add btFileUtils::toLower to convert a string (char*) to lower case

URDF import demo: add COLLADA .dae file support
add FiniteElementMethod demo, extracted from the OpenTissue library (under the zlib license)
don't crash if loading an invalid STL file
add comparison with Assimp for COLLADA file loading (disabled by default, to avoid library dependency)
Gwen: disable some flags that make the build incompatible

Demos3/FiniteElementMethod/OpenTissue/utility/utility_material.h

@@ -0,0 +1,108 @@
+#ifndef OPENTISSUE_UTILITY_UTILITY_MATERIAL_H
+#define OPENTISSUE_UTILITY_UTILITY_MATERIAL_H
+//
+// OpenTissue Template Library
+// - A generic toolbox for physics-based modeling and simulation.
+// Copyright (C) 2008 Department of Computer Science, University of Copenhagen.
+//
+// OTTL is licensed under zlib: http://opensource.org/licenses/zlib-license.php
+//
+#include <OpenTissue/configuration.h>
+
+namespace OpenTissue
+{
+  namespace utility
+  {
+
+    /**
+    * A Material.
+    * This class encapsulates openGL material parameters.
+    */
+    class Material
+    {
+    protected:
+
+      float m_ambient[ 4 ];   ///< The ambient color rgba.
+      float m_diffuse[ 4 ];   ///< The diffuse color rgba.
+      float m_specular[ 4 ];  ///< The specular color rgba.
+      float m_shininess;      ///< The shininess of this material 0..180.
+
+    public:
+
+      Material()
+        : m_shininess(128)
+      {
+        set_default();
+      }
+
+      void ambient( float const & red, float const & green, float const & blue, float const & alpha = 1.0f )
+      {
+        m_ambient[ 0 ] = red;
+        m_ambient[ 1 ] = green;
+        m_ambient[ 2 ] = blue;
+        m_ambient[ 3 ] = alpha;
+      }
+
+      void diffuse( float const & red, float const & green, float const & blue, float const & alpha = 1.0f )
+      {
+        m_diffuse[ 0 ] = red;
+        m_diffuse[ 1 ] = green;
+        m_diffuse[ 2 ] = blue;
+        m_diffuse[ 3 ] = alpha;
+      }
+
+      void specular( float const & red, float const & green, float const & blue, float const & alpha = 1.0f )
+      {
+        m_specular[ 0 ] = red;
+        m_specular[ 1 ] = green;
+        m_specular[ 2 ] = blue;
+        m_specular[ 3 ] = alpha;
+      }
+
+      void shininess( float const & value )
+      {
+        m_shininess = value;
+      }
+
+      /*
+      void use()
+      {
+      if ( glIsEnabled( GL_COLOR_MATERIAL ) || !glIsEnabled( GL_LIGHTING ) )
+      {
+      glColor4f( m_diffuse[ 0 ], m_diffuse[ 1 ], m_diffuse[ 2 ], m_diffuse[ 3 ] );
+      }
+      else
+      {
+      glMaterialfv( GL_FRONT_AND_BACK, GL_AMBIENT,   m_ambient    );
+      glMaterialfv( GL_FRONT_AND_BACK, GL_DIFFUSE,   m_diffuse    );
+      glMaterialfv( GL_FRONT_AND_BACK, GL_SPECULAR,  m_specular   );
+      glMaterialfv( GL_FRONT_AND_BACK, GL_SHININESS, &m_shininess );
+      }
+      }
+      */
+
+      void set_default()
+      {
+        m_ambient[ 0 ]  = 0.1f;
+        m_ambient[ 1 ]  = 0.1f;
+        m_ambient[ 2 ]  = 0.0f;
+        m_ambient[ 3 ]  = 1.0f;
+        m_diffuse[ 0 ]  = 0.6f;
+        m_diffuse[ 1 ]  = 0.6f;
+        m_diffuse[ 2 ]  = 0.1f;
+        m_diffuse[ 3 ]  = 1.0f;
+        m_specular[ 0 ] = 1.0f;
+        m_specular[ 1 ] = 1.0f;
+        m_specular[ 2 ] = 0.75f;
+        m_specular[ 3 ] = 1.0f;
+        m_shininess     = 128;
+      }
+
+    };
+
+  } // namespace utility
+
+} // namespace OpenTissue
+
+//OPENTISSUE_UTILITY_UTILITY_MATERIAL_H
+#endif