Calculates the 2nd moment of surface area about the origin by multiplying the surface area of
each triangle in the mesh by its distance from the origin (should be set to
the attachment point of the mesh). The sum of these values is the 2nd moment
of area.#' This metric is size-dependent so to compare moments in terms of shape only, set scale = TRUE.

`sma(mesh, axis = "z", scale = FALSE, origin = TRUE)`

## Arguments

- mesh
A triangular mesh of class mesh3d.

- axis
The axis along which to calculate the second moment of area. z is the default.

- scale
Logical. Scale the object to have a volume = 1? Default = FALSE

- origin
Logical. Set the origin to the bottom left corner of bounding box? Default = TRUE.

## Examples

```
sma(mcap)
#> [1] 0.03294466
sma(mcap, scale = TRUE)
#> [1] 3.732545
```