Develop Reference

Need help creating a code that instances an object along a surface evenly

I'm pretty new to coding and I need to create a code that generates an object along the normal of a selected geo surface.
Anything to start me on the right path would be appreciated.
I initially tried to use duplicate, but I was told that command instancer is the better option.
def ChainmailSurfaceGenerator():
thing = MC.ls(sl=True)
print thing
if not thing:
MC.error("select a torus")
#create a group for your chainmail*
grp = MC.group(empty=True, name=thing[0] + '_grp#'
#create hierarchy of grouped toruses
MC.polyTorus( radius=1, n = 'chainmail_link')
MC.duplicate('chainmail_link')
#query the direction of UV normals off the face
#lessen the amount of geometry if its too dense
#try it out on a plane surface first
#keep things simple early
#what if chains don't connect perfectly? add a randomizer so that the chains aren't all completely symmetrical
#don't use MC.duplicate; use Instancer

You might not actually need to query the UV direction of the target geometry.
Try looking into the commands for constraints like cmds.normalConstraint or cmds.geometryConstraint. As for the number of objects to make, consider using a for loop in a range of how many objects you want. If you want to apply a random rotation, I would recommend using a group or a locator as an offset for transforming the group around (either with setAttr or xform) so that you can move the group while maintaining the ability to rotate the duplicate in it's y axis. If you go the route of normal constraints, be sure to use the aim flag to point the object up in its y axis! Googling the commands should come up with documentation on what flags to use.

Looping an animation using Bokeh

I'm new to Bokeh and Python, and this is my first Stack Overflow question as well.
I'm using Bokeh to plot trajectory profiles of particles diffusing in the brain, but have it be animated. I have been able to successfully create a program that plots the points, but once all the points are plotted, it stops. I want to be able to loop the animation so that once all the points are plotted, it clears itself and starts over.
I am still very unfamiliar with coding terms, and I wasn't able to find something that could do this. I thought I was on the right track with importing using the reset function inside an if statement, but it doesn't seem to work. I have looked at the following as well for reference:
How to animate a circle using bokeh
Here is my code so far plotting a random trajectory:
import numpy as np
from bokeh.plotting import figure, show, gridplot, vplot, hplot, curdoc
from bokeh.io import output_notebook
from bokeh.client import push_session
from bokeh.core.state import State as new
# This is where the actual coding begins.
b = np.random.rand(300, 3)
xlist = b[:, 1]
ylist = b[:, 2]
# create a plot and style its properties. Change chart title here.
p = figure(title='PEG_PLGA15k_F68_R2_P81', title_text_font_size='13pt',
x_range=(min(xlist), max(xlist)), y_range=(min(ylist), max(ylist)),)
# add a text renderer to out plot (no data yet)
r = p.line(x=[], y=[], line_width=3, color='navy')
session = push_session(curdoc())
i = 0
ds = r.data_source
# create a callback that will add a number in a random location
def callback():
global i
ds.data['x'].append(xlist[i])
ds.data['y'].append(ylist[i])
ds.trigger('data', ds.data, ds.data)
if i < xlist.shape[0] - 1:
i = i + 1
else:
new.reset()
# Adds a new data point every 67 ms. Change at user's discretion.
curdoc().add_periodic_callback(callback, 67)
session.show()
session.loop_until_closed()

If all you want is to restart the animation once you reach some condition (like "all points have been plotted") you can just reset the DataSource. So, for instance, on your example you should have:
else:
i = 0
ds.data['x'] = []
ds.data['y'] = []
instead of:
else:
new.reset()
and that should do the trick. Just use your datasource... State is a more general component that should be used on different level and not to manage plot glyphs and datasources.
A couple of quick notes here:
On your question you've mentioned a link to the 0.10 version documentation but from your code I can tell you are not using a newer version (0.11.x). Always be sure to use the right docs for the version of Bokeh you are using since there might be a few changes between one version and another before the project reach 1.0.
You don't need to call ds.trigger('data', ds.data, ds.data) since bokeh property system will automatically detect your changes to the datasource fields inside your callback
You are designing/running your script as a bokeh script that uses a client session to the server (so you'll have a running instance of bokeh server somewhere and your script communicates with it). I'd suggest you to consider running your code as a Bokeh App instead, so your session and your code run inside the bokeh server instance. You can see more details about the difference at the bokeh server section on the official docs.

Maya Python - How do I query the selection to check if only polyVerts or different?

I have a bunch of poly vertex components selected. But sometimes users might select something else along with it (a joint, another mesh, etc.). I'm trying to find a way to test against everything selected to verify it is indeed a vertex. But I can't find anything like this.
Is there a python command to do this directly?

It may be useful for your use-case to use filterExpand with the selectionMask flag set to 31 to return just polygon vertex components from everything that has been selected.
Following is a simple sample (with some comments):
Try it out with different kind of objects and components selected.
import maya.cmds as cmds
# Will return EVERYTHING selected
all_selected = cmds.ls(sl=True)
# Will filter out and return just the verts
# from everything selected
just_the_selected_verts = cmds.filterExpand(sm=31)
Check out filterExpand in the docs here.

