Section 3: Editing an Actor's Motion Algebraically and Graphically |
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F3: Edit enables editing of actor’s motion through various representations.
By selecting F3: Edit: Actor  A or B, you can change the starting place (the Initial Position) of each Actor. On selection, the Actor should blink. The position of the objects can be moved by pressing the cursor keys. |
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Use the left and right cursor keys to change the initial position of the Actors in a horizontal animation (and up and down cursors for vertical motions). When you are happy with the position, press Enter to commit. Notice that the graphical view (if shown) will also update as the representations are linked. So changing the initial position of an Actor affects the b in y=mx+b. |
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To edit the Position graph of Actor A, select F3: Edit: POS A by using your left and right cursor keys, then the editing method of your choice including Function Editing (FnEdit), Graphical Editing (GrphEdit) and Point Editing (PtEdit). The editing methods are the same for the Velocity and Acceleration graphs. These are edited by first selecting VEL or ACCEL . To view the Velocity graph, select VEL Graph, and press ENTER. You can similarly select the Acceleration graph. |
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| Note |
| All Edit options (FnEdit, GrphEdit, PtEdit) may not be available in each document. |
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FnEdit: Here you can to change the function for each segment of the graph. Input fields for the parameters of each function will be accessible by moving the cursor keys. Input values for each parameter, e.g., m and b in y=mx+b. The soft keys SAVE and EXIT correspond to the hard keys (F1 and F5) beneath them. |
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GrphEdit: Select Graph Edit for the options Add, Insert, and Delete to be available. After selecting Graph Edit, hotspots will allow you to change the graph of the Actors. Add will add a segment to the end. Insert will add a segment where you have the hotspot. A hotspot is a blinking cursor at the end of a line segment. With the cursor keys, move it up or down will change the slope; move it left or right will change the duration. To move between segments, press 2nd and the left or right arrow key. You will see the Hotspot move to the right when you press 2nd and the right arrow, to the left when you press 2nd and the left arrow. When the hotspot is at the beginning of your first segment, you can change your starting position and time as well. |
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You can Add, Insert and Delete (or Point Edit) segments by selecting F3 again whilst in Edit Mode. All other menus will be unavailable until you commit your graphical edits by pressing Enter or 2nd QUIT [MODE]. Here we will add another piece. All inserts are at the point of the flashing hotspot. |
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In this example, we have added another piece and used the down cursor key to make its slope negative. Pressing ENTER will commit your edits. |
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PtEdit: Select Point Edit to change the hotspot according to a specific ordered pair. Now you can edit the position of hotspots via an input screen for an ordered pair. This option is useful when hotspot movement does not allow the user to obtain the specific time and position desired. |
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Since we force continuity, the position graphs will move accordingly with the new location of the hotspot. In our example, we have changed the hotspot location of the left side of the second piece so that it meets A at 4 seconds. Move between hotspots to change the input fields. Pressing the right cursor key will update the graph. Pressing ENTER will commit the changes. |
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| An Actor’s position with respect to time can also be altered by editing other graphical representations of the motion, for example, Velocity graphs and Acceleration graphs. You will see in other activities that we can use non-motion contexts and the labels for each of these menus can be altered to suit various activity purposes. |
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| Note |
| All graphs may not be available in each document. |
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F2: View: Graph VEL to view the Velocity graph. |
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You may choose to edit the Position function (F3: Edit: POS ) while viewing the Velocity graph. In this circumstance, you can view the change in the Velocity graph when you change the slope (m) or the y-intercept (b) in y=mx+b. |
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You may also want to edit the Velocity function (F3: Edit: VEL ) while viewing the Position graph. In this circumstance, you can view the change in the Position graph when you change the Velocity function. |
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F2: View: Graph ACCEL allows you to view the Acceleration graph. |
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You may choose to edit the Position function (F3: Edit: POS ) while viewing the Acceleration graph. In this circumstance, you can view the change in the Acceleration graph. |
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You may also edit the Velocity function (F3: Edit: VEL ) while viewing the Acceleration graph. In this circumstance, you can view the change in the Acceleration graph when you change the Velocity function. |
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