A simple example of how to plot BOIDs or other agents on a plot in MATLAB

draw_boids.m

function Plot = draw( Plot )
	% Author: Douglas Stridsberg <d@stridsberg.uk>
	%
	% INFO
	% Redraws the plot, one BOID at a time.
	% Intended to be run once every frame. The Plot object requires
	% - an array of handles to old BOIDs created;
	% - an array of BOID objects. These, in turn, require
	%  - position vectors.
	% 
	% INPUT PARAMETERS
	% Plot - an object consisting of the following properties:
	%          - Boids: array of your boids (see the code for hints on what they should contain)
	%          - Plot_Handles: array of figure handles
	%
	% How you choose to implement this is up to you. This is not a working prototype per se, it is more a proof of concept.
	% Look at what's been done and take away what you need for your project to work, is my suggestion!
	
	% Clear current plot of old BOIDs
	for i = 1:length( Plot.Plot_Handles )
		if Plot.Plot_Handles(i) ~= 0		% we don't want to delete the root object!
			delete( Plot.Plot_Handles(i) );
		end
	end
	Plot.Plot_Handles = [ ];
	
	% Read BOID icon
	[ img_boid, ~, alpha_boid ]	= imread('gfx/icon_boid.png');
	
	% Resize BOID icon
	scale = 1.0;
	img_boid = imresize( img_boid, scale, 'lanczos3' );
	alpha_boid = imresize( alpha_boid, scale, 'lanczos3' );
	
	% Finds all BOIDs' positions
	for i = 1:length( Plot.Boids )
		
		% Reference a particular BOID
		Boid = Plot.Boids{i};
		
		% (OPTIONAL) Rotate the icon if you need this
		angle = -1 * get_vector_angle( Boid.Velocity_n ) - 90;		% imrotate rotates ccw
		img_i = imrotate( img_craft, angle );
		alpha_i = imrotate( alpha_craft, angle );
		
		% Plot the image onto the figure
		%
		% My icon size was 30x30 pixels, so my icon is on the middle of
		%  the BOID at coordinates -15, -15
		Plot.Plot_Handles(i) = image( Boid.Position(1)-15, Boid.Position(2)-15, img_i );
		
		% Set alpha data to enable transparency
		set( Plot.Plot_Handles(i), 'AlphaData', alpha_i );
		
	end
	
	% Redraw plot
	drawnow;

end