PICTURETHIS "SHAREWARE" VERSION RELEASE 2.00 MAY 1, 1989 TUTORIAL, PART 1 OF 2 PARTS Copyright 1988, 1989 by Patricia Y. Williams and Gregory Williams, All Rights Reserved. HortIdeas Publishing, Route 1, Box 302, Black Lick Road, Gravel Switch, KY 40328 U.S.A. Trademarks/Owners: CaptureThis and PictureThis/Patricia Y. Williams and Gregory Williams; Hercules/Hercules Computer Technology, Inc.; IBM and PC-DOS/International Business Machines Corp.; MS-DOS/Microsoft Corp.; Pizazz/Application Techniques, Inc.; PostScript/Adobe Systems Inc.; The Newsroom Pro/Springboard Software, Inc. NOTE: Carefully read all of the terms and conditions of the License Agreement (near the beginning of the READTHIS.1ST file on the documentation distribution disk) PRIOR to using the PictureThis and/or CaptureThis programs. USE OF THE PROGRAM(S) INDICATES YOUR ACCEPTANCE OF THOSE TERMS AND CONDITIONS. GETTING STARTED This is a "hands-on" tutorial designed to introduce you to the major features of PictureThis and CaptureThis by having you actually try them out. Besides learning how to use the programs, you'll also make your first PictureThis drawings. Print out copies of this file and KEYS.TXT for easy reference, and you'll be ready to try PictureThis and CaptureThis. Happy drawing! EXERCISE 1. RUNNING PictureThis 1. Make a backup copy of the PictureThis distribution disks, if you haven't already. If you have two floppy disk drives, you can format two new floppy disks using the DOS "FORMAT" command, then place one distribution disk in drive A and a newly formatted disk in drive B. Copy all of the files on the distribution disk to the new disk by keying in, at the DOS "A>" prompt: COPY *.* B: and then press: ENTER Repeat for the other distribution disk. If you don't have two 2 floppy disk drives, or if you need to learn more about copying files, consult your operating system user manual. Store the original distribution disks in a secure place, and use the backup disks for running PictureThis. The following files are required to tun the tutorial: PICTHIS2.EXE PTS2T.OVR PTS2D.OVR LEAF.TMP LEAF.DRW CAPTHIS.COM or ACAPTHIS.COM To create more room for your working files you should delete the text files from your program disk (#1) after you have printed them. To do this, at the DOS prompt corresponding to the drive with your program disk type: DEL *.TXT and then press: ENTER To use the DOS shell feature of PictureThis, you might want to copy COMMAND.COM to your program disk, also. 2. You MUST have a video board and monitor compatible with CGA medium-resolution (320 x 200) graphics; a monochrome (TTL) monitor with a Hercules-compatible graphics board should work IF it has software or hardware CGA emulation (several inexpensive CGA emulation programs are available, some marketed as "shareware"). To run the PictureThis program (PICTHIS2.EXE), put the backup copy of distribution disk #1 (without a write-protect tab on it) in drive "A" and key in: PICTHIS2 Then press: ENTER The title screen should appear for a few seconds, and then a copyright/ordering information screen should appear. Please read it! When you press a key to continue, a blank screen with a dotted frame and an X-shaped cursor at its center should appear. This is the PictureThis drawing screen. 3. Knowing how to exit from a program can be as important as knowing how to run it! To return to DOS from PictureThis, no matter where you are in the program, press: Esc 3 (repeatedly if necessary) until you see the prompt: Quit PictureThis? (Y/N) Then press: Y if you really want to quit; press any other key (including, but not limited to "N") if you don't. Note: with a few exceptions, PictureThis is INSENSITIVE TO CASE (for example, "Y" is treated the same as "y"). Try it: press "Esc" and then, when you see the exit prompt, press any key other than "Y" -- the prompt goes away and you're still in PictureThis. Press "Esc" again, and then "Y" -- you're back at the DOS command prompt. Run PictureThis again by keying in "PICTHIS2" and then pressing "ENTER" as before. 4. Press "R" and you should hear a BEEP, meaning that "R" is an invalid key, currently (but not always) inappropriate. Don't worry about pressing invalid keys: nothing else will happen except a BEEP. If you get tired of hearing BEEPs, you can toggle them off by pressing: H Try it: press "H" and then "R" -- no BEEP. When you press "H" again and then "R" -- the BEEP is back, AND an error message appears. Press a key to make the error message go away. When you press "H" and then "R" a third time, you're back to just a BEEP. The "H" ([H]ear) key toggles among three responses to invalid key inputs: BEEPing with no error messages, no BEEPing and no error messages, and BEEPing with error messages. Note: not all invalid keys have associated error messages (a complete list of error messages can be found in the user manual). When error messages are toggled on, special prompts will appear during certain infrequently used and/or possibly confusing operations. We recommend that beginners toggle on BEEPing with error messages and prompts, so, if you already pressed "H" three times, as directed above, press it twice more. To make sure BEEPing with error messages and prompts are now toggled on, press: W This ([W]hat's Happening) key toggles a status box on and off at the bottom of the drawing screen. Press "W" a few times to see the box appear and disappear, ending with it toggled on. For now, you can disregard most of contents of the status box, but there should be an "H+" in it to denote that BEEPing and error messages/prompts are on. If there is just an "H " in it, only BEEPing is toggled on, and if there is an "H-" in it, neither BEEPing nor error messages/prompts are toggled 4 on. Press the "H" key a few times to watch the symbols cycle among the three possibilities, and stop with "H+" showing. Then press "W" to toggle the status box off. Currently valid keys are listed in help screens which can be accessed (except when a menu is showing) by pressing: ? Try it. Then press a key to return to the drawing screen. EXERCISE 2. ABOUT FILES 1. The "ultimate products" of PictureThis are files written in the PostScript page description language, which contain all of the information about your drawings needed by PostScript-equipped laser printers and imagesetters to generate high quality prints. Three other kinds of files are involved in the production process: template files, drawing files, and clip art files. CGA (medium- or high-resolution) graphics screens can be captured in template files by using the CaptureThis (or Alternate CaptureThis) program; the files can then be imported into PictureThis to provide background screens for tracing. Drawing files are used to store and retrieve information about your drawings in a format usable by PictureThis (which can't read PostScript); you can save a drawing-in-progress in a drawing file for later recall. Clip art files can save parts of drawings for use in other drawings. Following the instructions in this tutorial, you will work with sample template and drawing files, and you will create a template file, two drawing files, two clip art files, and two encapsulated PostScript files. The recommended extensions for names of PictureThis template, drawing, clip art, and PostScript files are, respectively, ".TMP," ".DRW," ".CLP," and ".EPS." Access the file operations menu by pressing: F10 In response to the menu, press: R A prompt for a template filespec appears with a "wild card" file specification in the second line. This file specification consists of your current directory (see your DOS manual) and "*.TMP." Press "ENTER" and a directory page will appear with all files listed that match this file specification with the first file highlighted. Change the highlighted file to LEAF.TMP with the cursor keys (if necessary) and press "ENTER." The drawing screen will reappear and you should now see a representation of a leaf, which can be used as a tracing template for your drawing. Note: importing a template file erases a template already on the screen. In Exercise 15, 5 you'll learn how to capture CGA graphics screens for use as templates. 2. Press "F10" to access the file operations menu a second time. In response to the menu, press: G A prompt for a drawing filespec appears with a "wild card" file specification on the second line (your current directory and "*.DRW"). Press "ENTER" and a directory page will appear. Change the highlighted file to LEAF.DRW with the cursor keys (if necessary) and press "ENTER." The drawing screen will reappear with the same template, plus curves (having a color different from the template colors) along the leaf's edges and stem. These curves are a drawing previously made with PictureThis. Note: importing a drawing file erases a drawing already on the screen. In Exercise 7, you'll learn how to save a drawing file. 3. Encapsulated PostScript files are text files which can be written, but not read, by PictureThis. To write such a file for the leaf drawing, again access the file operations menu by pressing "F10" and then, in response to the menu, key in: W Respond to the next nine prompts by pressing: ENTER to accept the defaults (refer to the PictureThis user manual for more information). Then, in response to the prompt for a filespec, key in: LEAF.EPS and then press: ENTER Key in your name in response to the "Created by?" prompt, then key in: Leaf in response to the "Title?" prompt, and, in response to the next prompt, press: ENTER to accept the default date. The file will then be written to disk, in the current directory. If you want to take a look at the PostScript file just 6 saved, you can shell to DOS. (Note: COMMAND.COM must be present in the current directory or in a directory specified in the PATH command; see the DOS manual.) First access the file operations menu again by pressing "F10." Next, in response to the menu, press: D The DOS prompt will appear. At the DOS prompt, key in: TYPE LEAF.EPS and then press: ENTER To stop the scrolling temporarily, press (simultaneously): Ctrl and: S Press any key to begin scrolling again. Now return to where you were by keying in "EXIT" followed by "ENTER" at the DOS prompt. EXERCISE 3. THE SCREEN 1. To access the miscellaneous menu, press: F9 In response to the menu, press: P to select a different palette. There are six palettes (three normal and three intense) available, although your video card and/or monitor might not show each palette differently. Use one of the number keys on the Main Keyboard to respond to the next prompt. For an intense palette (not available with some video cards and monitors), press "SHIFT" simultaneously with the number key. Try this ("F9" then "P" then a number key, shifted or not) a few more times to see which palette choices are available with your video card and monitor. You can stop with the palette you find most pleasing. 