Here are two mel commands to calculate the area of a face in world space:

```
global proc float areaOfTriangle( string $mesh, string $vertIndices[] ) {
vector $verts[3];
// get the transform node for the mesh
string $transform[] = `listRelatives -p $mesh`;
// query the matrix transform
float $transformMatrix[] = `xform -q -ws -m $transform[0]`;
int $i;
for ($i=0; $i<3; $i++) {
// vert pos with tweaks
vector $vert = `getAttr ($mesh+".vt["+ $vertIndices[$i] +"]")`;
vector $offset = `getAttr ($mesh+".pt["+ $vertIndices[$i] +"]")`;
$vert = $vert + $offset;
// apply the transform matrix to the point
float $v[] = pointMatrixMult($vert, $transformMatrix);
$verts[$i] = <<$v[0], $v[1], $v[2]>>;
}
// calculate the area using the cross product of vectors
vector $v1 = $verts[1] - $verts[0];
vector $v2 = $verts[2] - $verts[0];
return abs(cross($v1, $v2)) / 2;
}
global proc float areaOfPolygon( string $mesh, int $face ) {
float $area = 0;
// get the vertex indices
select -r ($mesh+".f["+$face+"]");
string $vertIndicesStr[] = `polyInfo -fv`;
// place the indices into an array
string $vertIndices[];
tokenize $vertIndicesStr[0] $vertIndices;
// note the vert count for the polygon
int $vertCount = `size($vertIndices)` - 2;
// calculate the area based on polygon type
// triangle
if ($vertCount == 3) {
string $triangle[3] = {$vertIndices[2], $vertIndices[3], $vertIndices[4]};
$area = areaOfTriangle($mesh, $triangle);
}
// quad (decompose into two triangles)
else if ($vertCount == 4) {
//
string $triangle1[3] = {$vertIndices[2], $vertIndices[3], $vertIndices[4]};
string $triangle2[3] = {$vertIndices[2], $vertIndices[4], $vertIndices[5]};
$area = areaOfTriangle($mesh, $triangle1) + areaOfTriangle($mesh, $triangle2);
}
// n-gon (decompose into n - 2 triangles where n = # of verts)
else {
int $i;
for ($i=0; $i < $vertCount-2; $i++) {
string $triangle[3] = {$vertIndices[2], $vertIndices[$i+3], $vertIndices[$i+4]};
$area += areaOfTriangle($mesh, $triangle);
}
}
return $area;
}
```

You call the main function like this with the mesh shape and the face number you want the area for:

```
$area = areaOfPolygon("pSphereShape1", 25);
print ($area + "
");
```

You could get the total area of a selected mesh like this (works up to a couple thousand faces, then it is prohibitively slow):

```
float $area = 0;
// get selection
string $sel[] = `ls -sl`;
if (size($sel) == 0)
error "No objects were selected.
";
string $s[] = `listRelatives -s $sel[0]`;
int $f[] = `polyEvaluate -f $s[0]`;
string $mesh = $s[0];
int $faceCount = $f[0];
int $i;
for ($i=0; $i<$faceCount; $i++)
$area += areaOfPolygon($mesh, $i);
print("Total area: " + $area + "
");
```

There may be a much faster way to do this in mel. The slowdown is maybe polyInfo- it has to run on a selected face. On a couple thousand polygons, that’s a lot of selections! Yet, for testing a couple faces, the command is instantaneous.

-shawn