It thickens a surface with triangular mesh.

## Parameters

`points`

: A list of`[x, y, z]`

s.`thickness`

: The depth of the thickening.`triangles`

: Determine which points are connected by an edge. All triangles have points in the same direction, counter-clockwise. If it's ignored,`sf_thickenT`

would use`[x, y]`

to do Delaunay trianglation.`direction`

: The direction of thickening. It accepts`"BOTH"`

(default),`"FORWARD"`

or`"BACKWARD"`

. Thickening is applied in both directions from the surface, the direction of the surface normals or the opposite direction to the surface normals. It also accept a direction vector`[x, y, z]`

. Thickening is only applied in the direction you give.

## Examples

```
use <surface/sf_thickenT.scad>;
thickness = .2;
a_step = 15;
r_step = 0.2;
function f(x, y) = (y ^ 2 - x ^ 2) / 4;
points = [
for(a = [a_step:a_step:360], r = [r_step:r_step:2])
let(
x = r * cos(a),
y = r * sin(a)
)
[x, y, f(x, y)]
];
sf_thickenT(points, thickness);
```

```
use <triangle/tri_delaunay.scad>;
use <surface/sf_thickenT.scad>;
u_step = 10;
v_step = 0.2;
thickness = .2;
points = [
for(u = [0:u_step:360], v = [-1:v_step:1])
let(
x = (1 + v / 2 * cos(u / 2)) * cos(u),
y = (1 + v / 2 * cos(u / 2)) * sin(u),
z = v / 2 * sin(u / 2)
)
[x, y, z]
];
triangles = tri_delaunay([
for(u = [0:u_step:360])
for(v = [-1:v_step:1])
[v, u]
]);
sf_thickenT(points, thickness, triangles);
```