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Dashed lines at transparent edge of texture


Vulpinus
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A small but irritating problem that's been bugging me, anyone know how to get rid of it? I must be missing something... (like a brain!)

I made a simple privacy screen for my land; some trees with transparency around them so as not to look like a straight wall at the edge.

At the very edge of the screen, if I view from just the right angle (which I seem to do a lot) there appears a dashed vertical line, which moves up/down and the dashes shorten and lenghten as I move my viewpoint about this 'critical angle'. If you've seen it, you'll know exactly what I mean.

The single pixel wide dashed line is the colour of whatever I use for the fill-in in the image where the transparency is (white if I leave it absent).The alpha channel is fully transparent at the edges both sides of the trees; I checked.

If I take an in-world photo, it looks different or does not even show up. The picture below was a screen shot instead.

Changing the texture offset and scaling has no effect on the phenomenon whatsoever. Setting alpha masking (which I use) or alpha blending makes no difference.

The texture is on the inside face of a cut and hollowed cylinder. All other faces are the default transaprent texture.



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Thanks for the reply. I know about that, but I can't get it to work this time.

The cylinder is cut 50% so the single repeat is 2.0. I've tried stepping that down to 1.9 and it makes no difference to this issue at all. I'm not sure it's the same thing that's going on. I've played for hours, changing the scale and twitching the offset, and cannot get rid of that dashed, moving line.

I've realised I see it when looking exactly towards the cut end; as if the viewer is trying to draw a single pxiel thickness at the edge (not the actual thickness of the cylinder)

 

 

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Vulpinus wrote:

The cylinder is cut 50% so the single repeat is 2.0. 
 

Not for the inside surface of a hollow cylinder. For those, the texture repeat depends on the hollow percentage: 95% hollow doubles at about -2.1 whereas 90% hollow doubles at about -2.22. Note that those are negative: inside surfaces are flipped horizontally to match their projection to the outside surface.

Unfortunately none of that is likely to help in this case because you've been tweaking scale and offset plenty already.

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Thanks Que. I think I had figured that out at one point. As you say, it makes no difference anyway. I've tried adjusting the texture all around that range to no effect. This is actually just the latest time that I've revisited this problem; I first made the screen at least six months ago.

I've adjusted the texture so that it ends a little after the end of the object.. So, even if I extended the cut of the cylinder to lengthen it, the texture that would become "visible" would still be transparent. There is nothing anywhere near either end of the object that isn't made transparent by the alpha channel. And yet, the line persists. I've even gone as far as putting my trees in the middle of a double-wide (actually 2.1x) frame, with the rest transparent, so that I can set the repeat at 1.0 and make really sure there is nothing visible near the cut edges of my object. The line persists!

The only way I can minimise the effect to almost gone, but not quite, is to move the texture so that the segment of the cylinder at the end has no visible texture on it. But, I want texture there. If I extend the cut cylinder to the next segment (with no visible texture on it), I still see the line when aligned with the original segment, looking through the transparent next segment.,No difference whatseover. I've manipulating the position and cut of the cylinder, but always get the line back.

As I said previously, it appears as if the viewer is trying to draw the side/edge of the face itself with my texture (not the cylinder, but the surface's face's edge); like looking at the cut edge of a piece of paper. Given that the face has zero thickness, I'm getting the randomly dashed single pixel line that can only be seen when I am in almost perfect alignment with the end of the object, looking into that 'edge'. Unfortunately, the further away from the object, the wider that 'perfect' alignment position becomes.

At this point, I'm pretty sure it's a bug or limitation in the rendering engine.

Oh well, life is too short for things like this. That's why I gave up before. I just try not to stand where I can see it.

If anyone's curious and bored enough to take a look, you are more than welcome to give me a shout in world and I'll give you the screen to play with. Otherwise, I'm giving up again for now.

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