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Tracking Symbol and Frame Buffer Nonswitch Mode
Dials Feature
Pick Control Tablet Interactions
If the frame buffer nonswitch mode option is specified on a GBGOP order and there is a reason (or cause) to track the stylus or cursor on the tablet, the destructive tracking symbol could ultimately destroy the image on the screen.
However, the nondestructive tracking symbol option allows symbol tracking, even in this case, without harming the image°"
The processor dials feature provides eight cone-shaped dials, each of which may be turned continuously in either direction. Upon rotating the dials, a range of scalar values indicating direction and extent of rotation (since last reset) are input to the processor. A display program can read and interpret these scalar values for any suitable purpose, such as translating, scaling, and rotating two- or
three-dimensional images when the Transformation and Clipping Feature (TCP) is installed. The dial values are read by issuing a GSDEVI order addressing device number 2. (See "GSDEVI-Store Device Input" on page 5-45 for details.)
Each dial has a possible 256 increments (interrupts/revolution) in the 360 degrees the dial can be turned. The dials feature supports seven interrupt settings that can be specified by using the setup option (see IBM 5080 Graphics System:
Operation and Problem Determination, GA23-0133, for details). The specifiable interrupts are 4, 8, 16, 32, 64, 128, and 256 possible points.
Because each dial is a high-resolution potentiometer, an electrically inactive area (dead zone) of approximately 1/16th (20 degrees) of the total potentiometer area exists. Thus, only 242 (00-240 and 248) interrupt values out of a total
granularity of 256 are ever transmitted. The value 248 is transmitted only on interrupt settings greater than 16. Accordingly, only 62, 122, and 242 points are transmitted for interrupt settings of 64, 128, and 256, respectively.
A pick module that compares the coordinates of the pickable primitives (for example, lines, markers, and characters) performs a correlation with a pick window established around an X-Y point in virtual image space.
The pick window can be set directly from the tablet in the following manner:
From the tablet X-Y value. This value may be updated periodically during the processing of a display program, provided there has been no GSYMB order since the last GBGOP or GSRT order.
• From a GSYMB order. If the d bit of the GSYMB order is set to 1, the pick window defined in the GSYMB order overrides any previous settings and prevents further dynamic updating from the tablet. If the d bit is set to zero, GSYMB does not have any effect on the setting of the pick window.
Note: The GSYMB order is a 3250-compatible order. When a GSYMB order is encountered in display storage, the tablet system pick device mode (if active) is negated. Picking is now done based on the current draw position when the
GSYMB order was issued. Tablet system pick device mode will be reinstated upon execution of the next Set Buffer Address Register and Start Command or Start Display Program structured field.
Pick Detection Modes and Indicators
Two modes and four indicators per processor interact to define the pick detect environment at any instant during display program execution. These modes and indicators are defined below along with brief descriptions of their use. Precise definitions of their interactions and relation to the use of the stylus, stylus switch, and execution of the graphic orders are detailed in a set of decision tables. In addition, a less formal description of each graphic order is given, and the action of each order is defined with reference to the modes and indicators.
The two pick modes determine whether a pick detect is allowed, and, if it is allowed, what the reaction to the detect will be. A pick detect occurs when the modes are set appropriately, and displayed data of adequate intensity (color or grayshade) is seen by the pick module. [If the Load Attribute Register ( GLA TR) order is used, adequate intensity is assumed; if the 3250-compatible Load
Attribute Register (GLAR) order is used, intensity must be set appropriately.] See
"Interaction with Pick Indicators" on page 3-24 for a definition of the conditions required for a pick detect. See Appendix C for the status and sense data for an interrupt resulting from a pick detect.
The pick modes are pick detect mode and pick interrupt mode.
Pick Detect Mode: Possible states are switch enabled (S), nonswitch enabled (N), and disabled (D).
No pick detects can occur during the disabled (D) state.
