function vrcar %VRCAR Car in the mountains - the basic Virtual Reality Toolbox example. % The VRCAR example illustrates the use of the Virtual Reality Toolbox % MATLAB interface. In a step-by-step tutorial, it shows commands for % navigating a virtual car along a path through the mountains. % Copyright 1998-2003 HUMUSOFT s.r.o. and The MathWorks, Inc. % $Revision: 1.7.4.2 $ $Date: 2004/04/06 01:11:18 $ $Author: batserve $ disp('%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%'); disp('%%% %%%'); disp('%%% Welcome to the Virtual Reality Toolbox! %%%'); disp('%%% %%%'); disp('%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%'); disp(' '); disp('%%% In this example we will show you how to control an object in a virtual'); disp('%%% world using the MATLAB object-oriented interface.'); disp('%%%'); disp('%%% We begin with creating an object of class VRWORLD that represents'); disp('%%% the virtual world. The VRML file that constitutes the world was previously'); disp('%%% made by the V-Realm VRML builder contained in the Virtual Reality Toolbox.'); disp('%%% The name of the file is VRMOUNT.WRL.'); dispeval('world = vrworld(''vrmount.wrl'')'); disp('%%% The world must be opened before it can be used.'); disp('%%% This is accomplished by the OPEN command.'); dispeval('open(world);'); disp('%%% The virtual world can be viewed in the VRML viewer. Virtual Reality Toolbox'); disp('%%% offers two ways of viewing virtual worlds - internal viewer (default method)'); disp('%%% and external viewer, integrated with your Web browser (available on some platforms).'); disp('%%% We will view the virtual world in the viewer using the VIEW function.'); disp('%%% It may take some time before the viewer opens, so please be patient.'); dispeval('view(world);vrdrawnow;'); disp('%%% We can examine the properties of the virtual world by the GET command.'); disp('%%% Note the ''FileName'' and ''Description'' properties which contain the file name'); disp('%%% and description taken from the ''title'' property of the VRML file.'); disp('%%% Detailed description of all the properties is beyond the scope of this example'); disp('%%% but can be easily found in the VR Toolbox manual or in the online documentation.'); dispeval('get(world)'); disp('%%% All elements in a virtual world are represented by VRML nodes.'); disp('%%% Behaviour of any element can be controlled by changing the fields'); disp('%%% of the appropriate node (or nodes).'); disp('%%% The NODES command prints out a list of nodes available in the world.'); dispeval('nodes(world)'); disp('%%% To access a VRML node, an appropriate VRNODE object must be created.'); disp('%%% The node is identified by its name and the world it belongs to.'); disp('%%%'); disp('%%% We will create a VRNODE object associated with a VRML node ''Automobile'''); disp('%%% that represents the model of car on the road. If you don''t see it in the scene,'); disp('%%% don''t worry. It is hidden in the tunnel on the left.'); dispeval('car = vrnode(world, ''Automobile'')'); disp('%%% VRML fields of a given node can be queried by the FIELDS command.'); disp('%%% We''ll see that there are fields named ''translation'' and ''rotation'''); disp('%%% in the node list. We can move the car around by changing these fields.'); dispeval('fields(car)'); disp('%%% Now we prepare vectors of coordinates determining the car movement.'); disp('%%% By setting them in a loop we will create an animated scene.'); disp('%%% There are three sets of data for three phases of car movement.'); c1 = 'z1 = 0:12;\n x1 = 3 + zeros(size(z1));\n y1 = 0.25 + zeros(size(z1));\n'; c2 = '\n z2 = 12:26;\n x2 = 3:1.4285:23;\n y2 = 0.25 + zeros(size(z2));\n'; c3 = '\n x3 = 23:43;\n z3 = 26 + zeros(size(x3));\n y3 = 0.25 + zeros(size(z3));'; dispeval([c1 c2 c3]); disp('%%% Now let''s move the car along the first part of its trajectory.'); disp('%%% The car is moved by setting the ''translation'' field of the ''Automobile'' node.'); dispeval('for i=1:length(x1);\n car.translation = [x1(i) y1(i) z1(i)];vrdrawnow;\n pause(0.1);\n end;'); disp('%%% We''ll rotate the car a little to get to the second part of the road.'); disp('%%% This is done by setting the ''rotation'' property of the ''Automobile'' node.'); dispeval('car.rotation = [0, 1, 0, -0.7];vrdrawnow;'); disp('%%% Now we''ll pass the second road section.'); dispeval('for i=1:length(x2);\n car.translation = [x2(i) y2(i) z2(i)];vrdrawnow;\n pause(0.1);\n end;'); disp('%%% Finally, we turn the car to the left again ...'); dispeval('car.rotation = [0, 1, 0, 0];vrdrawnow;'); disp('%%% ... and let it move through the third part of the road.'); dispeval('for i=1:length(x3);\n car.translation = [x3(i) y3(i) z3(i)];vrdrawnow;\n pause(0.1);\n end;'); disp('%%% If we want to reset the scene to the original state'); disp('%%% defined in the VRML file, we can reload the world.'); dispeval('reload(world);vrdrawnow;'); disp('%%% After you are done with a VRWORLD object, it is necessary to close and delete it.'); disp('%%% This is accomplished by the CLOSE and DELETE commands.'); disp('%%%'); disp(' '); disp('>> close(world);'); disp('>> delete(world);'); disp(' '); disp('%%%'); disp('%%% However, we will not do it here. Instead, we leave the world open so that'); disp('%%% you can play with it further. You can try moving the car around using commands'); disp('%%% similar to those above, or you can try to access other nodes and their fields.'); disp('%%% We will clear only the used global variables.'); dispeval('clear ans car i x1 x2 x3 y1 y2 y3 z1 z2 z3;'); disp('%%%'); disp('%%% Congratulations! You have just finished the Virtual Reality Toolbox interactive tutorial.'); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % DISPEVAL % displays and evaluates a command % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% function dispeval(x) disp('%%%'); disp('%%% Press Enter to execute the command.'); x = sprintf(x); fprintf('\n>> %s\n\n', x); ignore = input('','s'); evalin('base', x); fprintf('\n');