2. Press: T This ([T]emplate) key toggles the template off, so you see 7 only the drawing. It does NOT erase the template permanently. Press "T" again to toggle the template on. Press: R This ([R]emove and [R]estore) key toggles the drawing off, so you see only the template. It does NOT erase the drawing permanently. Press "R" again to toggle the drawing on. Press: D This (re[D]raw) key erases both the template and the drawing, and then immediately draws them again -- useful for removing "garbage" (extra and/or missing parts of curves) that appears occasionally on the screen (especially when erasing or manipulating objects, as explained later in this tutorial). Such "garbage" may not be aesthetically pleasing, but it ISN'T included in drawing or PostScript files made with PictureThis, and eliminating it completely would considerably slow the program's operation. The "D" key also has another function, described in step 5 of this Exercise. Press: C This ([C]lear) key accesses a prompt to PERMANENTLY erase the drawing! The drawing will be lost FOREVER unless you saved it previously in a drawing file. In response to the "Clear screen?" prompt, press any key other than "Y" to make the prompt disappear. Press "C" again and then (since you can easily import LEAF.DRW again) press: Y Only the template remains. Press "F10" and then "G"; press "ENTER" and use the cursor keys (if necessary) to highlight LEAF.DRW. Press "ENTER," and the leaf drawing appears again. 3. Note that the curves comprising the drawing have small boxes at their ends. To see the drawing without these boxes (and with no screen border), press: V This ([V]iewscreen) key is useful when you want to find out how much of the available memory a drawing has used. Press: U 8 to toggle on the memory [U]sed box when the viewscreen is on (press "U" again to toggle the box off). For more information on memory limits, see the user manual. No drawing can take place when the viewscreen is on (the cursor is gone!). Now press "Esc" to return to the drawing screen. 4. To see an approximation of the drawing as it will appear when output on a PostScript printer, press: Q This [Q]uickshow screen shows correct line widths, fills, etc. (see Exercises 6 and 9). By using the Print Screen function (see your operating system manual for more information), you can "dump" the Quickshow screen to a dot matrix printer for a low-resolution print of the drawing, assuming that you have previously installed a memory-resident graphics printer driver program appropriate for the CGA graphics mode (such as GRAPHICS.COM, supplied with PC-DOS, or a more sophisticated program such as Pizazz). Now press "Esc" to return to the drawing screen. 5. Three screen magnifications are possible: 100%, 300%, and 50%. You see the 100% screen currently. Switch to the 300% screen by pressing (on the Numeric Keypad): + Now switch back to the 100% screen by pressing (on the Numeric Keypad): - And now switch to the 50% screen by pressing "-" (on the Numeric Keypad) again. Back to the 100% screen by pressing "+" again. So: "+" for magnifying, "-" for demagnifying. When the magnification is "zoomed" to 100% or 300%, the screen becomes centered on the cursor. When working on the 100% or 300% screen, you can center the screen on the cursor without "zooming" by pressing: X The [T]emplate, [R]emove and [R]estore, and [C]lear keys work the same way with the 50% and 300% screens as with the 100% screen, but the re[D]raw key also switches among four algorithms for compressing the template (the practical significance is that some template lines might be visible only when some of the algorithms are used). Press the Numeric Keypad "-" to switch to the 50% screen, and then press "D" repeatedly as you watch for subtle changes in the template. (It might help to toggle the drawing off with "R" for a better view.) If you leave and then return to the 50% screen, the template will look as it did when you left the 50% screen. Test this if you want. 9 The viewscreen and the Quickshow screen can also be "zoomed," using the "+" and "-" keys on the Numeric Keypad. 6. You can scroll around the 100% and 300% screens (but not around the 50% screen). Use the number keys (except "5") on the Numeric Keypad with "SHIFT" pressed simultaneously or "NumLock" toggled on. Try it on both the 100% and 300% screens. Note that the scrolling increment is about one- quarter of the screen, either horizontally or vertically (or both, for diagonal scrolling). Also note that when the cursor reaches the edge of the screen during scrolling, it is "dragged along" by the scrolling, so it remains at the edge of the screen. The viewscreen and the Quickshow screen can also be scrolled, using the same keys. 7. You can center the frame (the rectangular dotted box) on the screen for the 100% and 300% screens by pressing (simultaneously): 5 and: SHIFT You can center the frame on the screen and simultaneously center the cursor in the frame (this is called "zeroing" the screen) by pressing: Z The viewscreen and the Quickshow screen can also be centered and zeroed (even though the cursor doesn't show!), using the same keys. EXERCISE 