the contents of a frame drawn with pressed left mouse button.
<hr>
+\image html occ_view_fitselection.png
+
+<b>Fit selection</b> - fits view contents to the current selection.
+<hr>
+
\image html occ_view_zoom.png
<b>Zoom</b> - allows to zoom in and out.
<b>Rotate clockwise</b> - rotates view 90 @htmlonly ° @endhtmlonly clockwise.
<hr>
+\image html occ_view_orthographic.png
+
+<b>Ortographic projection</b> - default OCC viewer projection mode.
+<hr>
+
+\image html occ_view_perspective.png
+
+<b>Perspective projection</b> - perspective OCC viewer projection mode.
+<hr>
+
+\image html occ_view_stereo.png
+
+<b>Stereo projection</b> - stereoscopic rendering of the view.
+\note Activation of this mode also switches the view to perpective projection
+in case if the orthographic one has been active.
+\note By default, quad-buffered stereo is activated, if it is supported by the graphic card.
+If no stereo capabilities are available, an error message is shown.
+\note The stereoscopic view settings can be defined in
+\ref occ_preferences "OCC 3D Viewer" preferences.
+
+<hr>
+
\image html occ_view_reset.png
<b>Reset</b> - restores the default position (isometric) of objects in
the other view.
<hr>
+\image html occ_view_ray_tracing.png
+
+\anchor ray_tracing
+
+<b>Ray tracing</b> - allows to switch between rendering methods in run-time
+in the current OCCT 3D view. It can be used to produce images with photorealistic quality.
+
+\image html doc_ray_tracing.png
+
+- <b>Ray tracing</b> - specifies rendering mode: OpenGL rasterization (by default) or GPU ray-tracing.
+
+ - <b>Depth</b> - defines maximum ray-tracing depth.
+
+ - <b>Specular reflections</b> - enables/disables specular reflections.
+
+ - <b>Adaptive anti-aliasing</b> - enables/disables adaptive anti-aliasing.
+
+ - <b>Shadows rendering</b> - enables/disables shadows rendering.
+
+ - <b>Transparent shadow</b> - enables/disables light propagation through transparent media.
+
+<hr>
+
+\image html occ_view_env_texture.png
+\anchor env_texture
+
+<b>Environment texture</b> - allows to set parameters for environment texture.
+This is a special mode of texture mapping when specular reflection of environment texture
+is simulated by OpenGL using a special texture coordinates generation algorithm (a sphere map).
+
+\image html doc_env_texture.png
+
+- <b>Environment texture</b> - enables/disables environment texture in the current OCCT 3D view.
+
+User can select one of 7 predefined environment texture from the list or define its texture from file by
+choosing item <b>"Custom..."</b> in a combo box.
+
+\note Note that the environment texture file should normally satisfy the following requirements
+in order to produce good visual result:
+- The image file should have 2:1 width-to-height ratio.
+- It should constitute a 360-degrees panoramic image created using a fish-eye lens.
+
+<hr>
+
+\image html occ_view_light_source.png
+
+\anchor light_source
+
+<b>Light source</b> - allows to set parameters for light source.
+
+It's possible to choose a type of light source between directional and positional light.
+
+\image html doc_dir_light_source.png
+
+<b>Directional</b> light - creates a directional light source in the viewer.
+It is defined by direction coordinates, color and headlight parameter.
+
+\image html doc_pos_light_source.png
+
+<b>Positional</b> light - creates an isolated light source X,Y,Z in the viewer.
+It is also defined by the color and headlight parameter.
+
+Click:
+
+- <b>Apply and Close</b> to apply defined light source to the OCC 3D Viewer.
+
+- <b>Default</b> to restore default values of light source.
+
+- <b>Close</b> to return parameters of light source on initial values.
+
+<hr>
*/
