How to remove unnessecary parts in an plot (Maple)

Question

A few minutes ago; I made an answer to this question. As can be seen, the desired volume is really surrounded by $x=0,~y=0,~z=0,~x+y=1,~x^2+z=1$. My question is how can I make the plot in which I remove the unnecessary parts from the output. Indeed, on $xy-$plane, we don't need the triangle part with $(1,0),(1,1),(0,1)$. Thanks for your time and thanks for your help.

Answer 1

plot3d(1-x^2, x=0..1-y, y=0..1, filled=true, style=surface);