function buildPRM(L1, L2, nbPoints)
%%%%%%%%%%%%%%%%%%
%function buildPRM(L1, L2, nbPoints)
% ex. buildPRM(2000, 1000, 10)
%
% Inputs:
%	-L1: lenght of the first link (in mm)
%	-L2: length of the second link (in mm)
%	-nbPoints: the number of valid points in the roadmap
%
% Outputs: None
%
% author: Guillaume Gibert, guillaume.gibert@ecam.fr
% date: 22/11/2023
%%%%%%%%%%%%%%%%%%

q1q2_valid = [];
counter = 0;

% creates a figure
figure;

while (size(q1q2_valid,2) < nbPoints)
	% samples randomly the joint space
	q1 = rand()*360.0;
	q2 = rand()*360.0;
	
	% creates the DH table
	theta = [q1; q2];
	d = [0; 0];
	a = [L1; L2];
	alpha = [0; 0];

	% computes the FK
	wTee = dh2ForwardKinematics(theta, d, a, alpha, 1);

	% determines the position of the end-effector
	position_ee = wTee(1:2,end);
	
	% checks if the end-effector is not hitting any obstacle
	eeHittingObstacle = 0;
	if (position_ee(2) >= L1)
		eeHittingObstacle = 1;
	end
	if (position_ee(2) <= -L1)
		eeHittingObstacle = 1;
	end
	if (position_ee(1) >= -L2 && position_ee(1) <= L2 && position_ee(2) >= -L2 && position_ee(2) <= L2)
		eeHittingObstacle = 1;
	end
		
	% stores these random values
	if (eeHittingObstacle == 0)
		q1q2_valid = [q1q2_valid theta];
		
		% plots the new valid sample
		%subplot(1,2,1);
		%plot(q1,q2, '+g'); hold on; 
		%subplot(1,2,2);
		plot(position_ee(1),position_ee(2), '+g'); hold on; 
	else
		% plots the new invalid sample
		%subplot(1,2,1);
		%plot(q1,q2, '*r'); hold on; 
		%subplot(1,2,2);
		plot(position_ee(1),position_ee(2), '*r'); hold on; 
	end
	
	counter = counter + 1;
end

% displays stats
fprintf("%d points were sorted to achieve %d valid points\n", counter, nbPoints)

% add limits, lables and obstacles to the map
%subplot(1,2,1);
%	xlim([0 360]);
%	ylim([0 360]);
	
%	xlabel('q1(deg)');
%	ylabel('q2(deg)');
%	title('Joint space');
	
%subplot(1,2,2);

	plot([-L2; L2], [L2; L2], 'r'); hold on;
	plot([L2; L2], [L2; -L2], 'r'); hold on;
	plot([L2; -L2], [-L2; -L2], 'r'); hold on;
	plot([-L2; -L2], [-L2; L2], 'r'); hold on;
	
	plot([-(L1+L2); L1+L2], [L1 ; L1], 'r'); hold on;
	plot([-(L1+L2); L1+L2], [-L1 ; -L1], 'r'); hold on;
	
	drawCircle(0,0, L1+L2);
	drawCircle(0,0, L1-L2);
	
	xlim([-(L1+L2) (L1+L2)]);
	ylim([-(L1+L2) (L1+L2)]);
	
	xlabel('x(mm)');
	ylabel('y(mm)');
	title('Cartesian space');

% creates a connection map
connectionMap = zeros(nbPoints, nbPoints);

for l=1:size(q1q2_valid,2)
	for m=1:size(q1q2_valid,2)
		if (l ~=m)
			% creates the DH table
			theta = q1q2_valid(:,l);
			d = [0; 0];
			a = [L1; L2];
			alpha = [0; 0];
			% computes the FK
			wTee = dh2ForwardKinematics(theta, d, a, alpha, 1);
			A = wTee(1:2,end);
			
			% creates the DH table
			theta = q1q2_valid(:,m);
			d = [0; 0];
			a = [L1; L2];
			alpha = [0; 0];
			% computes the FK
			wTee = dh2ForwardKinematics(theta, d, a, alpha, 1);
			B = wTee(1:2,end);
			
			% computes y =ax + b
			
			% if no collision
			%connectionMap(l,m) = 1;
			% else
			%connectionMap(l,m) = 0;
		end	
	end
end