Device Descriptions

HCRX-8

The HCRX-8 graphics device has two hardware color maps in the image planes and two hardware color maps in the overlay planes. It supports color recovery, as explained in the section "HP Color Recovery" in this chapter.

This display has 1280x1024 pixels with two banks of eight image planes and eight overlay planes. There is no offscreen memory in the frame buffer.

The HCRX-8 device supports 8 planes single-buffered or 8/8 double-buffered.

The only X server mode supported is combined mode with eight planes, double-buffered. For information on supported X server modes, read the section "Supported X Server Modes" in Chapter 1 “Introduction and Device Comparison”.

The PowerShade software adds support for lighting, shading and Z-buffering.

The HCRX-8 device supports all Starbase color map modes (CMAP_NORMAL, CMAP_MONOTONIC, and CMAP_FULL).

There are two hardware color maps available for use with the image planes. At most, one of the two color maps will be dedicated for use by direct color graphics windows. The other one will be shared by all indexed color graphics processes.

In addition to the two hardware color maps in the image planes, there are two hardware color maps in the overlay planes. One of the hardware color maps has the default X11 color map permanently installed in it. This is done to avoid technicoloring your X11 and HP VUE backgrounds.

HCRX-8Z

This device description is a superset of the HCRX-8 graphics device's description.

The HCRX-8Z graphics device includes an optional accelerator that attaches to the HCRX-8 device to provide high performance 3D solids modeling and high performance 3D wireframe. The HCRX-8Z accelerator has a dedicated 24-bit Z-buffer. The hphcrx driver automatically uses the HCRX-8Z accelerator if it is present. The primary use of the HCRX-8Z accelerator is for 3D solids modeling, including drawing Starbase polygons, rectangles, triangle strips, quadrilateral meshes, and spline surfaces.

The HCRX-8Z graphics device has a high-speed scan converter that accelerates rendering into the frame buffer. The HCRX-8Z device supports all Starbase color map modes (CMAP_NORMAL, CMAP_MONOTONIC, and CMAP_FULL).

HCRX-24

The HCRX-24 graphics device has two hardware color maps in the image planes and two hardware color maps in the overlay planes. It supports HP Color Recovery in all 8 plane visuals, as explained in the section "HP Color Recovery" in this chapter.

The HCRX-24 graphics device has 24 image planes and 8 overlay planes. The screen resolution is 1280x1024 pixels. There is no offscreen memory in the frame buffer.

You can render to the image planes in three ways:

8-bit indexed color (CMAP_NORMAL, CMAP_MONOTONIC, CMAP_FULL)
12-bit direct color (CMAP_FULL)
24-bit direct color (CMAP_FULL)

You can select each of the three rendering modes on a per-window basis. The mode selected is a function of the depth of the window created and double-buffer mode.

In 8-bit indexed mode, each pixel is used as an index into a 256-entry color map. Each entry in the color map provides eight bits per color for each of the red, green and blue components, providing a color palette of over 16 million colors. Double-buffering is achieved by switching between two banks of 8-bit indexes. You can perform 3:3:2 direct color emulation in this mode.

The PowerShade software adds support for lighting, shading and Z-buffering.

In 12-bit direct color mode, each pixel is represented by four bits per color channel to allow for double-buffering. One buffer resides in the upper 4-bits and the other buffer resides in the lower 4-bits of each color channel. Dithering improves the color resolution.

In 24-bit direct color mode, a pixel is represented by eight bits each for red, green, and blue. Double-buffering is not supported in this mode.

In addition to the two hardware color maps in image planes, there are two hardware color maps in overlay planes. One of the hardware color maps has the default X11 color map permanently installed in it. This is done to avoid technicoloring your X11 and HP VUE backgrounds.

The X server works only in combined mode. For information on supported X server modes, read the section "Supported X Server Modes" in Chapter 1 “Introduction and Device Comparison”.

HCRX-24Z

This device description is a superset of the HCRX-24 graphics device's description.

The HCRX-24Z includes an optional accelerator that attaches to the HCRX-24 device to provide high performance 3D solids modeling and high performance 3D wireframe with anti-aliasing. The HCRX-24Z accelerator has a dedicated 24-bit Z-buffer. The hphcrx driver automatically uses the HCRX-24Z accelerator if it is present. The primary use of the HCRX-24Z accelerator is for 3D solids modeling, including drawing Starbase polygons, rectangles, triangle strips, quadrilateral meshes, and spline surfaces.

The HCRX-24Z device has a high-speed scan converter that accelerates rendering into the frame buffer. The HCRX-24Z accelerator can render to the image planes on the HCRX-24 in 8-bit, 12-bit, and 24-bit mode.

Overlay Plane Rendering

The hpvmx or the sox11 device driver is used for Starbase rendering to the overlay planes. For more information on Starbase rendering to the overlay planes, read the chapters "HP VMX Device Driver" and "The Starbase-on-X11 Device Driver" in this manual.