4. CURSOR MOVEMENTS 1. To move the cursor anywhere on the screen, use the number keys (except "5") on the Numeric Keypad (with "SHIFT" not pressed and "NumLock" toggled off). Initially, the cursor moves one pixel horizontally or vertically (or both, for diagonal movements) each time a number key is pressed. Practice moving the cursor around, and then press (on the Numeric Keypad, with "SHIFT" not pressed and "NumLock" toggled off): Ins Now use the Numeric Keypad number keys again to move the cursor. The cursor moves ten pixels each time a number key is pressed. Thus, the "0" key toggles between cursor movement increments (you can think of these as cursor "speeds") of one and (initially) 10 pixels. The "fast cursor speed" can be changed from 10 to any number between 2 and 99; see the user manual on how to do this. 10 2. To move the cursor to a corner of the frame press the "Ctrl" key simultaneously with one of the four corner keys on the Numeric Keypad ("Home," "End," "PgUp," or "PgDn"). The cursor will jump to the appropriate corner of the frame. 3. Another way to move the cursor around a drawing is to use the endpoint selection operation, which you can begin by pressing (on the Numeric Keypad, with "SHIFT" NOT pressed and "NumLock" toggled off): Del The cursor moves to a nearby curve endpoint (usually, but not always, the nearest endpoint), all of the curves with that endpoint become dashed so they can be easily identified, and (if H+ is toggled) a prompt to press "+," "-," "SPACE" or "ENTER" appears. Now press: + several times, so the cursor moves to all of the curve endpoints, in turn. Next, press: Esc and the cursor returns to where it was before "Del" was pressed. In general, "Esc" cancels the current operation (in this case, endpoint selection), and restores the program to its state just before the operation began. Again press the Numeric Keypad "Del"; press "+" a few times; then press - to return to the previous endpoint. If you press "-" immediately after pressing "Del," the cursor jumps to the farthest endpoint. Try it. In general, "+" (or "SPACE") takes the cursor forward through the sequence of endpoints arranged by closeness to the original cursor position, and "-" takes the cursor backwards through the same sequence. To select an endpoint, press: ENTER when the cursor is on the desired endpoint. The cursor remains at the endpoint, and the dashing of the curves with that endpoint go away. 4. Press: P This ([P]osition box) key toggles the position box (at the bottom right corner of the screen) and the relative position box (at the top of the screen) on and off in a three-way 11 toggle (try it, and stop with only the position box on). The number on the left is the horizontal distance of the cursor from the left of the frame in INTERNAL UNITS; the number on the right is the vertical distance of the cursor from the top of the frame in INTERNAL UNITS. Watch the numbers as you move the cursor around the screen. Try it at all three screen magnifications. What are internal units? PictureThis saves the position of the cursor and all other elements in internal units (ius). These are integer values that allow much finer resolution than the screen. (On the 100% screen there are 24 ius per pixel; on the 50% screen there are 48 ius per pixel; on the 300% screen there are 8 ius per pixel.) You can move the cursor in internal unit increments as well as in pixel increments. To switch to internal units, press: I Now move the cursor around the screen again. Try it at all three screen magnifications. The Numeric Keypad "0" still toggles between 1 and 10 (or a different user-set fast speed) units per cursor movement increment, but now the units are internal units, not pixels. Press "I" again to switch back to pixels. Press "W" and the fifth character from the right will be either "I" for internal units or "E" for external units (or "G" for grid, see the user manual). The number following this indicator is the cursor speed: either 1 or the current fast cursor speed (10 currently). The two characters following the cursor speed abbreviate the current units and should be "PX" for pixels. Other possible units are inches, points, picas and points, centimeters, and millimeters. (See the user manual for information on how to change to different units.) EXERCISE 5. DRAWING CURVES 1. By following the instructions in the remainder of this tutorial, you'll draw a leaf with three leaflets, using the template already on the screen as a guide for the first leaflet. But first, you need to erase the already completed leaf drawing. Press "C" and then "Y" to do this. Now make sure that the 100% screen is on (see Exercise 3, step 4) and centered (see Exercise 3, step 7). 