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Topic: question on an example-program (Read 396 times) |
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der_rabe
 
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question on an example-program
« on: Dec 26th, 2003, 12:21pm » |
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i browsed through the example-codes which came with processing and found the following:
Code:
void setup() {
size(200, 200);
background(102);
}
void loop() {
stroke(255);
if(mousePressed && pmouseX != 0 && pmouseY != 0) {
line(mouseX, mouseY, pmouseX, pmouseY);
}
}
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this is a simple drawing-programm. what i don't understand is, why the if-brackets contain the conditions: pmouseX and pmouseY. It does not make sense to me. either i am in the field or i am out of the field. and 0 is in the field, am i right. so why shouldn't the pmouse-Value != 0?
Can you follow me?
i changed the code, just erasing the pmouse-conditions and the programm worked as good as before.
maybe you can help me to understand?
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Bernd Salewski
student of digital media
Hochschule Bremen
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kevin
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Re: question on an example-program
« Reply #1 on: Dec 26th, 2003, 10:33pm » |
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Hi,
I'm not 100% sure on this, but I expect that it's to save processing power.
e.g. if the position is registered as 0, then the mouse is off the screen and there's no need to draw the line?
- Kevin
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arielm
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Re: question on an example-program
« Reply #2 on: Dec 26th, 2003, 10:41pm » |
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i think the reason for this trick is to avoid an unecessary line to be drawn from the top-left corner in case the user is pressing the mouse at startup...
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Ariel Malka | www.chronotext.org
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