One pick detect interrupt can occur per stylus switch closure during the switch enabled (S) state.
Multiple pick detects can occur in a display program execution cycle during the nonswitch enabled (N) state; these are independent of the use of the stylus switch.
(Both nonswitch enabled and switch enabled detects can occur in the same execution cycle.)
Pick Interrupt Mode: Possible states are deferred (d) and immediate (i).
In the deferred state, if a pick detect occurs, an indicator (the pick indicator, or PI) is set in the processor and display program execution continues normally (the detect is "remembered").
In the immediate state, if a pick detect occurs, display program execution ceases immediately and an I/ 0 interrupt is sent to the host CPU.
The two modes, pick detect and pick interrupt, areindependent of each other, thus giving six possible combined states: Sd, Nd, Dd, Si, Ni, and Di.
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Pick Indicator (PI)
The four indicators are:
Abbreviation PI PBI SDI TSI
Name
Pick indicator
Permit branch indicator Single detect indicator Tip switch indicator
Each of the four indicators has two possible states: on (1) and off (0). The descriptions below list the means of setting each indicator on or off as well as the functions whose action is modified by the state of the indicator.
Note: The setting and resetting of the PI and TSI may affect the condition code (see "Condition Code Register" on page 3-7 for details).
The pick indicator (PI) is in attribute register 13.
The PI is set on by:
• The pick module detecting the intersection of a line, character, pixel array, area fill, circle, or marker independent of the color
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grayshade with the pick window (previously set by the pick device, that is, the tablet or a GSYMB order). When the pick detect mode is in either the switch enabled or nonswitch enabled state, the pick interrupt mode is in the def erred state.Note: This comparison is independent of the frame buffer mask, frame buffer function, pixel array, and area fill pattern values.
A Load Attribute Register (GLATR) order (to attribute register 13).
The PI is set off by:
Execution of a GBGOP or GSRT order.
Execution of a Branch on Deferred Detect (GBDD) or Branch on No-Detect (GBND) order.
Receipt by the processor of a Set Buffer Address Register and Start command or Write Structured command containing a Start Display Program structured field.
• A Begin Segment (GBGSEG) order.
A GLATR order (addressing attribute register 13).
The PI is used to determine the action of the following orders:
• Branch on No Detect (GBND)
• Branch on Deferred Detect (GBDD) Permit Detect Interrupt (GPDI) Branch on Condition ( GBC)
Permit Branch Indicator (PBI)
Single Detect Indicator (SDI)
The permit branch indicator (P BI) is in attribute register 13 and indicates a closed switch state with no pick.
The PBI is set on by:
Execution of a GBGOP or GSR T order when the stylus switch is closed.
• Execution of a GSDEVI order when the unit's switch is closed or the function keys of the unit are pressed.
• Receipt of a Set Buffer Address Register and Start command or Write Structured command containing a Start Display Program structured field when the stylus switch is closed.
A GLATR order (addressing attribute register 13).
The PBI is set off by:
A pick detect when the pick detect mode is in the switch enabled state.
• Execution of a GBGOP or GSR T order when all stylus switches are open.
• Receipt of a Set Buffer Address Register and Start command or Write Structured command containing a Start Display Program structured field when all stylus switches are open.
Execution of a GBND order when the pick detect mode is in the switch enabled state.
A GLATR order (addressing attribute register 13).
The PBI is used to determine the action of:
Branch on No Detect (GBND) order.
The single detect indicator (SDI) is in attribute register 13 and is used to prevent multiple picking during the time the switch is closed.
The SDI is set on by:
• A pick detect when the pick detect mode is in the switch enabled state.
• A GSDEVI order interrupt from a closed unit switch or a pressed program function key.
• A GLATR order (addressing attribute register 13).
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Tip Switch Indicator (TSI)
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The SDI is set off by:
• Execution of a GBGOP or GSRT order when all stylus switches are open.