2. Curves drawn in PictureThis are cubic Bezier curves, which means that they are each completely determined by two endpoints and by two "control points" (one associated with each endpoint) which specify curve shape. To draw a curve, you first set (specify the location of) its first endpoint, then you set its second endpoint, then you position its control points, and finally you set the curve. Before you begin drawing, remember what was said earlier about using "Esc" to cancel the current operation. If you become confused or frustrated at any point, just press "Esc" to restore the program to its state just before you began the 12 current operation. Also, we recommend that you press "W" to toggle the status box on (if it is not already showing) while learning to draw; in the status box is an indicator of the current operation or state (before you begin drawing, it says "FREE"). Start with the leaf's stem. Move the cursor to the tip of the template leaf, at the upper left. The internal units of the tip (shown in the position box) used when making the drawing saved in LEAF.DRW are 972 (horizontal), 972 (vertical), but you don't necessarily have to duplicate that drawing exactly. When the cursor is where you want it, press: F1 This key is always used to set the endpoints of curves. It now says "LINE" in the status box. Now that you have one endpoint defined, move the cursor to the other end of the stem, at the top of the small oval. The ius used when making the drawing saved in LEAF.DRW are 6492, 3708, but, again, you needn't duplicate that drawing exactly. When the cursor is where you want it, press "F1" again to set the curve's second endpoint. The curve is really a line at this stage, but the status box says "CURVE" because you can now change the curve's shape. Move the cursor away from the second endpoint, up and to the left, and the line becomes curved. You are moving the control point associated with the second endpoint (which we'll call the "second control point") away from the second endpoint. Press: F2 This key is always used to switch the cursor between control points after both endpoints of a curve have been defined. You can see that the cursor jumped to the first endpoint, which is where the "first control point" is initially located (control points are always at their associated endpoints until you move them). A dot marks the position of the second control point. Now move the cursor away from the first endpoint, down and to the right, and you can make the curve have an S-shape. You are moving the first control point away from the first endpoint. Now press "F2" again. The cursor jumps back to the second control point, leaving a dot to mark the position of the first control point. Now you can move the second control point again. You can keep pressing "F2" and moving the cursor, in turn, positioning both control points to shape the curve the way you want it. The LEAF.DRW drawing has 1596, 1572 for the first control point's coordinates, and 5532, 2580 for the second control point's coordinates. Now you need to set the curve. Press: F3 13 This key is always used to set a curve after its two endpoints have been set and its two control points have been positioned. The status box says "FREE" again. You've just drawn your first curve in PictureThis. Note that the cursor ends up at the second endpoint; this makes it easy to draw a succession of connected curves. Now for the end of the stem. The cursor is already where the first endpoint of the next curve should be. There is an important rule for drawing with PictureThis which is exemplified here: IF YOU WANT CURVES TO CONNECT PRECISELY, MAKE SURE THAT THEY SHARE AN ENDPOINT WHERE THEY CONNECT. If you simply move the cursor by eye, it can LOOK as if the cursor is positioned exactly at an endpoint, yet it can be off by as many as 47 internal units (on the 50% screen). The ways to be sure that you are at a previously set endpoint are either to end up there after setting a curve (as you just did) or to use the endpoint selection operation, as described in step 3 of Exercise 4. Now switch to the 300% screen for a better view of what you're doing. You will draw only the right side of the oval because this leaflet will be attached to others in the final drawing. Press "F1" to set the first endpoint of the right side of the oval. In LEAF.DRW, the coordinates of the second endpoint are 6444, 3828; it also has 6588, 3772 for the coordinates of its first control point, and 6492, 3868 for the coordinates of its second control point. Switch back to the 100% screen and press "SHIFT" and Numpad key "5" simultaneously to center the frame on the screen. Next, draw the bottom curve of the stem, starting at the endpoint at the bottom of the stem end you just completed (the cursor should already be there), and ending at the leaf tip endpoint. Remember to use the endpoint selection operation to make sure that you are at the previously defined tip endpoint. The LEAF.DRW bottom stem curve uses first control point coordinates 5556, 2628, and second control point coordinates 1356,1668. EXERCISE 6. MODIFYING CURVES 1. If you happen to make a mistake when drawing a curve, or find later that a curve needs to be different, you can erase or change the curve. To try this, press: F4 This key first will jump the cursor to the nearest endpoint just as if you had pressed the "Del" key. In this case the cursor should already be on the tip endpoint, so select that endpoint by pressing "ENTER." One of the curves with the endpoint where the cursor is located becomes dashed and a prompt appears. You can switch the dashing between curves by pressing: SPACE, +, or - 14 (try it a few times). Dash the LOWER of the curves, and then press: ENTER The curve modification menu appears. Now press: E A prompt appears asking if you want to erase the curve. If you answer "Y," the curve will be erased permanently. Go ahead and press "Y." (If you answer with "N" (or any character except "Y" or "y"), the curve will not be erased and the curve modification menu will reappear.) 