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Topic: do points have color? (Read 271 times) |
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kevinP
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do points have color?
« on: May 25th, 2004, 6:35pm » |
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Hi all,
I noticed that points will be drawn with the stroke() color, but that alpha is not supported; I also noticed that using noStroke() has no effect on visibility of points.
Is there a reason for this, or is it just that I am doing something strange?
Code:
color cl = color(50, 150, 50, 10);
stroke(cl);
noStroke();
noFill();
for (int i = 15; i < width-15; i++) {
point(i, height/2);
}
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Also here with pixels[], shouldn't I see some transparency from the alpha value?
Code:
color cl = color(250, 150, 50, 10);
stroke(cl);
for (int i = 15; i < width-15; i++) {
point(width/2, i);
}
for (int i=0; i<width*height/2; i++) {
color clr = color(50, 190, 80, 20);
pixels[i] = clr;
}
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-Kevin
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Kevin Pfeiffer
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TomC
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Re: do points have color?
« Reply #1 on: May 25th, 2004, 10:10pm » |
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That is a bit strange about point() - it happens with beginShape(POINTS) too. Not sure why.
If you want alpha points, you can use line(x,y,x,y) instead though:
Code:
color cl = color(50, 150, 50, 10);
stroke(cl);
//noStroke();
noFill();
for (int i = 15; i < width-15; i++) {
line(i, height/2, i, height/2);
}
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Regarding your pixels query, I think pixels[] is the actual array of values which will be written to the screen. So, if a pixel has an alpha value it will be ignored because there isn't a colour to blend it with. The alpha value in BImage.pixels[] will work, of course, so you could write to that and then draw the image on the screen to get the effect you want.
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JohnG
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Re: do points have color?
« Reply #2 on: May 26th, 2004, 12:09pm » |
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pixels[] doesn't support alpha channel, because it contains the value which is actually drawn on the screen, e.g. if you have a white image, then draw a 50% transparent black pixel with set() or similar, the pixels[] value will be 50% grey, not black with 50% transparency.
So if you want to use pixels[] and transparency, you'll have to do the alpha maths yourself.
Or you could just use set(x,y,colour); where colour can include an alpha value, and it'll work it out for you.
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