Chapter 3 Interaction

TECH 3601 NEW MEDIA PROGRAMMING

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setup()and draw()methods•When your program starts, Processing:• Calls setup() once• Continues to call draw() until

the program ends

Learning Processing: Slides by Don Smith

Program Starts

Call setup()

Call draw()

Program ends

Done yet?

Yes

No

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Tracking the Mouse•Processing keeps track of where the mouse is:• mouseX: The current X coordinate of the mouse• mouseY: The current Y coordinate of the mouse• These are both ‘key words’ that you can use!• Their values change as the mouse moves

•An example:

Learning Processing: Slides by Don Smith

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More Mouse tracks…•Processing also keeps track of where the mouse WAS the last time you left draw():• pmouseX: The previous X coordinate of the mouse• pmouseY: The previous Y coordinate of the mouse

Learning Processing: Slides by Don Smith

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A scribble application

Learning Processing: Slides by Don Smith

Just keep connecting the points where the mouse was and it is now:

Exercise•To get the absolute value: abs(-5) 5•The speed at which the mouse is moving is:•abs(mouseX - pmouseX)•Update the previous example so that the faster the user moves the mouse, the wider the drawn line.•Hint: look up strokeWeight() in the Processing reference.

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Mouse clicks and Key presses

Learning Processing: Slides by Don Smith

Two ‘methods’ that you can write to handle events that might happen:

Processing ‘calls’ your method when events occur: mousePressed()

keyPressed()