2. You will have to redraw the curve, but this time, press "F1" to define the curve's first (upper left) endpoint, then use the endpoint selection operation to move to the curve's other endpoint, and immediately press "F3." This establishes a straight line between the two endpoints. Now press "F4" to again access the curve modification menu. Choose either endpoint of the straight line and then choose the straight line to modify. This time you want to change the line to a curve, so press: C The menu and the dashing go away; A CURVE WHICH CAN BE SHAPED IS NOW ON TOP OF THE ORIGINAL LINE. It says "CHANGE" in the status box. Move the cursor with the Numeric Keypad number keys to shape the new curve; notice the dashed line still in place to show you what the original curve looks like. When you are changing a curve, you can use the "F2" key to switch between control points, as usual. When the new curve's shape is acceptable to you, press "F3" to define the new curve. The old curve (represented by the dashed line) is erased. 3. Press "F4" again to access the curve modification menu. Choose an endpoint and one of the long curves as usual and press: L A line parameter menu appears which allows you to change the chosen curve's line weight (thickness), line gray (white to black), and linecap (the way the line ends). The top line of the menu lists the parameters that you can change. The second line lists the current values of the parameters. Press: W Now you can key in a new line weight value in PostScript points (1 point is 1/72"). Try 20 points. Now press "K" to save the new line weight, followed by "Q" to see the Quickshow screen. Notice that one of the long curves is now 15 much thicker than the other. Press "Esc" to return to the drawing screen. Press "F4" again and choose the thick curve again. Press "L" again and then press: G Now you can change the gray percentage of the curve. The gray values range from 0 (white) to 100 (black). Try 50 and press "K" to save the new line gray. Now look at the Quickshow screen. Press "Esc" to return to the drawing screen. Press "F4" again and choose the thick curve. Press "L" twice. Now you can change the linecap (the way the line ends). The default linecap is "Round," and you can see on the Quickshow screen that the current thick curve has rounded ends. The other two choices are "Butt" (the cap ends at the curve end and is squared off) and "Square" (the linecap projects half the width of the curve beyond the end and is squared off). Try these and check the results on the Quickshow screen. You should experiment with altering the three line parameters, checking the results with the Quickshow screen. You can change any combination of the three parameters at one time before you press "K" for keep. If you press "Esc" while at the line parameter menu, NONE of the changed values will be saved. Note that a white (0 line gray) curve will not show at all on the white background, but will show where it crosses another darker curve. While you are experimenting, change a line weight to -1. This changes the curve to a "construction" curve that shows on the drawing screen as a dotted curve and doesn't show at all on the Quickshow screen or the PostScript output. When you are done experimenting, change all curves back to a line weight of 1, a line gray of 100 (black), and round linecaps. EXERCISE 7. CUTTING CURVES 1. All that remains to complete your drawing's outline is adding the leaf edge curves. There is a potential problem here: each of the (two) edge curves share the leaf tip endpoint, but they also need to intersect the stem curves where there AREN'T endpoints. Recall that precise intersections of curves occur ONLY at shared endpoints. We need to ADD an endpoint "in the middle" (actually, nearer to the right end) of each of the stem curves. This is possible by "cutting" each of the curves into two curves which are very similar to the parts of the original curves on both sides of the newly added "middle" endpoint. To begin the cutting operation, press: F5 The cursor will jump to the nearest endpoint, just as if you had pressed "Del". Select the bottom endpoint of the upper 16 stem side; next select the upper stem side by pressing "+" until it is dashed and then pressing "ENTER." Now you can move the cursor ALONG the curve with the cursor keys until the cursor reaches the point at which the leaf edge meets the stem (LEAF.DRW uses 6216, 3456). Press "F3" and PictureThis will automatically cut the original curve into two curves at the newly chosen "middle" endpoint. Now do the same operation for the lower stem side (in this case, LEAF.DRW uses coordinates 6096, 3480 for the new "middle" endpoint). 2. Now complete the leaf by drawing the upper and lower leaf edges using the newly established endpoints. First draw the lower leaf curve starting at the lower endpoint. For the lower leaf edge, LEAF.DRW uses 1380, 2868 and 4344, 3892 for the control point coordinates. Next draw the upper leaf edge starting at the leaf tip. For the upper leaf edge, LEAF.DRW uses 6216, 1406 and 3852, 1164 for the control point coordinates. 