For comments about how the hpvmx driver is supported in the image planes of the HCRX family of graphics devices, see below. 8/8 VM double-buffering is also supported in the overlay planes using the hpvmx driver.

If an overlay plane window is gopened with a driver name of NULL, the hpvmx driver will be used. See the table, "Driver Selection at gopen" in the chapter "HP VMX Device Driver" in this manual for details.

PowerShade, 3D Surfaces Software

PowerShade is an optional software package that supports lighting and shading in graphics applications. It has capabilities for both surface rendering and volumetric rendering, the latter on the HCRX-24 and HCRX-24Z only.

The HCRX-8Z and HCRX-24Z automatically support PowerShade capabilities. But, in order to use the HP VMX driver with PowerShade on these devices, you must install the PowerShade software. For more information on HP VMX, read the chapter "HP VMX Device Driver" in this manual.

HP Color Recovery

The HCRX family of graphics devices use HP Color Recovery for shaded fill areas in 8 plane visuals (for example, polygons, spline surfaces, etc.). Color recovery will generate a better picture by attempting to eliminate the graininess caused by dithering. HP Color Recovery is available on all windows on the HCRX-8 and HCRX-8Z, but only in 8-bit windows on the HCRX-24 and HCRX-24Z.

There are two components to HP Color Recovery. A different dither cell size (16×2) is used when rendering shaded polygons, and a digital filter is used when displaying the contents of the frame buffer to the screen.

HP Color Recovery is available on the HCRX family of graphics devices whenever you are in CMAP_FULL mode and you have used the INIT flag in the gopen, shade_mode, or the double_buffer function to initialize color maps. Keep in mind that the default color map mode is CMAP_NORMAL for PseudoColor visuals; therefore, the HP Color Recovery color map will not be set up until you call shade_mode to set the mode to CMAP_FULL and use INIT.

HP Color Recovery is available when using either PseudoColor or TrueColor visuals.

Under some conditions HP Color Recovery can produce undesirable artifacts in the image. This can also happen with 4×4 dithering, but the artifacts are different. However, images rendered with HP Color Recovery are seldom worse than what dithering produces, and in most cases, HP Color Recovery produces significantly better pictures than dithering. Note that 4×4 dithering, like HP Color Recovery, is available in the CMAP_FULL color map mode, but not in the CMAP_NORMAL color map mode.

HP Color Recovery is available by default. If you wish to disable HP Color Recovery, you can do it in one of three ways:

You can export the environment variable HP_DISABLE_COLOR_RECOVERY before starting up the X server (see the section "Accessing HP Color Recovery with X Windows" in this chapter). Setting this environment variable prior to starting up the X server disables HP Color Recovery for all applications and any attempts to enable HP Color Recovery will be ignored. Remember, if you set this environment variable prior to starting up the X server, you cannot re-enable HP Color Recovery from the command line or from within an application. To set this environment variable before HP VUE starts up the X server, place the following line in your 〈vue-config〉^[6]/Xconfig file:
Vuelogin*environment: HP_DISABLE_COLOR_RECOVERY=TRUE
and restart HP VUE.
If you are using X windows (starting the X11 server with the x11start command) instead of HP VUE, place the following line in your .x11start file (assuming you are using the Korn shell):
export HP_DISABLE_COLOR_RECOVERY=TRUE
You can export the environment variable HP_DISABLE_COLOR_RECOVERY before running your application. Setting this environment variable to any value disables color recovery for subsequently executed applications. To set this environment variable in your current X11 window, execute this command on the command line before run your application (assuming you are using the Korn shell):
export HP_DISABLE_COLOR_RECOVERY=TRUE
You can disable HP Color Recovery programmatically by using the Starbase gescape COLOR_RECOVERY_CONTROL. For details on this gescape, read the subsequent section "Gescapes."

In CMAP_FULL shade mode, disabling HP Color Recovery will result in normal dithering of shaded fill areas. Note that HP Color Recovery is not available in any other shade mode.

HP Color Recovery is enabled in conjunction with a particular X color map that is associated with your window. If that X color map is not currently installed in hardware by your window manager, you will not see the effect of the color recovery filter.

The HP Color Recovery color map is a READ-ONLY color map. Any attempts to change it will be ignored and no error will be reported.

Gescapes

The COLOR_RECOVERY_CONTROL gescape can be used to disable HP Color Recovery. Passing it a 0 value in arg1 will disable HP Color Recovery, a 1 value will enable it (HP Color Recovery is enabled by default). The arg2 parameter is ignored. The effect of this gescape will not take place until the next time you call shade_mode or double_buffer with the INIT flag. For example:

gescapearg  arg1;
 
/* Disable HP Color Recovery */
arg1.i0 = 0;
gescape(fildes, COLORRECOVERYCONTROL, &arg1, NULL);
shademode(fildes, CMAPFULLINIT,0);

^[6]The actual path names of directories in angle brackets depend on the file system structure. See the Graphics Administration Guide for details.