Receipt of a Set Buffer Address Register and Start command or Write Structured command containing a Start Display Program structured field when the pick stylus switch is open.
• Receipt of a Set Buffer Address Register and Start command or Write Structured command containing a Start Display Program structured field when the processor has an outstanding pick interrupt or a GSDEVI order interrupt.
• Any processor reset.
A GLATR order (addressing attribute register 13).
The SDI is used to determine the action of:
• A pick detect when the pick detect mode is in the switch enabled state.
A GSDEVI order interrupt.
The tip switch indicator (TS!) is in attribute register 13 and indicates the state of the tablet stylus switch.
The TSI is set on by:
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closed or one or more of the tablet function keys is pressed.
• Receipt of a Set Buffer Address Register and Start command or Write Structured command containing a Start Display Program structured field when one or more stylus switches is closed or one or more of the tablet function keys is pressed.
A GSDEVI order with t= 1 if the referenced unit switch is closed or one or more function keys of the referenced unit is pressed (at the previous GBGOP or GSRT order).
• A GLATR order (addressing attribute register 13).
The TSI is set off by:
• Execution of a GBGOP or GSR T order when the pick stylus switch is open.
• Receipt of a Set Buffer Address Register and Start command or Write Structured command containing a Start Display Program structured field when the stylus switch is open.
• A GSDEVI order with t= 1 if the referenced unit switch was open and no function key was pressed (at the previous GBGOP or GSRT order).
• A GLATR order (addressing attribute register 13).
The TSI is used to determine the action of:
• A Branch on Switch Open (GBSO) order.
• A Branch on Condition (GBC) order.
• A pick detect when the pick detect mode is in the switch enabled state.
Interaction with Pick Indicators
This section defines those functions that interact with the settings of the pick indicators. The definitions are presented in the form of decision tables. The actions indicated by an X in the tables are taken only if all tests in the same column are satisfied. A test without a YES or NO indicated is always satisfied.
Within a table the columns are mutually exclusive (that is, one set of tests cannot satisfy two columns). However, the set of columns does not always include all possible combinations of the tests. Any combinations not shown result in no action (that is, no-operation).
1. The Begin Order Processing (GBGOP) and Start Regeneration Timer (GSRT) orders test:
Is stylus switch
closed? YES NO*
Actions:
Set PI off
x x
Set PBI on
x
Set PBI off
x
Set SDI off
x
Set state to Si
x x
Set TSI on
x
Set TSI off
x
* SDI and PBI are set off only if all stylus
switches are open and no function key is pressed.
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2. The Set Buffer Address Register and Start command and Start Display Program structured field test:
Is tip switch closed? YES YES NO* NO*
Is an enable switch detect interrupt
pending? YES NO YES NO
Actions:
Set PI off
x x x x
Set PBI on
x x
Set PBI off
x x
Set SDI off
x x x
Set state to Si
x x x x
Set TSI on
x x
Set TSI off
x x
*
SDI and PBI are set off only if all stylusswitches are open and no function key is pressed.
3. The Branch on Deferred Detect (GBDD) order tests:
Is PI on? YES NO
Actions:
Branch to target
address
x
Set PI off
x
4. The Branch on No-Detect (GBND) order tests:
Is state
=
Si or Sd? YES YES NO NO Is state = Ni or Nd? NO NO YES YESIs PBI on? YES
Is PI on? NO YES NO YES
Actions:
Branch to target
address
x x
Set PBI off
x x
Set PI off
x x
NO NO
x
5. The Permit Detect Interrupt (GPDI) order tests:
Is PI on? YES NO
Actions:
Interrupt
x
Set pick detect mode from deferred to imtriediate (i)
state
x
6. The Branch on Switch Open (GBSO) order tests:
Is TSI on? YES NO
Actions:
Branch to target
address NO YES
7. The Store Device Input (GSDEVI) order tests:
Is I= 1? NO YES
Is tip switch closed? or
Is any PF key pressed? YES
Is SDI off? YES
Actions:
Interrupt
x
Set SDI on
x
8. System action when a pick detect occurs:
Adequate color
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grayshade for pick
device? (see Note) YES YES YES
Is state= Si? NO
Is state = Sd? NO YES
Is state= Ni? NO YES
Is state= Nd? NO YES
Is SDI off? YES
Is TSI on? YES
Actions:
Interrupt
x
Set PI on
x x
Set PBI off
x
Set SDI on
x
Note: Test applies only if 3250-compatible GLAR order used.
