# Variable parameter range in parametric_plot3d?

Is it possible to give parametric_plot3d parameter ranges where one parameter is a function of the other? For example, I would like the following command to execute and create a plot of a triangle in $\mathbb{R}^3$.

```
v = some vector
w = some other vector
someTriangle = parametric_plot3d(t*v + s*w, (t,0,1-s), (s,0,1))
```

Thanks!