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diff --git a/debian/fireflies/fireflies-2.08/libgfx/doc/rotate.html b/debian/fireflies/fireflies-2.08/libgfx/doc/rotate.html new file mode 100644 index 00000000..dc444409 --- /dev/null +++ b/debian/fireflies/fireflies-2.08/libgfx/doc/rotate.html @@ -0,0 +1,107 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" + "http://www.w3.org/TR/REC-html40/loose.dtd"> +<!-- $Id: rotate.html 309 2002-03-11 21:17:15Z garland $ --> + +<html> + +<head> +<title>libgfx: Interactive Rotation Control</title> +<link rel=stylesheet href="cdoc.css" type="text/css"> +<meta name="Author" content="Michael Garland"> +</head> + +<body> + +<h2>Interactive Rotation Control</h2> + +<p>The <tt>libgfx</tt> library provides a fairly simple facility for +interactive inspection of 3-D objects. The interface is designed +for applications where a user is inspecting an object by spinning it and +by translating the camera to provide a better view. All of the user +interaction is implemented through mouse motion: +<ul> + <li>Left mouse drag — rotate object about its centroid + <li>Right mouse drag — translate camera forward/backward + <li>Middle mouse drag — translate camera parallel to image plane +</ul> + +<p>The classes used to implement this functionality are based on a +fairly standard paradigm. Two subsequent mouse positions are projected +onto a notional surface "below" the window. The cross product of these +projected vectors defines an axis of rotation and the angle between them +defines the rotation angle. + +<h3>Ball Types</h3> + +<p>The library currently supports two control classes: + +<blockquote> + +<p><b>Arcball</b> The Arcball controller is based on the +article <i>Arcball Rotation Control</i> written by Ken Shoemake in +<i>Graphics Gems IV</i> published by Academic Press. +The underlying surface of projection is a hemisphere. + +<p><b>Trackball</b> Implements the mechanism used in the SGI +3-D demo programs. This approach was originally developed by Gavin +Bell. The underlying surface of projection is a hybrid of a hemisphere +and a hyperbolic sheet. +</blockquote> + +<h3>Public Interface</h3> + +<p>The two controller types both implement the same public interface, +and can be freely interchanged in the application program. The +interfaces for these controllers are defined in the following header +files: +<ul> + <li><tt>class Arcball</tt> — <tt><gfx/arcball.h></tt> + <li><tt>class Trackball</tt> — <tt><gfx/trackball.h></tt> +</ul> +To use one of the controllers, you need to include the appropriate +header and create an instance of the appropriate class. + +<h4>Initialization</h4> + +<p>Before using a rotation controller, you must initialize it by +providing the bounding sphere of the object to be controlled. This is +done using the templated method: +<pre> + template<class T> + void bounding_sphere(const TVec3<T>& center, T radius); +</pre> +The specified sphere <tt>center</tt> will be the point about which the +object will rotate. + +<h4>Interaction</h4> + +<p>Once initialized, the controller is meant to be interfaced directly +with the event handlers of an application built using the +<tt>libgfx</tt> <a href="gui.html">GUI framework</a>. +Each of the following controller methods should be called from the event +handlers of your application. +<pre> + virtual void update_animation(); + virtual bool mouse_down(int *where, int which); + virtual bool mouse_up(int *where, int which); + virtual bool mouse_drag(int *where, int *last, int which); +</pre> + +<h4>Applying Results</h4> + +<p>For the rotation to take effect, you must apply it in the rendering +loop of the application. Before drawing your scene, you should call the +method: +<pre> + virtual void apply_transform(); +</pre> +This will set up the appropriate transform on the <tt>ModelView</tt> +matrix stack. Similarly, when done drawing, you should call the method: +<pre> + virtual void unapply_transform(); +</pre> +which will clean up the <tt>ModelView</tt> matrix stack. + +</body> + +</html> |