Problems with plotting multiple objects over each other

I'm using the rectangle function to fill in a circle located at the center point (x,y) of a grid square and width and weigth (1,1) with curvature (1,1)...in other words a circle that touches the bounds of a grid square. This happens whenever I left click on the plot. I want to be able to right click in a grid square a have the filled in circle erase. For some reason Matlab won't overlay rectangles with the same center point. I was hoping to use the rectangle function again but with a black color (since my background is black). Once I get this part working, I want to extend it to replace any circle I click on with another circle of a different color I've picked already. Is there work around that I could use?

[Jan]

I do not understand the question. What does this mean: "have the filled in circle erase"? Or "For some reason Matlab won't overlay rectangles with the same center point."?

[Harold]

What I mean is I want to be able to delete the filled circle when I right click on it or if I left click on it with a different color selected. For example, in the picture here http://i50.tinypic.com/23if88j.jpg I first selected the blue color and left clicked on the grid squares. I then change to the red color and click on the grid squares. That blue circle should of been replaced with a red circle when I left clicked on it. I have the same problem when I try to right click on the circle. When I right click within the bounds of a grid square, the circle should be replaced with a circle colored in black (essentially erasing that circle from the board).

Answer 1

[Wouter]

You could try to edit the renderer of the figure window:

 set(gcf,'renderer','opengl') % changes the renderer of the current fig to opengl
 set(gcf,'renderer','painters') %changes the renderer to painters
 set(gcf,'renderer','zbuffer') %changes the renderer to buffer

A different renderer might be able to get rid of your visualisation problems.

[Harold]

Wouter,

Unfortunately editing the renderer did not work.

Answer 2

[Image Analyst]

When you call rectangle, store the handle of it in a 6 by 6 array at the location of the circle in the grid. Then when you have to change the color, delete the handle before drawing the new one.

% Draw.
handleArray(row, column) = rectangle(.....

When it comes time to draw a new circle of a different color:

% Erase that handle to clear the circle.
delete(handleArray(row, column));

% Draw new circle at that location.
handleArray(row, column) = rectangle(.....

[Harold]

I am trying to implement this code and I seem to be encountering a problem. When I right click in a grid square that has a circle, nothing happens. If I right click in a grid square that does not have a circle, an error appears stating "Invalid or deleted object". Which makes sense since there is no data to be deleted at that particular (row,col). I have no clue as to why your code is not working when there is a right click action in a grid square that contains a circle. I think the problem has to do with checking the button type.

Edit: Another problem I am having is that if I try and draw more than one circle of the same color one after the other, only the handle of the last circle drawn is kept in the array. Also, if I try and left click on a circle that already contains a circle the old circle will not get replaced by the new color choice.

As of now this is my code structure:

1) Get position of mouse in the figure.

2) If mouse is within bounds of axis (by comparing mouse location in figure to axis bounds by get(gca,'Position')), call @select_point.

3) Logic condition within select_point.m

 if strcmp(btn_type,'normal')

    handleArray(row_num, col_num) = rectangle...
    hold on
 elseif strcmp(btn_type,'alt')
    delete(handleArray(row_num, col_num))
 end

4) Plot grid lines using plot_grid.m. The variable div sets how many divisions each side of the grid will have. I decided to make my own grid due to resizing issues.

 function plot_grid(div)

 % specify the minor grid vector
 xg = [0:1:div];
 % specify the Y-position and the height of minor grids
 yg = [0:1:div];

 %vertical lines
 x = repmat(xg,length(xg),1);
 y = repmat(flipud(yg'),1,length(yg));

 plot([x,x'],[y,y'],'w')
 set(gca,'Color',[0, 0, 0]);
 set(gca, 'XTick',[]);
 set(gca, 'YTick',[]);
 box off
 axis square

[Harold]

No other suggestions? If you would like here is the fully developed code as of thus far. Flow_FreeGUI is the main program that you should run.

http://www42.zippyshare.com/v/12054401/file.html