Timeline for Why does using additive blending with a linear colour dropoff result in dark fringes?
Current License: CC BY-SA 4.0
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| Oct 11, 2020 at 7:58 | history | edited | user82991 | CC BY-SA 4.0 |
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| Oct 9, 2020 at 21:20 | history | edited | user82991 | CC BY-SA 4.0 |
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| Oct 9, 2020 at 21:13 | history | edited | user82991 | CC BY-SA 4.0 |
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| Oct 9, 2020 at 15:22 | history | edited | user82991 | CC BY-SA 4.0 |
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| Oct 9, 2020 at 14:57 | history | edited | user82991 | CC BY-SA 4.0 |
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| Oct 4, 2020 at 11:03 | comment | added | Nick is tired | Hopefully this image explains why I don't think transparency is related: i.sstatic.net/1cxS6.png, layer 1 and layer 2 are both solid black, each with a circle drawn on them, when the layers are drawn together in additive mode, we still see those dark edges. In addition, all of the drawings I've shown in my post are on a single layer, this image is the first I've used layers in this post. | |
| Oct 4, 2020 at 10:51 | comment | added | Nick is tired |
100% opaque pixels, a brightess for a pixel is calculated based on distance from lamp (ranging from 0 to 1), and then the resulting colour of a pixel is found by multiplying the red green and blue components of the lamp colour by that brightness (rgb(lamp.r * brightness,lamp.g * brightness,lamp.b * brightness)). This is done for each pixel for each lamp and then all of the values are added together.
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| Oct 4, 2020 at 10:48 | comment | added | user82991 | How the color of the edge pixels is calculated in your system? Is there some internal anti-aliasing system in use? Or is everything which is painted 100% opaque pixels? | |
| Oct 4, 2020 at 10:41 | comment | added | Nick is tired | You're right in that that is how it functions in Krita, Krita was only intended as a demonstration of how it can be reproduced, although that does appear to have come back to haunt me. The first screenshot in my post is from my tool which has no transparency support yet produces the same effect. | |
| Oct 4, 2020 at 10:24 | comment | added | user82991 | So, you think there's no transparency in your brush strokes? Right? Check it by painting with brush blending mode = Normal into a blank layer which has blending mode = Normal. Have a white background layer. If your smooth brush really makes a gradient from bright color to black your painted stroke should have black edge. If there's a black edge my answer is a piece of guessed crap which should be deleted immediately. | |
| Oct 4, 2020 at 10:22 | history | edited | user82991 | CC BY-SA 4.0 |
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| Oct 4, 2020 at 10:06 | comment | added | Nick is tired | The colours that I'm dealing with in the tool I'm writing are RGB only, 50% across a gradient from #FFFFFF to #000000 would be #808080, adding these would be #FFFFFF (after accounting for clamping to the range, as, of course, white is as bright as it gets). It's not clear to me from this where transparency comes into it. | |
| Oct 4, 2020 at 9:33 | history | edited | user82991 | CC BY-SA 4.0 |
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| Oct 4, 2020 at 9:11 | history | answered | user82991 | CC BY-SA 4.0 |
