mathematica 画图的不连续性问题

Manipulate[

Plot[Evaluate@

Piecewise[{{0,x < 0}, {x^2/2, 0 <= x < 1}, {-x^2 + 3 x - 3/2,

1 <= x <2}, {1/2 (3 - x)^2 + i, 2 <= x < 3}, {0,

x >=3}}], {x, -1, 4}], {i, 0, 0.05}]