Plot a piecewise function of two variables [closed]

How can I plot with Mathematica, Muller's example:

$f(t,x) = \begin{cases} 0 & t \leq 0, x \in \mathbb{R} \\ 2t & t>0,x < 0 \\ 2t - \frac{4x}{t} & t >0,0 \leq x \leq t^2 \\ -2t & t>0,x > t^2 \, . \end{cases}$

which is a piecewise function of two variables?

Other examples

Plot a parametric function from $\mathbb{R}^2$ to $\mathbb{R}^2$

closed as off-topic by m_goldberg, zhk, Coolwater, José Antonio Díaz Navas, MarcoBMar 27 '18 at 23:29

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question arises due to a simple mistake such as a trivial syntax error, incorrect capitalization, spelling mistake, or other typographical error and is unlikely to help any future visitors, or else it is easily found in the documentation." – m_goldberg, zhk, Coolwater, José Antonio Díaz Navas, MarcoB
If this question can be reworded to fit the rules in the help center, please edit the question.

• Have you read about Piecewisein the documentation?... – José Antonio Díaz Navas Mar 25 '18 at 11:25
• Try f[x_, t_] := Piecewise[{{0, t <= 0}, {2 t, t > 0 && x < 0}, {2 t - 4 x/t, t > 0 && 0 <= x <= t^2}, {-2 t, t > 0 && x > t^2}}] and Plot3D... – José Antonio Díaz Navas Mar 25 '18 at 11:35

f[t_, x_] = Piecewise[{{0, t <= 0}, {2*t, t > 0 && x < 0}, {2*t - 4*x/t,
t > 0 && 0 <= x <= t^2}, {-2*t, t > 0 && x > t^2}}]

Plot3D[f[t, x], {t, -4, 4}, {x, -4, 4}, Exclusions -> None]