3. At this point you should save your drawing! Press "F10" to access the file operations menu, then press: S A prompt will appear asking if you want to save the drawing as LEAF.DRW. Answer with "N". In response to the next prompt key in: MYLEAF.DRW and press: ENTER It should only require a few seconds for your drawing to be saved. EXERCISE 10. DRAWING BOXES AND OVALS 1. Turn the template off by pressing "T," and erase your drawing by pressing "C" followed by "Y." 2. To draw a box, move the cursor to where you want a corner of the box and press: B Now move the cursor away from the first corner and a box will follow. When you are satisfied with the shape of the box press: F3 Your box is made of four straight lines connected at four corner endpoints. You may treat the each of the four straight 17 lines as you would treat any other curve. 3. To draw a square, press "B" at one corner of the square and then press: S Two guidelines will appear through the square's corner at 45 degrees to the horizontal. Now move the cursor along one of the guidelines by pressing one of the "diagonal" cursor keys ("7," "9," "3," or "1" on the Numeric Keypad). A square will follow. You can press the diagonaly opposite cursor key to go in the other direction along the same guideline. If you want to move the cursor along the other guideline, you must first press: F2 Try it. The square disappears and the cursor moves back to the original corner. Now you can move along the other guideline with the other two "diagonal" cursor keys. When you are satisfied with the square, press "F3" and your square will be established. If the squares that you draw using this method do not appear to be true squares, the aspect ratio of your screen must differ from the default. To adjust this, see the user manual. 4. To draw a circle, press: O with the cursor positioned where you want the center of the circle. Two guidelines will appear through the center, one horizontal and the other vertical. Move the cursor along the horizontal guideline with the "4" and "6" Numeric Keypad keys. A circle is drawn, centered on the guideline cross, passing through the cursor. When you are satisfied with the circle, press: F3 Your circle is set. It consists of four Bezier curves that can each be treated as any other curve in PictureThis. The cursor will end up in the center of the circle (this facilitates drawing concentric circles). If the circles you draw do not look like true circles, you will have to adjust your screen's aspect ratio (see the user manual). 5. To draw an oval (ellipse), press "O" with the cursor where you want the center of the oval, and start by drawing a circle as above. When the circle is a reasonable size, press: F2 18 The cursor jumps to the top or bottom of the circle, where the circle crosses the vertical guideline. Now you can change the circle to an oval by moving the cursor up and down (with the "8" and "2" Numeric Keypad keys). You can jump the cursor back to its previous position on the horizontal guideline (to change the horizontal dimension again) by pressing "F2," and so on. When you are satisfied with the oval, press: F3 The oval is set as four Bezier curves, and the cursor jumps to the center of the oval. 6. Draw several boxes, squares, circles, and ovals, making some of them overlap. Try pressing "Esc" at various points while drawing, to see what happens. EXERCISE 9. MODIFYING TRAILS 1. A TRAIL in PictureThis is a group of curves, usually continuously connected endpoint to endpoint. Trails can be filled with gray shades and combined to form objects which can be further manipulated. Whenever you draw a curve it is automatically put in a trail. If the NEXT curve you draw has its FIRST endpoint in the SAME place as the previous curve's SECOND endpoint, the second curve is put in the same trail, and so on. When you drew the leaf edges in Exercise 7, step 2, you drew them so they would form a continuous trail. The curves that form an oval or a box are also automatically placed in a trail. 2. Now you will fill some of the boxes, circles, and ovals that are on your screen. To access the trail menu, press: F6 Then press: F to fill a trail. The cursor will jump to the initial point of one of the trails on screen (the initial point is the first endpoint drawn in a trail) and the trail will be dashed. Press "+," "SPACE," and "-" repeatedly until the trail you want to fill is dashed (in this case just pick any box or oval), and then press "ENTER." A prompt will appear, stating the current gray fill percentage and asking for a new one. The current fill should be -1%, meaning that the selected trail is NOT filled. Enter a number between 0 (white) and 100 (black). The screen will be unchanged (since fills do not show on the drawing screen), so press "Q" to see the Quickshow screen. The trail you have chosen will be filled with a pattern representing the shade of gray you have chosen. Now press "Esc" to return to the drawing screen. Fill some more ovals and boxes with different gray percentages and 19 check the results on the Quickshow screen. If you fill some overlapping trails you will notice an important property about PictureThis (and PostScript) fills: they are "opaque." If a trail overlaps another trail, and the trail "in front" is filled, the portions of the other trail that are "behind" the first trail will not be visible on the Quickshow screen or on the PostScript output. Watch overlapping trails being drawn on the Quickshow screen. First the "behind" trail will be completely drawn; then the "in front" trail will be drawn, obscuring part of the "behind" trail. It is as if the "in front" trail were "pasted" on the drawing. The order in which trails are "pasted" on the Quickshow screen (and the PostScript output) is initially determined by the order in which they are drawn (the earliest are "pasted" on first), but this layering can be changed easily (see Exercise 11, step 5). 