VRweb Display Settings

VRweb

Jump to: Drawing Style, Render Mode/Stereo Rendering, Display Options, Lighting Options, Gamma Correction, Transparency, Texturing, Anchor Settings, Color Selection


Drawing Style

In the first part of the Display menu you can select the display mode:

A similar pullright menu is available for the interactive display mode, which is applied during navigation.
(use the accelerator keys above, holding both the shift and ctrl key)

An extra item "the same" uses the same display mode during navigation and for still images.
(accelerator key ctrl-u)

The default display mode is Smooth Shading, meaning you have to change to Texturing yourself to display or load textures. The Mesa version by default uses Flat Shading and Wireframe during navigation.


Render Mode

You can choose between (classical) Depth Buffer Rendering (accelerator key shift-D or shift-Z) and (new) BSP Tree (accelerator key shift-B). BSP (Binary Space Partitioning) does a presorting of all polygons to eliminate Z-buffer usage and therefore gains speed.

The first two BSP alternatives differ in rendering of two-sided or single-sided polygons. The third one, Shadow Volume BSP, incorporates visibility calculations to render only that part of the scene which is in the current field of view and not hidden by other polygons (see also navigation settings).

There are still some bugs in the BSP implementation and not all VRweb features are supported in BSP mode (e.g. no texture mapping, no AsciiText).

Stereo Rendering

Stereo rendering via red-green (actually red-cyan) images can be activated with the accelerator key shift-S or in the render mode pullright. To view it you need a pair of red-green or red-blue glasses (use the red glass for the left eye, or specify Xattributes otherwise).

Eye convergence and distance can be configured in the navigation settings dialog.

Normally, the red and cyan parts of all colors are filtered out, so that you get a (reduced) color impression of the original drawing (including shading and textures). Only wireframes in the Mesa version are drawn as plain red/cyan lines for speed (which you can also achieve selecting the "no materials" option of the lighting options). Background color is automatically switched to black.


Display Options


Lighting Options

Gamma Correction

If you use the Mesa version, you can set up gamma correction to brighten up the drawings. You have to set the environment variable MESA_GAMMA before starting VRweb. Some examples for uniform and non-uniform (RGB separately) gamma correction and deactivating it (depends on shell used):

   [csh/tcsh etc.:]  setenv MESA_GAMMA 2.0
                     setenv MESA_GAMMA "1.6 1.7 1.9"
                     unsetenv MESA_GAMMA
[sh/ksh/bash etc.:]  MESA_GAMMA=2.0 ; export MESA_GAMMA
                     MESA_GAMMA="1.6 1.7 1.9" ; export MESA_GAMMA
                     unset MESA_GAMMA

SGI supports gamma correction via the Xserver (see man gamma), so there is no need to do it in Software. OpenGL itself provides no way to change gamma.


Transparency

You may choose between the two transparency methods "stipple" and "blending" or ignore any transparency information (off). You may also toggle transparency calculations for texture images.


Texturing

Supported texture image formats are JPEG, GIF, TIFF, PNG, and VRML inline-textures. Transparent textures (GIF, PNG, inline) are supported also.

Common platform specific formats like SGI/RGB and BMP may be supported in a future version - their use is discouraged for cross platform portability and because of their poor compression (also TIFF falls into this category).

Texture transfer is initiated when switching the drawing mode to texturing (ctrl-t). The right field of the status line contains the hint "textured" if there are any texture references in the scene. For more details on transfer issues see description for inline scenes. For antialiasing, lighting, and transparency settings for textures see above.


Anchor Settings

These options concern anchor display and appearance.

Display (accelerator key F9) toggles anchor highlighting.
Also available as button in the toolbar.

The effect of the different hightlighting methods are also described on the anchor page.


Color Selection

Via Choose... you can open a dialog for interactive color selection. In the listbox in the top-right select the color you wish to change:

You can use the RGB or HLS color space for selections. Values can be changed with the sliders or by typing in the new values and entering Return. The field on the left side contains a predefined color map to choose from. With the Apply button you can test the changes; when finished, confirm them with OK or press Cancel to reject all changes.

The other menu items contain a few predefined colors, e.g. for quick change of the background color to black, grey, lightgrey or white.


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