%% Create Custom State Space Validator for Path Planning
% This example shows how to use the createPlanningTemplate function to generate a template for customizing your own state validation class. State validation is used with path planning algorithms to ensure valid paths. The template function provides a basic implementation for example purposes.
% Call the create template function. This function generates a class definition file for you to modify for your own implementation. Save this file.
% createPlanningTemplate("StateValidator")
%
%% Class and Property Definition
% The first part of the template specifies the class definition and any properties for the class. Derive from the nav.StateValidator class. You can specify any additional user-defined properties here.
% classdef MyCustomStateValidator < nav.StateValidator & ...
%         matlabshared.planning.internal.EnforceScalarHandle
%     properties
%        % User-defined properties
%     end
% Save your custom state validator class and ensure your file name matches the class name.
%
%% Class Constructor
% Use the constructor to set the name of the state space validator and specify the state space object. Set a default value for the state space if one is not provided. Call the constructor of the base class. Initialize any other user-defined properties. This example uses a default of MyCustomStateSpace, which was illustrated in the previous example.
% methods
%         function obj = MyCustomStateValidator(space)
%             narginchk(0,1)
%
%             if nargin == 0
%                 space = MyCustomStateSpace;
%             end
%
%             obj@nav.StateValidator(space);
%
%            % Initialize user-defined properties
%         end
%
%% Copy Semantics
% Specify the copy method definition. Copy all the values of your user-defined variables into a new object, so copyObj is a deep copy. The default behavior given in this example creates a new copy of the object with the same type.
%         function copyObj = copy(obj)
%             copyObj = feval(class(obj), obj.StateSpace);
%         end
%
%% Check State Validity
% Define how a given state is validated. The state input can either be a single row vector, or a matrix of row vectors for multiple states. Customize this function for any special validation behavior for your state space like collision checking against obstacles.
%         function isValid = isStateValid(obj, state)
%             narginchk(2,2);
%             nav.internal.validation.validateStateMatrix(state, nan, obj.StateSpace.NumStateVariables, ...
%                 "isStateValid", "state");
%
%             bounds = obj.StateSpace.StateBounds';
%             inBounds = state >= bounds(1,:) & state <= bounds(2,:);
%             isValid = all(inBounds, 2);
%
%         end
%
%% Check Motion Validity
% Define how to generate the motion between states and determine if it is valid. For this example, use linspace to evenly interpolate between states and check if these states are valid using isStateValid. Customize this function to sample between states or consider other analytical methods for determining if a vehicle can move between given states.
%         function [isValid, lastValid] = isMotionValid(obj, state1, state2)
%             narginchk(3,3);
%             state1 = nav.internal.validation.validateStateVector(state1, ...
%                 obj.StateSpace.NumStateVariables, "isMotionValid", "state1");
%             state2 = nav.internal.validation.validateStateVector(state2, ...
%                 obj.StateSpace.NumStateVariables, "isMotionValid", "state2");
%
%             if (~obj.isStateValid(state1))
%                 error("statevalidator:StartStateInvalid", "The start state of the motion is invalid.");
%             end
%
%             % Interpolate at a fixed interval between states and check state validity
%             numInterpPoints = 100;
%             interpStates = obj.StateSpace.interpolate(state1, state2, linspace(0,1,numInterpPoints));
%             interpValid = obj.isStateValid(interpStates);
%
%             % Look for invalid states. Set lastValid state to index-1.
%             firstInvalidIdx = find(~interpValid, 1);
%             if isempty(firstInvalidIdx)
%                 isValid = true;
%                 lastValid = state2;
%             else
%                 isValid = false;
%                 lastValid = interpStates(firstInvalidIdx-1,:);
%             end
%
%         end
%
% Terminate the methods and class sections.
%     end
% end
% Save your state space validator class definition. You can now use the class constructor to create an object for validation of states for a given state space.
% Copyright 2019 The MathWorks, Inc.
%