Re: maintaining alpha value for intersecting lines?
Re: maintaining alpha value for intersecting lines?
- Subject: Re: maintaining alpha value for intersecting lines?
- From: Jean Suisse <email@hidden>
- Date: Thu, 13 Sep 2012 17:41:23 +0200
I'm afraid it won't work.
That's the principle of transparency: you can see what's below, tinted by the color of what's on top.
What are you trying to do ? Maybe there's an other way around.
On 13 sept. 2012, at 14:59, Koen van der Drift wrote:
> That would be too bad. But maybe I can use one of the
> NSCompositingOperation constants, I just read about that.
>
> https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/ApplicationKit/Classes/NSImage_Class/Reference/Reference.html#//apple_ref/c/tdef/NSCompositingOperation
>
> I'll try that later.
>
> - Koen.
>
> On Thu, Sep 13, 2012 at 8:51 AM, Jean Suisse <email@hidden> wrote:
>> It is the expected behavior, since the stacking of two partially transparent objects leads to a less transparent set.
>> So I don't know what you want is possible.
>> Are your lines straight ? If so, maybe you could try to draw one of them in two segments, to avoid the intersection (beware of the anti-aliasing).
>>
>> - Jean
>>
>> On 13 sept. 2012, at 14:40, Koen van der Drift wrote:
>>
>>> When I draw two lines using NSBezierPaths, both of which have an alpha
>>> value of let's say 0.5, the alpha value appears to be higher at the
>>> intersection (the color becomes more opaque). Is there a way to
>>> maintain the original alpha value for lines that intersect?
>>>
>>> - Koen.
>>
Jean Suisse
Institut de Chimie Moléculaire de l’Université de Bourgogne
(ICMUB) — UMR 6302
U.F.R. Sciences et Techniques, Bâtiment Mirande
Aile B, bureau 411
9, avenue Alain Savary — B.P. 47870
21078 DIJON CEDEX
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