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<h3 class="subsection"> 4.9.6 Camera Movement </h3>
<p>This section describes how to move the camera.
</p>
<a name="1"></a>
<h4 class="subsubheading"> The Camera is a Transform </h4>
<p>Internally in the engine the <samp>‘csCamera’</samp> class inherits
directly from <samp>‘csOrthoTransform’</samp> which inherits from
<samp>‘csReversibleTransform’</samp>. If you work with <samp>‘iCamera’</samp> then you
can get the reference to this transform with <code>camera->GetTransform()</code>.
In addition to the transformation a camera also holds a pointer to the
current sector.
</p>
<p>This means that all operations you have in <samp>‘csOrthoTransform’</samp> can
be used on the camera. One of the most useful functions there is
<code>LookAt()</code> with which you can make the camera point to some spot.
Using <code>LookAt()</code> it is very easy to make a 3rd person view.
</p>
<p>In addition to the standard functions from <samp>‘csOrthoTransform’</samp> there
are a number of other functions that you can use. The most interesting
are <code>MoveWorld()</code> and <code>Move()</code>. These functions will move
the camera and make sure that it cannot walk through a wall and also make
sure that walking through portals will work. Both functions move the
camera a relative amount. The difference between <code>MoveWorld()</code> and
<code>Move()</code> is that the latter will move the camera in camera space.
For example, take the following code:
</p>
<table><tr><td> </td><td><pre class="example">iCamera* camera;
camera->GetTransform ().Move (csVector3 (0, 0, 1));
</pre></td></tr></table>
<p>This will move the camera forward in camera space. This means that the
camera will walk 'forward' :-) On the other hand:
</p>
<table><tr><td> </td><td><pre class="example">iCamera* camera;
camera->GetTransform ().MoveWorld (csVector3 (0, 0, 1));
</pre></td></tr></table>
<p>This will move the camera in the world so that it goes one unit in
the positive Z direction. This will happen independently of the orientation
of the camera.
</p>
<p>Here is another example which demonstrates how to use the <code>LookAt()</code>
function. The following example will set a camera at location <samp>‘3,5,1’</samp>
and let it look at <samp>‘3,5,10’</samp>. The up vector of the camera will be
<samp>‘0,1,0’</samp> (which is default):
</p>
<table><tr><td> </td><td><pre class="example">csVector3 camera_pos (3, 5, 1);
csVector3 look_at_pos (3, 5, 10);
csVector3 up (0, 1, 0);
camera->GetTransform ().Move (camera_pos);
camera->GetTransform ().LookAt (look_at_pos - camera_pos, up);
</pre></td></tr></table>
<a name="2"></a>
<h4 class="subsubheading"> Include Files </h4>
<p>The include files useful for this section are:
</p>
<table><tr><td> </td><td><pre class="example">#include <iengine/camera.h>
#include <csgeom/transfrm.h>
</pre></td></tr></table>
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