DO(OPCS) Optical Printer Control System DO(OPCS) NAME do - repeat commands USAGE do [count] [commands] do until (expr) [commands] EXAMPLES do 12 rep 15 pro -5 ^These commands repeat 12 times from left to right. do until (cam>=45) rep 15 pro -5 ^Loop until camera counter reaches 45 or greater. DESCRIPTION Repeat commands. Commands that follow the DO command up to the end of line are repeatedly executed the number of times specified by [count]. If 'DO UNTIL (expr)' is used, looping continues until (expr) is true. DO commands can be nested within a line. That is to say, 2 DO commands can appear on the same line: do 4 seek 10 do 8 rep 1 pro -1 | | | These loop 32 times; the 'DO 4' loop | executes the 'DO 8' loop 4 times. | These loop 4 times In the case of do until (expr), usually (expr) is a conditional expression that compares one of the counters to a value, eg: do until (cam=12) .. # until cam counter is 12 do until (cam>=12) .. # until cam counter greater than or equal to 12 do until (pro>200) .. # until main projector counter greater than 200 EXAMPLES Run three 5 frame cycles of a moving projector image: rat 1 1 do 3 rep 5 pro -5 ^ These repeat 3 times from left to right. Run twelve 4-frame cross dissolves on every 8th projector image, effectively 'weaving' still frames from an otherwise slow-motion moving projector image: do 12 dxo 4 cam 4 cam -4 pro 8 dxi 4 cam 4 ^ These repeat 12 times Run a script file 7 times: do 7 run smallfile.run ^ This script is executed 7 times Shoot a 12x wedge, allowing camera operator to manually load ND filters into the projector's filter holder for each frame: do 12 pse cam 1 ORIGIN Gregory Ercolano, Los Feliz California 12/16/89