[Visualpython-users] Buttons and sliders

[Bruce S. <ba...@an...>]

Attached is a zip file of which the following is the final, test portion. 
To run the complete program you need the latest version of VPython (which 
implements full mouse control).

The test routine is shown below. Establish a normal VPython graphics window 
with a red cube in it. Then create a "controls" window named "c" and create 
two buttons and two sliders in it. The "actions" defined for the buttons 
and sliders are functions (def's) to be executed when a button comes up or 
when a slider is dragged. In the while loop, c.interact() checks for mouse 
interactions on buttons or sliders, updates their appearances, and performs 
the actions specified. The slider "value" attribute gives the 
floating-point location along the slider, whose default min and max are 
0-100. The effect is that you can control the speed and direction of the 
cube's rotation. Just for fun, the sliders are coupled together: changing 
one changes the other. The coordinate system for setting up the buttons and 
sliders has the origin in the lower left corner, and the upper right corner 
is (100,100).

The point of the exercise is to seek your comments on this proposed module 
for a VPython-based set of controls. The actual appearances of the buttons 
and sliders can obviously be improved. The key issues are whether this 
"interact" scheme looks good, useful, and easy to teach and use.

Bruce Sherwood

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from visual import *
display(x=300, y=0, range=3, forward=-vector(0,1,1), newzoom=1)
cube = box(color=color.red)

c = controls()
bl = button(y=60, text='Left', action='setdir(1.)')
br = button(x=50, y=60, text='Right', action='setdir(-1.)')
hs = hslider(x=40, y=20, width=10, length=60, action='hsetrate()')
vs = vslider(x=20, y=0, width=10, length=50, action='vsetrate()')

def setdir(direction): # called on button up events
    cube.dir = direction

def setrate(value):
    cube.dtheta = 2.*value*pi/1e4

def hsetrate(): # called on hslider drag events
    setrate(hs.value) # hs.value is 0-100 slider position
    vs.value = hs.value # demonstrate making both sliders read alike

def vsetrate(): # called on vslider drag events
    setrate(vs.value) # vs.value is 0-100 slider position
    hs.value = vs.value # demonstrate making both sliders read alike

hs.value = 70. # mimic dragging the slider
hsetrate()
setdir(-1.)

while 1:
    rate(100)
    c.interact() # check for events, drive actions
    cube.rotate(axis=(0,1,0), angle=cube.dir*cube.dtheta)