Keeping axes still, while transforming objects

Hi,

in this ( https://www.youtube.com/watch?v=FrpG-KP_Tg8 ) video at the end, a transformation is applied. I have adopted the code from the video, but somehow my axes get scaled too. This is my code:

clc;
close all;
clear all;

comPort = '/dev/cu.usbmodem1421';
if(~exist('serialFlag','var'));
    [fsr.s,serialFlag] =  setupSerial(comPort);
end
if(~exist('h','var')|| ~ishandle(h))
    h = figure(1);
end
if(~exist('text1','var'))
    text1 = uicontrol('Style','text', 'String', 'X: 0 degress',...
        'pos',[450 100 100 25],'parent',h);
end
if(~exist('text2','var'))
    text2 = uicontrol('Style','text', 'String', 'Y: 0 degress',...
        'pos',[450 75 100 25],'parent',h);
end
if(~exist('button','var'))
    button = uicontrol('Style','togglebutton', 'String', 'Stop & Close Serial Port',...
        'pos',[0 0 200 25],'parent',h);
end

weights=[0 700 800 900 1000 1500 2000 2500 3000 4000 4999];
%Hier noch mehr hinzufuegen
m1 = zeros(length(weights),1);
length(weights)
%Read values for each weight and assign it 
for i=2:length(weights)
    mbox = msgbox(['Place ' num2str(weights(i)) ' grams on FSR.']); uiwait(mbox);
    m1(i)= readFSR(fsr)

      while (m1(i)<m1(i-1))
              m1(i)=readFSR(fsr);
      end
  end
  m=m1.';
  P1=polyfit(m,weights,2)
  %250 is the max weight. 250g. Change to 20 000!
  myaxes = axes('xlim',[-20 20],'ylim',[-20 20],'zlim',[0 6]);    
  view(3);
  grid on;
  axis equal;
  hold on;

%Draw sphere
[xsphere, ysphere, zsphere] = sphere();
h(1) = surface(xsphere,ysphere,zsphere);

combinedobject = hgtransform('parent',myaxes);
set(h,'parent',combinedobject)
drawnow

while (get(button,'Value')==0)
    [voltage]=readFSR(fsr);
    mass = polyval(P1,voltage); %in g
    if(mass>0)
        force = mass*9.81; %in newton
        set(text1,'String',['Mass: ' num2str(mass) ' g']);
        set(text2,'String',['Force: ' num2str(force) ' N']);

          translation = makehgtform('translate',[0 0 mass/1000]); %in kg's
          set(combinedobject,'matrix',translation);

          %Scale sphere
          scaling = makehgtform('scale', mass/10000);
          set(combinedobject,'matrix',scaling);

          set(combinedobject,'matrix',translation*scaling);
          drawnow
      end
      pause(0.1);
  end
  closeSerial;

[Walter Roberson]

http://www.matlabarduino.org/force.html is the source of the tutorial

Answer 1

[Tim Berk]

I can't reproduce this as your script won't run on its own, but I think the problem is that

axis equal

Overwrites the limits stated in

myaxes = axes('xlim',[-20 20],'ylim',[-20 20],'zlim',[0 6]);

You can solve this by reversing the order in which the axes limits and "axis equal" option are called, i.e.

myaxes = axes;    
view(3);
grid on;
axis equal;
axis([-20 20 -20 20 0 6])
hold on;

Cheers,

Tim