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# Thread: Help condensing nested if blocks

1. ## Help condensing nested if blocks

I am writing a particle physics engine, and I have a fairly verbose section of code to calculate relative masses when there are massless particles involved. It seems like it should be reducible down to some concise math and fewer if statements. Can you suggest any ways to do this? I'd appreciate the help.

m -> a mass
w -> an inverse mass (1/m) used by the physics engine

when w = 0, the particle has infinite mass and does not move
when w > 0, the particle has some normal amount of mass, unless...

unless m = 0, in which case the particle has no mass
so w values for the other particles must be adjusted to compensate

Here's the relevant code:
Code:
```// calculate relative node weights
var w0:Number = n0.w;		// node 0 weight
var w1:Number = n1.w;		// node 1 weight
var w2:Number = n2.w;		// node 2 weight

// check whether nodes are weightless
if ( n0.m )
{
if ( n1.m )
{
if ( n2.m )
{
// keep weights as they are
}
else
{
// only node 2 should move
w0 = w1 = 0;
w2 = 1;
}
}
else
{
if ( n2.m )
{
// only node 1 should move
w0 = w2 = 0;
w1 = 1;
}
else
{
// node 1 and node 2 should move
w0 = 0;
w1 = w2 = 1;
}
}
}
else
{
if ( n1.m )
{
if ( n2.m )
{
// only node 0 should move
w1 = w2 = 0;
w0 = 1;
}
else
{
// node 0 and node 2 should move
w1 = 0;
w0 = w2 = 1;
}
}
else
{
if ( n2.m )
{
// node 0 and node 1 should move
w2 = 0;
w0 = w1 = 1;
}
else
{
// all nodes are equal
w0 = w1 = w2 = 1;
}
}
}```

2. Any suggestions? I'm using AS2, Flash Player 8. Thanks.

3. Code:
```// calculate relative node weights
var w0:Number = n0.w;
// node 0 weight
var w1:Number = n1.w;
// node 1 weight
var w2:Number = n2.w;
// node 2 weight
// check whether nodes are weightless
w0 = (n0.m) ? 0 : 1;
w1 = (n1.m) ? 0 : 1;
w2 = (n2.m) ? 0 : 1;```

4. Hmm, I'm afraid it's more complicated than that... I appreciate the reply though.

Basically if (n0.m == 0) then I want to set (n1.w = n2.w = 0) and (n0.w = 1). Is that possible to do in a simpler way than above?

5. Well, those conditional statements that dawsonk suggested can be calls to functions instead of values. The functions can set the variables to what you want.
Code:
`w0 = (n0.m) ? setWeights1() : setWeights2() ;`
so make the functions set the values. Obviously the variables need to be global. You can set up those conditional statements to suit your needs. I didn't spend much time looking at this solution and I'm not sure by your last reponse if the conditionals should be w0= or n0.m == 0. if the latter

Code:
`n0.m == 0 ? setWeights1() : setWeights2() ;`
So maybe you can figure if conditional statements can work for you. If not, maybe else if statements might be better

Code:
```if ( n0.m && n1.m && n2.m ){
// keep weights as they are
}
else if ( n0.m && n1.m && !n2.m ){
// only node 2 should move
w0 = w1 = 0;
w2 = 1;
}

else if ( n0.m && !n1.m && n2.m ){
// only node 1 should move
w0 = w2 = 0;
w1 = 1;
}

else if ( n0.m && !n1.m && !n2.m ){
// node 1 and node 2 should move
w0 = 0;
w1 = w2 = 1;
}

else if ( !n0.m && n1.m && n2.m ){
// only node 0 should move
w1 = w2 = 0;
w0 = 1;
}

else if ( !n0.m && n1.m && !n2.m ){
// node 0 and node 2 should move
w1 = 0;
w0 = w2 = 1;
}

else if ( !n0.m && !n1.m && n2.m ){
// node 0 and node 1 should move
w2 = 0;
w0 = w1 = 1;
}

else if ( !n0.m && !n1.m && !n2.m ){
// all nodes are equal
w0 = w1 = w2 = 1;
}```
Hope this helps

6. Thank you, that helps. I will compare my options.

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