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methode to reverse gradient fill (Read 1170 times)

milc

methode to reverse gradient fill
Sep 11^th, 2007, 3:57pm

hi,
I'm afraid that i'm posting a really dumb question, but i've tried to solve the problem alone nearly for an hour, and i get confused more and more, so please help me...

below is the code from Ira Greenberg's book to make a continuous radial gradient;

size(200, 200);
background(0);

for (int i=255; i>0; i--){
noStroke();
fill(255-i);
ellipse(width/2, height/2, i, i);
}

i fully understood how it works, i was very happy about it, and i tried to do some simple modification. Ira's gradient starts from white center and goes darker and darker when expanding to frame. i wanted to make the opposite, darker inside and goes lighter and lighter, i wrote;

size(200, 200);
background(0);

for (int i=0; i<255; i++){
noStroke();
fill(0+i);
ellipse(width/2, height/2, i, i);
}

for me, my code makes sense, but the result is, just big white ellipse.

what did i wrong?? i seriously can not find out what to do beside the code above to reverse the gradient...

thank you.

fjen

Re: methode to reverse gradient fill
Reply #1 - Sep 11^th, 2007, 4:25pm

you are wrong with the assumption that iras code starts from the center. it starts from outside ( black ) and goes to inside ( white ). what happens in your code is that each ellipse is drawn ontop of all others. hence the white ellipse (circle) that remains in the end.

try:

size(200, 200);
background(0);

for (int i=255; i>0; i--){
noStroke();
fill(i);
ellipse(width/2, height/2, i, i);
}

milc

Re: methode to reverse gradient fill
Reply #2 - Sep 11^th, 2007, 6:04pm

thank you very much fjen,
what I missed is that if i draw ellipses from inside, it will be covered by bigger ellipse, because i draw ellipses with fills, not transparent ellipses!!

but it's still surprising that i never arrived to think that i can simply change the order of fill color...i have to open my head and throw my brain out of the window!! how it's useless!

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