PowerStorm® 300/350 UNIX Graphics Support Release Notes

Preface

/usr/opt/3X0/ReleaseNotes/ReleaseNotes.html

1.1 Product Summary

• 3X0DEVICE422/522/523
  • Device-dependent libraries for the X server.
  • Kernel device driver for the PowerStorm 300 and PowerStorm 350 devices.
• 3X0GLBASE422/522/523
  • OpenGL direct-rendered graphics support libraries. These libraries are used by applications written to the OpenGL V1.1 and GLX V1.2 standards.

• Subset Version 523 supports Tru64 UNIX V5.1A
• Subset Version 522 supports Tru64 UNIX V5.0A and V5.1
• Subset Version 422 supports Tru64 UNIX V4.0F and V4.0G

1.1.1 Product Enhancements

1.1.2 Product Bug Fixes

• Using the non-thread safe version of the OpenGL library, after destroying one context and creating a new one, a segmentation fault was happening in the glXMakeCurrent call on the new context.
• When running in direct rendering mode and using the same gl context to render into two different windows, sometimes bitmaps were not being displayed.
• When running in indirect rendering mode and using the same gl context to render into two different windows, sometimes the display in one of the windows would be corrupted.
• When drawing polygons or triangles using polygon mode GL_LINE at the bottom and right edge of the gl viewport, extra lines would be drawn along the edge of the viewport.
• When using the Xserver's -screenOrder command line option to ignore one or more of the physical screens, sometimes there is a problem creating the context for a 3D application.
• When XFillRectangle was called with values outside of the window, the filled rectangle would not always get clipped. This resulted in pixels sometimes being displayed outside of the window.

1.2 Overlay Support

To get the visualIDs of the overlay visuals, you need to get the SERVER_OVERLAY_VISUALS property from the root window. To retrieve the property and interpret the data associated with it, consider the following example:

property_name: SERVER_OVERLAY_VISUALS
property_type: SERVER_OVERLAY_VISUALS
format: 32

SERVER_OVERLAY_VISUALS {
    overlay_visual: VISUALID
    transparent_type: {None, TransparentPixel, TransparentMask}
    value: CARD32
    layer: CARD32
}

You would typically receive the following information:

0x00000027  /* VisualID */
0x00000001  /* Indicates that the transparent_type is TransparentPixel */
0x00000000  /* The transparent pixel's value is 0 */
0x00000001  /* The layer is 1 */

Overlay windows and regular windows are in different layers, so drawing in an overlay window will not disturb the pixels of the regular window, and vice versa. If you draw a transparent pixel into an overlay window, the pixel of the non-overlay window beneath that window will show through.

Tru64 UNIX supplies the dtwm window manager, which provides an option to support overlays. Use the -Overlay command line option (dtwm -Overlay) to allow the window manager to take advantage of the overlay planes. When the window manager overlay option is enabled, the borders of windows in the overlay planes are created in the overlays as well. This reduces the number of expose events for applications that create menus or other windows in the overlays. Borders of windows in the main image planes still reside in the main image planes.

Tru64 UNIX also supplies a Motif window manager with an option to support overlays. However, this window manager overlay option (/usr/bin/X11/mwm -Overlay) has numerous problems and is not recommended or supported.

Applications should not install or deinstall colormaps themselves. The window manager should perform these actions. However, the application is responsible for providing the window manager with hints as to which colormaps to install or deinstall. You provide this information using the Xlib function XSetWMColormapWindows(). This function sets the WM_COLORMAP_WINDOWS property for a given window.

For information on how to use this function and how the window manager interprets the property, see X Window System by Scheifler and Gettys, 3rd Edition, Digital Press (Section 14.1.11, Setting and Reading the WM_COLORMAP_WINDOWS Property, pages 425-426, and Section 4.1.8, Colormaps, page 649-651).

Applications developed on systems with only one colormap may appear incorrect on systems with multiple colormaps. There are several application errors that can cause this, but the most prevalent is not having the correct colormap associated with all the windows that require it. To correct this problem, use XChangeWindowAttributes() to set the colormap for all windows in the application that require the colormap.

The supported number and configuration of multiple PowerStorm 300 and PowerStorm 350 boards vary by platform. Other documentation shipped with your workstation or server, or with your PowerStorm 300/350 option or driver software, will put specific limitations on the number and configuration of multihead support.

The PowerStorm 300/350 is not supported in conjunction with any other non-PowerStorm 300/350 graphics board residing in the system.

The X server command line option -screenOrder may be used to alter the mapping of physical screens to logical screens. In particular, this can be useful if you desire the X server's primary screen to coincide with the VGA console.

  +panoramiX
      Enables the PanoramiX extension which allows a system 
      with multiple video monitors to operate the monitors as 
      a single large screen.

  -panoramiX
      Disables the PanoramiX extension.