YES YES
x x x
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Coordinate System Specification
Virtual Image Space
The processor supports a world coordinate system extending from ±32K (-32768 to +32767) for X,Y, and Z coordinates. The visible region of the coordinate space is called the virtual image space. (See Figure 3-2.)
Coordinates existing completely outside the virtual image space should be specified only if the Transformation and Clipping Feature (TCF) is installed and active; otherwise, the results are unpredictable. Lines beginning in the virtual image space, or passing through it, may wrap. (For an explanation of the uses of world coordinate space, refer to the description of the TCF on page 3-37.)
There are 4096 addressable points in each of the X (horizontal) and Y (vertical) dimensions of the virtual image space; the bottom left point is 0,0 and the top right point is 4095 ,4095. The viewable area is the 4096 x 4096 space, which is mapped by the raster generator into "screen space" (1024 x 1024) by truncating the 2 low-order bits.
Coordinate Addressing for Lines and Markers
· Any point in the world coordinate space may be addressed by graphic orders in the display program.
The coordinates contained in a graphic data list may be absolute, incremental, or relative, depending on the graphic order that precedes the list.
•
Absolute Coordinates: When a graphic order specifies absolute coordinates, X-Y (and Z) values from the data list replace the current value in the X-Y-Z position registers. Thus, a move or draw occurs from the previous current draw position to the new position, or a marker is plotted at the new position in the same way.
Incremental or Relative Coordinates: When a graphic order specifies
incremental or relative coordinates, X-Y (and Z) values from the data list are added to the current value in the X-Y-Z position registers, creating a new current draw position. Thus, a move or draw occurs from the previous current draw position incremented by the value in the data list, or a marker is plotted at the new position in the same way.
Coordinates outside the virtual image space are usually not specified as absolute coordinates unless coordinate values are specified using a 16-bit signed binary number. However, 12-bit absolute, incremental, and relative coordinates could produce requests to place the current draw position outside the image area. The display of markers and lines is inhibited outside this area. In particular, a line having some part outside the virtual image space has that part inside the area displayed correctly up to the edge of the area.
Note: This "clipping" of lines at the virtual image space boundary is not compatible with the 3250, which would blank the entire vector.
The processor maintains logically correct X-Y-Z values within the limits -32768 and +32767 even if several consecutive movements remain outside the virtual image space. Attempts to increment these coordinates outside these limits causes an undefined current draw position.
(+32767,+32767)
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(-32768,-32768)
Not Displayable
Displayable
(4095,4095)
(0,0)
Virtual Image Space (Visible Region)
World Coordinate Space
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Figure 3-2. Base 5080 Coordinate Space
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IThe host system may determine the contents of the X-Y-Z position registers by issuing a Sense channel command in response to a pick detect or at any other time. (See "X-Y-Z Position Registers" on page 3-6.) The GSDEVI order optionally returns coordinate values in the range of -32768 to +32767 to the display program.
The X and Y coordinate values returned to the host system by the
3250-compatible Read X-Y Position Register command, or stored in the display storage by the Store X-Y Position Registers (GSXY) order, are modulo 4096. The processor drops the Z coordinate value and sets the 4 high-order bits of the X and Y coordinates to zero in processing these functions. In this case, it is not possible to determine from the contents of the X-Y position values whether the current draw position is outside the virtual image space and, hence, outside the
displayable area.