Erasing the Graphics Canvas
DRAW CLEAN CLEARSCREEN UNDO [button] REDO [button]
Now that you have learned to draw with the turtle, you will want to erase your picture and start a new one.
There are three commands to do this. Let’s see how they are different.
DRAW
DRAW erases the Graphics canvas, where the turtle draws, and totally resets the turtle.
Here is what DRAW does:
- Clears (erases) the drawing canvas.
- Resets the turtle to its original state.
- Moves the turtle to its Home in the center of the screen.
- Shows the turtle.
- Puts the pen down.
- Sets its shadow to 0.
- Unlocks its heading.
- Sets the drawing canvas to
WRAPmode. - Removes any bounds you have set (see Graphics Panel Commands).
If you were using multiple turtles, DRAW puts them all back to their original values and makes Turtle 0 be the active turtle. To learn how to control more than one turtle, see the page with Multiple Turtle commands.
» Things to Watch Out For
The [UNDO] button (see below) does not “undo” a DRAW command.
CLEAN
CLEAN erases the Graphics canvas, but does not change the turtle’s position or heading.
» Things to Watch Out For
You can use [UNDO] (see below) to “undo” a CLEAN command.
CLEARSCREEN
CS
CLEARSCREEN is like CLEAN, but it moves the turtle back to its Home position, pointing straight up.
» Things to Watch Out For
You can use the [UNDO] button to “undo” a CLEARSCREEN command.
UNDO [button]
Clicking the [UNDO] button in the Icon Bar “undoes” the last graphics command(s) you typed.
If you have entered many commands on the same line, clicking the [UNDO] button undoes all of them at once.
REPEAT 10 [FD 20 RT 36]
Click [UNDO]. In this case, clicking the [UNDO] button erases your entire drawing!
If you enter one command on a line, clicking the [UNDO] button will undo just the last instruction.
FD 20
RT 36
FD 20
Click the [UNDO] button. This will undo only the last FD 20.
» Things to Know
The [UNDO] button in the menu bar will become dim when there is nothing more to Undo.
UNDO used to be a command in previous versions of Logo, but has been removed in Logo6.
REDO [button]
Typing the [REDO] button in the Icon Bar “redoes” the last line of graphics commands you have entered.
» Things to Know
The [REDO] button in the menu bar will become dim when there is nothing more to Redo.
REDO used to be a command in previous versions of Logo, but has been removed in Logo6.