  +panoramiX
  -edge_bottom
  -edge_left
  -edge_right
  -edge_top
  -screenOrder

In order to take advantage of the unique features of the PowerStorm 350, such as stereo rendering or the enlarged texture cache, all heads in the PanoramiX configuration must be PowerStorm 350s. If any PowerStorm 300 is present, all PowerStorm 350s will behave like PowerStorm 300s.

Table 2-1: Supported Video Modes

As an example, to switch to 1280x1024 at 85Hz:

! PowerStorm 300/350 Server args start
       -pn -bs -su -nice -2 -screen 1280x1024 -vsync 85
! PowerStorm 300/350 Server args end

/usr/sbin/init.d/xlogin restart

1.5.1 Supported Stereo Resolutions on PowerStorm 350

To enable this synchronization, add the following device-dependent argument to the X server command-line arguments discussed above:

! PowerStorm 300/350 Server args start
       -pn -bs -su -nice -2 -I -riFlipVSync
! PowerStorm 300/350 Server args end

Note:
This synchronization will reduce performance on applications (including benchmarks!) which would otherwise have a frame rate that exceeds the refresh rate, in effect limiting the frame rate to the refresh rate. In some cases, the frame rate is further limited to half the refresh rate. In other words, a 60 Hz refresh rate with synchronization enabled will limit an application to roughly 30-60 frames per second.

In order to make 32-bit texels the default for generic GL_RGB and GL_RGBA format textures, you must set a device-dependent command-line argument when invoking the X server:

! PowerStorm 300/350 Server args start
       -pn -bs -su -nice -2 -I -riDefaultTexel32
! PowerStorm 300/350 Server args end

The portable way to read the contents of OpenGL buffers is to use the glReadPixels call. However, if using XGetImage to serve this purpose is desirable, we have provided an option which will return the expected results, even for inferior or overlapping double-buffered OpenGL windows. The performance of XGetImage calls will be negatively impacted with this option enabled, so it should only be turned on if necessary.

To enable the double-buffer-aware XGetImage, you must set a device-dependent command-line argument when invoking the X server:

! PowerStorm 300/350 Server args start
       -pn -bs -su -nice -2 -I -riDBAwareGetImage
! PowerStorm 300/350 Server args end

However, it should be noted that the performance of these thread-safe libraries may be significantly reduced. In most cases, the overhead of locking down contexts clearly outweighs the benefits of rendering from multiple threads. For example, the Viewperf benchmarks show a 3x to 5x performance degradation.

To enable the thread-safe OpenGL client libraries, you simply need to add a directory to your LD_LIBRARY_PATH environment variable before running your application. For example, assuming a csh-compatible shell:

setenv LD_LIBRARY_PATH /usr/opt/3X0/threadsafe

setenv LD_LIBRARY_PATH /usr/opt/3X0/threadsafe:${LD_LIBRARY_PATH}

Users running only 2D applications may prefer to enable backing store and save under, as these features may improve performance in some cases. To do this, you need to edit the server configuration file /usr/var/X11/Xserver.conf to remove the options currently disabling these features. Search for the following lines in this file:

! PowerStorm 300/350 Server args start
       -pn -su -bs -nice -2
! PowerStorm 300/350 Server args end

! PowerStorm 300/350 Server args start
       -pn -nice -2
! PowerStorm 300/350 Server args end

/usr/sbin/init.d/xlogin restart

1.10.2 OpenGL Restrictions

The PowerStorm 350 does not have such an architecture. When glDrawBuffer() is set to GL_FRONT, GL_BACK, or GL_FRONT_AND_BACK, and the application is rendering to a stereo visual, the geometry must be sent through the OpenGL pipeline twice, sequentially. This leads to a performance reduction which happens to be significantly worse than having the application draw the same geometry twice (once to GL_LEFT and once to GL_RIGHT).

For this reason, it is important that you choose a mono visual when rendering the same view to both left and right buffers. If an application needs to alternate between rendering mono and stereo images, it can be written to switch between mono and stereo visuals rather than always using a stereo visual.

The A- and B-chips accommodate 8-bit channels for red, green, and blue. The remaining 8-bit channel is used for 8-bit overlay planes instead of a destination alpha channel. Most blending techniques only use the source alpha channel and do not require a destination alpha channel.

By default, OpenGL software for PowerStorm 300/350 forces a direct-rendered OpenGL rendering context whenever the connection is "direct," for example, when DISPLAY is :0. If necessary, this behavior can be overridden by defining the following environment variable:

setenv ALLOWINDIRECT

1.10.2.6 GLX Pixmap Support

To do this, you need to edit the server configuration file /usr/var/X11/Xserver.conf to add the option for enabling the software renderer. Search for the following lines in this file:

! PowerStorm 300/350 Server args start
       -pn -su -bs -nice -2
! PowerStorm 300/350 Server args end

! PowerStorm 300/350 Server args start
       -pn -su -bs -nice -2 -I -riGLXuseSWindirect
! PowerStorm 300/350 Server args end

/usr/sbin/init.d/xlogin restart