Not exactly. You can find objects which are ready for component selection with cmds.ls(hl=True). You can find selected object which aren't components with cmds.ls(o=True). That means you can isolate only the component selections indirectly like this:
set (cmds.ls(sl=True, o=False)) - set(cmds.ls(sl=True, o=True))
which makes a set of the whole selection, then one with only the objects, and finally subtracts the second from the first leaving only the component selections (note that will also pass attribute selections if you have those).

Real-time plotting in Python using pyqtgraph

I am writing an application in Python using Qt (currently PyQt) that receives telemetry (position data) over UDP and displays that data. It can handle several packet types each with several data fields each. I have a separate thread that handles receiving and decoding packets and they emits a signal to send that data to the Qt GUI for display. The data get displayed in several ways: a current value display, scrolling log display, and a 3D view display. All this runs great and in real time with each packet updating at up to about 30Hz.
I want to add another tab that shows a live plot. The user can select which data streams to plot and it will update in real time, showing a sliding window of the last 60sec of data (maybe configurable at some point). However my first approach is particularly slow. It is barely keeping up plotting only one line with our emulator that runs much slower than 30Hz.
I am using pyqtgraph to do the plotting. I have a PlotWidget instantiated in my .ui file and create a PlotDataItem for each data line that could be drawn on the plot. I am using deques to store the data to be plotted, both the value and the time. This way I can quickly add data as it comes in and remove it as it falls outside of the sliding window. I am storing all this in a dict for each packet type and field:
self.plotData[pktType][field] = {}
self.plotData[pktType][field]['curve'] = self.pwPlot.plot()
self.plotData[pktType][field]['starttime'] = time
self.plotData[pktType][field]['data'] = coll.deque()
self.plotData[pktType][field]['realtime'] = coll.deque()
self.plotData[pktType][field]['time'] = coll.deque()
'starttime' stores an initial datetime value for computing elapsed seconds. 'realtime' stores datetime values of when each packet was received (I am not currently using this, so I could drop it if it would save time). 'time' stores elapsed seconds from the 'starttime' for easier plotting and 'data' stores the values.
When a packet that comes in, I store data in the deques for each field I might want to parse. I then trim off any data outside the sliding window. Finally, the deque gets packaged in a numpy array and passed to the PlotDataItem setData method. Here's a simplified version of the code that runs for each received packet:
def updatePlot(self, time, pktData):
pktType = pktData['ptype']
keys = self.getPlottableFromType(pktType) # list of fields that can be plotted
if keys == None:
return
for k in keys:
self.plotData[pktType][k]['data'].append(pktData[k])
self.plotData[pktType][k]['realtime'].append(time)
runtime = (time - self.plotData[pktType][k]['starttime']).total_seconds()
if self.plotRate == 0:
self.plotData[pktType][k]['time'].append(runtime)
else:
if self.plotData[pktType][k]['time']: # has items
nexttime = self.plotData[pktType][k]['time'][-1] + 1. / self.plotRate
else:
nexttime = 0
self.plotData[pktType][k]['time'].append(nexttime)
while (self.plotData[pktType][k]['time'][-1] - self.plotData[pktType][k]['time'][0]) > self.plotRangeSec:
self.plotData[pktType][k]['data'].popleft()
self.plotData[pktType][k]['realtime'].popleft()
self.plotData[pktType][k]['time'].popleft()
self.drawPlot(pktType, k)
def drawPlot(self, pktType, k):
if self.plotIsEnabled(pktType, k) and self.plotData[pktType][k]['time']: # has items
npt = np.array(self.plotData[pktType][k]['time'])
npd = np.array(self.plotData[pktType][k]['data'])
self.plotData[pktType][k]['curve'].setData(npt, npd)
else:
self.plotData[pktType][k]['curve'].clear()
self.plotRate can be used to plot the data either using wall time or force the time axis to a fixed update rate. This is useful for using with the emulator since it runs slower than the real system.
First thing I should probably do is not call .clear() every time for plots that are not being plotted (just complicates the logic a little bit). Other than that, anyone have any tips for improving performance? Is the deque to numpy array a good strategy? Is there a better way to update the data since I am only changing a few values per line (adding a point and possibly removing a point or two)?

change bones position in a armature in blender game engine using python

I am working on real time mapping of model with the user data obtained from Kinect.
I am able to get access to the individual bone using bge.types.BL_ArmatureObject().channels
which give the list of bones. I am not able to change the position bone. I tried to use rotation_euler to give it some rotation but it had no effect. Please tell me how to do it.

Maybe a little late, but for blender >= 2.5 this should do the trick:
# Get the whole bge scene
scene = bge.logic.getCurrentScene()
# Helper vars for convenience
source = scene.objects
# Get the whole Armature
main_arm = source.get('NAME OF YOUR ARMATURE')
main_arm.channels['NAME OF THE BONE YOU WANT TO ROTATE'].joint_rotation[ x, y ,z] # x,y,z = FLOAT VALUE
main_arm.update()
I also wrote this down in an extensive tutorial, starting here: http://www.warp1337.com/content/blender-robotics-part-1-introduction-and-modelling