Processing 1.0 - Processing Discourse - How to create a "value ramp" ?

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Index › Programming Questions & Help › Syntax Questions › How to create a "value ramp"

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How to create a "value ramp" ? (Read 321 times)

crasse

How to create a "value ramp" ?
Dec 9^th, 2008, 3:14am

Hi There !

I'm totally new with processing and this is my first try (I just finished on tutorials ^^ ), so my problem maybe very simple, but I'm trying to create a ramp between 2 values. In fact I don't how it's called in processing, I use to work with PureData, and in PureData it's called a ramp :

for example, how to turn a value X into -X within 5 seconds (to make it smoother) ?

I tried something like this :

for(float i=0; i<abs(x);i=i+0.1){
x -= i; }

but it seems that it generate many values at the same times and not create a linear variation from x to -x.

if anyone has an idea, please give me a hand ^^

JohnG

Re: How to create a "value ramp" ?
Reply #1 - Dec 9^th, 2008, 10:52am

It think something like:

Code:

float tmpx=lerp(X,-X,millis()/5000.0);

will give you a linearly changing value from X to -X over 5 seconds from the program starting.

To do it from an arbitrary point in time:

Code:

int startmillis=5000; //5 seconds in, or you could make this the current value of millis() at a keypress.

float tmpx=lerp(X,-X,(millis()-startmillis)/5000.0);

crasse

Re: How to create a "value ramp" ?
Reply #2 - Dec 11^th, 2008, 2:30am

Thanks for your answer

in fact I didn't manage to do it this way, but I get a good result with something like this :

if (x > x_ecran-50){
xv = xv-(4/r);}
if(x < 50){
xv = xv+(4/r);}

(xv is speed value, and r is size value)

cause in fact I was trying to make a smooth speed reversion when my object go outside the screen) so everything is ok ^^

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