VPython绘图半球

Question

I have a sphere plotted on my program as so:

ball=sphere(pos=vector(0,0,0),opacity = 0.5,radius=0.95,color=color.black)

Is there any way of making it only show the top half of the sphere?

I'm using vpython.

Thank you,

Answer 1

The best way to do this is make an extrusion. Make your shape a quarter of a circle, then arc the extrusion in a whole 60 degrees. If you see the extrusion examples they have a lot of help about this and so does the documentary of vpython.

ex:

    circle = shapes.circle(radius=20) #you can use the size of your choice
    square1 = Polygon[(-10,-20),(-10,20),(0,20),(0,-20)]
    square2 = Polygon[(0,0),(0,20),(20,20),(20,0)]

    rotation = paths.arc(radius=20, angle2=pi)

    Hemisphere = extrusion(pos=rotation,shape=circle-square1-square2)

not sure if this is fully syntax error free, etc. but I think you understand the idea behind this. The quarter of a circle get rotated from the centre until it make a complete hemisphere. Hope you get the idea, just did this but for making a full sphere with a chuck taken out as if a slice of cake was out of the sphere.

Answer 2

您可以制作一个黑色的盒子，使其覆盖一半的球面，但除此之外，我不知道对不起

Answer 3

just to be clear i have done this using extrusions, only i needed a 3/4 of a sphere. Make a half cirlce shape by calling circle then subtract a square on half the circle. After this make your rotation equal to 1pi (half a circle) here is how to do it:

    S1 = shapes.circle(radius=1)

    angle = 180 #degrees
    angle = angle=angle*(pi/180) #convert to radians (1pi)

    sq = Polygon([(-10,-20),(-10,20),(0,20),(0,-20)])
    semicircle = paths.arc(radius=0.000000001, angle1=pi/2, angle2=2.2*pi)

    mf = frame()
    Layer20_Extrusion = extrusion(frame=mf,pos=semicircle, shape=S1-sq,color=wh)

    mf.rotate(angle=angle)
    mf.pos=(0,0,0)

you will have to rotate it so that its the top half missing instead of the side,

haven't used this code in a while so i am not sure why the radius = 0.0000000001 ish but i think you should be able to figure out what i did, sorry for the late response with code, when you posted this question i was trying to solve the same issue.