
    finalValue1 = 2+4+8*input;

    // do other stuff..regardless
    finalValue2 = 1+input;

    bool resultMask = input > 0 ; // 1 if should use finalValue1.
    return finalValue1*resultMask   +   finalValue2*(1 - resultMask) ;
}

So there you have it. Branching without branching, if statements without if statementing.