by Bill Russell
This project illustrates how simple concepts build on top of each other to build something useful, such as a clock. It also illustrates simple animation and a range of various commands, including using Logo to interact with system resources such as the built-in clock.
TO SECHAND :ERASE :ANGLE ; -- ; Set the angle for the hand and erase if TRUE, otherwise ; draw the second hand at the specified angle. ; -- SETHEADING :ANGLE SETPC "DARKRED IF :ERASE THEN SETPC "WHITE SETWIDTH 3 PD FD 120 BK 120 END TO RUNCLOCK ; -- ; Initialize clock variables, draw the clock, and update it every ; second. If the user presses "Q" then quit. ; -- ; Initialize vars MAKE "LASTTIME TIME MAKE "HOURANGLE 0 MAKE "MINANGLE 0 MAKE "SECANGLE 0 ; Draw clock without hands & instruct the user how to quit CLEARTEXT CLOCKFACE CLOCKNUMBERS HIDETURTLE PRINT "|To quit the Ticking Clock, press 'Q'...| ; *** Main loop *** LABEL "CLOCKTICK ; See if the user wants to quit MAKE "NEXTKEY KEY IF NEXTKEY < 0 THEN GO "SKIPQUITCHECK IF (CHAR NEXTKEY) = "Q THEN GO "QUITNOW IF (CHAR NEXTKEY) = "|q| THEN GO "QUITNOW ; Update clock if a second has passed LABEL "SKIPQUITCHECK MAKE "NEWTIME TIME IF (NEWTIME <> LASTTIME) THEN CLOCK IF (NEWTIME <> LASTTIME) THEN MAKE "LASTTIME TIME WAIT 50 GO "CLOCKTICK ; *** End of Main Loop *** LABEL "QUITNOW PRINT "|Thanks for stopping bye!| END TO CLOCK ; -- ; Draw the hands of the clock in the correct location ; based on the current hour, minute, and second of the ; system time. ; -- ; Erase all the old hands first BIGHAND TRUE MINANGLE ; erase old hand SECHAND TRUE SECANGLE SMALLHAND TRUE HOURANGLE ; Update angles for each hand MAKE "MINANGLE (360 / 60) * (ITEM 2 TIME) MAKE "HOURANGLE (360 / 12) * ((REMAINDER FIRST TIME 12) + ((ITEM 2 TIME) / 60)) MAKE "SECANGLE (360 / 60) * (ITEM 3 TIME) ; Draw each hand at the calculated angle BIGHAND FALSE MINANGLE ; Draw hour hand 1st in case small hand overlaps SMALLHAND FALSE HOURANGLE ; Draw minute hand next SECHAND FALSE SECANGLE ; Draw second hand last ; Make a clock tick sound PLAY [V50 I37 O4 64E] END TO CLOCKFACE ; -- ; Draw the circle and minute/hour markers ; -- DRAW SETWIDTH 10 STAMPOVAL 180 180 SETWIDTH 5 REPEAT 60 [PU FD 180 PD BK 10 PU BK 170 RT 360 / 60] SETWIDTH 10 REPEAT 12 [PU FD 180 PD BK 20 PU BK 180 - 20 RT 360 / 12] END TO SMALLHAND :ERASE :ANGLE ; -- ; Draw the hour hand (small hand), and erase if TRUE. ; -- SETHEADING :ANGLE SETPC "DARKGREEN IF :ERASE THEN SETPC "WHITE SETWIDTH 10 PD FD 75 FOR "W 10 1 [SETWIDTH :W FD 2] PU BK 95 END TO CLOCKNUMBERS ; -- ; Evenly space the numbers 1 thru 12 around the clock face ; -- PU HOME FOR "CLOCKNUM 1 12 [PU RT (360 / 12) FD 140 CENTERTT :CLOCKNUM PU BK 140] END TO CENTERTT :MSG ; -- ; For Arial Baltic, the ratio of the font ; is 2:1 for height:width. Then 50% more ; must be added to account for the spacing ; added around each letter. This is does ; not work for all letters, but is consistent ; for digits. ; -- SETFONT [ARIAL BALTIC] 20 1 MAKE "FONTSIZE FIRST BUTFIRST FONT MAKE "HSTEPS FONTSIZE * 1.5 MAKE "WSTEPS (FONTSIZE / 2) * 1.5 ; Get original coordinates MAKE "ORIGXY GETXY ; Adjust upper-left of text by half the ; calculated height and width of the text PU SETX XCOR - (WSTEPS * (COUNT :MSG)) / 2 SETY YCOR + (HSTEPS / 2) ; Write message and return turtle to the ; origina xy location. PD TT MSG PU SETXY ORIGXY PD END TO BIGHAND :ERASE :ANGLE ; -- ; Draw the minute hand (big hand) for the clock and ; erase if TRUE. The hand is drawn at the specified ; angle. ; -- SETHEADING :ANGLE SETPC "DARKBLUE IF :ERASE THEN SETPC "WHITE SETWIDTH 10 PD FD 100 FOR "W 10 1 [SETWIDTH :W FD 2] PU BK 120 END TO AUTHORINFO CT PRINT "|Written by : Bill Russell for my son Brady | PRINT "|Purpose : To illustrate how simple concepts build| PRINT "| on top of each other to build something| PRINT "| useful, such as a clock. | PRINT "|Date : 11/28/06 | PRINT "|Email : firstname.lastname@example.org | END TO INTRO DRAW CT PRINT "|Welcome to the Ticking Clock demonstration! | PRINT "|Type 'RUNCLOCK' to start or 'AUTHORINFO' to | PRINT "|learn about the author. | END INTRO