3. On the drawing screen, scroll your drawing so that an edge of the frame runs across your computer's screen (see Exercise 3, step 6). Now draw a circle so that it is partially within the frame and partially outside the frame. Fill the circle and press "Q." Notice that only the part of the circle WITHIN the frame appears on the Quickshow screen. That is because the frame "clips" your drawing: only portions of a drawing WITHIN the frame will show on the Quickshow screen and on the PostScript output. It is easy to change the size and location of the frame (see the user's manual). 4. If you have many elements in a drawing, the Quickshow screen may take a long time to finish drawing. To stop it before it completes drawing, press "Esc." When you press "Esc" a second time, the drawing screen will reappear. Try it. 5. Try erasing one or more trails. To do this, press "F6" to bring up the trails menu, then press "E" for erase. A trail will be dashed. Choose a trail by pressing "+," "-," and "SPACE" repeatedly, then press "ENTER." A prompt will appear asking if you want to erase the chosen trail. Answer "Y" and the entire trail will be erased. 6. Now you will change the line parameters of some trails. First press "F6" to access the trails menu again; then press: L Choose a trail in the normal mannner. When you press "ENTER," a line menu will appear. This menu is the same as the line menu for a single curve (see Exercise 6, step 3), except it has an added parameter: the "join" of the trail, which refers to how two curves of a trail are joined where they connect at their endpoints. If the second line for any of the parameters says "MIXED," then the curves in the chosen trail do not all have the same value for that parameter. You can change the line weight, line gray, and linecap of 20 ALL the curves in the trail, just as you changed them for an INDIVIDUAL curve in Exercise 6, step 3. Try it and check your results with the Quickshow screen. Try changing a filled trail's line weight to -1 and check the Quickshow screen; you should see a filled area with no boundary. Also try changing the join for a box with thick black lines (say, 40 points). The three possibilities are "Mitered" (the default for boxes), "Rounded," and "Beveled." Look at the joins on the 300% screen. 7. Now return to your leaf drawing by pressing "F10," "G," and keying in "MYLEAF.DRW." Notice that the current drawing is cleared before the new drawing is brought in. Center the frame (if it isn't already centered) with "SHIFT" + "5." Fill the trail made of the two edges of the leaf with some reasonable gray value (say 50%). (It was drawn as a continuous trail in Exercise 7, step 2.) If you look closely, you will notice that the two leaf edges do not form a closed trail - there is a small gap at the stem. When a trail that is not closed is filled, PictureThis automatically closes the trail by drawing a straight line of line weight -1 (a construction line) from the last endpoint in the trail to the first one, and filling the resulting closed trail. In this case, it doesn't matter, but you will usually want to fill only closed trails. After you have filled the trail, change all the curves of this trail to a line weight of -1. Check your results on the Quickshow screen. Notice that the stem is mostly blocked out now; you will correct that in the next step. EXERCISE 10. DEFINING A TRAIL Many trails are automatically defined when you draw them, but sometimes you need to define a new trail of existing curves. The stem of the leaf was drawn as a continuous trail, but since you erased one of its curves and redrew it, it is no longer a single trail. This gives you the opportunity to learn how to define trails. Press "F6" and then press: D to start defining a new trail. The cursor will jump to the nearest endpoint (just as if you pressed the "Del" key). Move the cursor using "+," "SPACE," and "-" repeatedly until it is on one of the endpoints of the stem; press "ENTER." One of the curves emanating from the chosen endpoint will now be dashed. If it is a stem curve, press "ENTER." Otherwise, press "+," "SPACE," and "-" repeatedly until a stem curve is dashed and then press "ENTER." The chosen curve will become dashed-and-dotted, and the cursor will jump to the other end of the curve. In the same manner, choose the next stem curve, etc., until the cursor is back to the original endpoint, then press "D." The new trail is now defined. A prompt appears asking for a fill value of the new trail; enter some reasonable value (say, 75%) CONSIDERABLY DIFFERENT from the 21 fill value of the leaf. Now a prompt appears asking if you want to change the line parameters of all the curves in the new trail. Answer "Y" and change the line weights of all the curves to -1. View your drawing on the Quickshow screen. Now the stem is again "in front of" the leaf, because the stem trail was defined more recently than the leaf edge trail.