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software:vectors [2016/06/12 09:48] ex_writer [Limit Table] |
software:vectors [2016/06/12 09:55] (current) ex_writer [X/Y Check Mask (VBXCHK, VBYCHK)] |
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| ==== X/Y Check Mask (VBXCHK, VBYCHK) ==== | ==== X/Y Check Mask (VBXCHK, VBYCHK) ==== | ||
| - | The check mask byte determines whether a limit (i.e., boundary) is attained and how to respond. The limit value is set in vector write routine (e.g., [[system routines:screen handler#vect|VECT]]). | + | The check mask byte determines whether a limit (i.e., boundary) is attained and how to respond. Limit values are defined in the object's [[#limit table]] and passed to the object vectoring routines (i.e., [[system routines:screen handler#VECT]] or [[system routines:screen handler#VECTC]]). |
| {{:checks_mask.png}} | {{:checks_mask.png}} | ||
| ^ Bit ^ Name ^ Label ^ Description ^ | ^ Bit ^ Name ^ Label ^ Description ^ | ||
| - | | 0 | Limit Check | | Set to one (1) to enable limit checking. | | + | | 0 | Limit Check | VBCLMT | Set to one (1) to enable limit checking. | |
| - | | 1 | Reverse Delta | | Changes the sign of the delta when the limit is reached. This can be used to cause objects to 'bounce' off barriers. | | + | | 1 | Reverse Delta | VBCREV | Changes the sign of the delta when the limit is reached. This can be used to cause objects to 'bounce' off barriers. | |
| - | | 3 | Limit Attained | | In contrast to the bounce effect, the system will set the limit attained flag and hold the pattern at the limit position until the user changes the delta. | | + | | 3 | Limit Attained | VBCLAT | In contrast to the bounce effect, the system will set the limit attained flag and hold the pattern at the limit position until the user changes the delta. | |
