Obtaining 3-d polygon in Matlab, by picking points.

I need to plot am extensive framework of 3d polygons in Matlab. putting point values and then drawing is a very cumbersome task. Is there any way that I can do this thing by either picking points in 3-d (like in paintbrush) ? Or any other alternate software and then export in matlab?

Answer 1

[Shivaputra Narke]

NumOfPoints=10; hax=gca; axis([0 10 0 5]) [x y] =ginput(NumOfPoints); plot(x,y);

[Archak Goel]

Thanks Mr. Narke. But can I do for 3-d space? This technique is limited to 2-d selection. I tried to modify your code for 3-d, the result was whatever I was selecting it was getting selected at z = 1 plane. Is there any way to define the plane in which we want to do the selection? How can I view the points as I am doing selection?

[Shivaputra Narke]

Yes you can do it for 3-D also but you have to write 'ButtonDownFcn' for axes that you are going to use.That involves pretty much lengthy code.

for your second question that is viewing selected points...

use following code,

NumOfPoints=10; hax=gca; axis([0 10 0 5]) ; hold on; allX=zeros(1,NumOfPoints); allY=zeros(1,NumOfPoints); vertices=[]; for i=1:NumOfPoints [x y] =ginput(1); plot(x,y,'ro'); vertices=[vertices;x y]; end cla; plot(vertices(:,1),vertices(:,2));

Answer 2

[Shivaputra Narke]

Hope this help you... use following code... function MainPlotPoly global POINTS POINTS=[]; hax=gca; axis([0 10 0 10 -5 5]) set(hax,'NextPlot','add'); grid on; set(hax,'ButtonDownFcn',@PlotPoly);

function PlotPoly(varargin)

global POINTS Cp=get(varargin{1},'CurrentPoint'); POINTS=[POINTS;Cp]; plot3(POINTS(:,1),POINTS(:,2),POINTS(:,3),'Marker','O');

Answer 3

[Matt J]

You can use PLOTREGION, possibly in conjunction with VERT2LCON , if you don't know the polyhedron in inequality form.