Starbase Functionality

Plotter Input

Each HP-GL plotter can be considered a locator device in digitizer mode. Three values are located: X, Y, and Z. The X and Y values specify an absolute Cartesian location on the plotter's scaled plotting area in Virtual Device Coordinates. The Z value equals the maximum Virtual Device Coordinate if the pen is down, and the minimum Virtual Device Coordinate if the pen is up.

When in digitizer mode, the plotter displays its "enter" indicator. The Enter button is used to trigger either an event or request.

Sample calls will not cause the plotter to display its enter indicator.




	NOTE: Not all plotters are capable of indicating an enter condition. Consult your plotter manual for further information.

Pen Selection

The following set of rules are used to select the pen the plotter will actually use.

If the program specifies a pen number that is zero, the plotter does a PEN UP.

If the program specifies a pen number that is less than or equal to the number of pens the device driver recognizes, that pen number is sent to the plotter. If the plotter has a pen with that number, it is used. If the plotter does not have a physical pen with that number, a device-dependent action will occur. Either the plotter will use the pen with the largest number, or a MOD calculation is made and the resulting pen number is used.

If the program specifies a pen number that is larger than the number of pens the device driver recognizes, the device driver does a MOD calculation to define the pen number to send to the plotter. If the MOD calculation returns a non-zero value, the driver sends that calculated pen number to the plotter. If the MOD calculation returns a zero value the device driver makes an exception from sending pen number 0, and sends the largest pen number.

Exceptions to Standard Starbase Support

Commands Not Supported (no-ops)

The following commands are not supported. If one of these commands is used, it is ignored.

 alpha_transparency                   display_enable
 await_retrace                        double_buffer
 backface_control                     drawing_mode
 background_color                     file_to_bitmap
 background_color_index               file_to_dcbitmap
 bank_switch                          file_to_intbitmap
 bf_alpha_transparency                fill_dither
 bf_control                           hidden_surface
 bf_fill_color                        intbitmap_print
 bf_interior_style                    intbitmap_to_file
 bf_perimeter_color                   intblock_move
 bf_perimeter_repeat_length           intblock_read
 bf_perimeter_type                    intblock_write
 bf_surface_coefficients               interior_style (INT_ OUTLINE) 
 bf_surface_model                     interior_style (INT_POINT)
 bf_texture_index                     intline_width
 bitmap_print                         light_ambient
 bitmap_to_file                       light_attenuation
 block_move                           light_model
 block_read                           light_source
 block_write                          light_switch
 clear_control                        line_endpoint
 contour_enable                       line_filter
 dbuffer_switch                       pattern_define
 dcbitmap_print                       perimeter_filter
 dcbitmap_to_file                     set_capping_planes
 dcblock_move                         set_model_clip_indicator
 dcblock_read                         set_model_clip_volume
 dcblock_write                        shade_mode
 define_contour_table                 shade_range
 define_raster_echo                   surface_coefficients
 define_texture                       surface_model
 define_trimming_curve                texture_index
 deformation_mode                     texture_viewport
 depth_cue                            texture_window
 depth_cue_color                      viewpoint
 depth_cue_range                      write_enable
 depth_cue-range                       zbuffer_switch

Commands Conditionally Supported

The following commands are supported under the listed conditions:

clear_view_ surface

New page on devices with automatic paper feeders.^[35]

define_ color_table

Updates software color table only (an operator must physically change the pens).

hatch_spacing

Care should be taken to specify spacings greater than or equal to one pen width.

interior_ style

Only the INT_SOLID, INT_HATCH, and INT_HOLLOW styles are supported.

text_ precision

Only STROKE_TEXT precision is supported.

vertex_format

The "use" parameter must be zero, any extra coordinates supplied will be ignored.

with_data

The following routines are called with_data routines because they contain with_data in their routine names. These with_data routines are supported by the HP-GL graphics devices.

partial_polygon_with_data3d
polygon_with_data3d
polyhedron_with_data
polyline_with_data3d
polymarker_with_data3d
quadrilateral_mesh_with_data
triangle_strip_with_data

For detailed information on these routines, read the Starbase Reference. In some cases, you will be able to find the routines under their own name, but in other cases, you will need to use the first part of the routine name to locate these routines (e.g., polyline_with_data3d is described on the man page for polyline(3G)).

^[35] Some plotters will only eject the paper if it has been plotted on.

Starbase Functionality

Technical documentation

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Plotter Input

Pen Selection

Exceptions to Standard Starbase Support

Commands Not Supported (no-ops)

Commands Conditionally Supported