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Nina Jashan

Using materials with alpha blending results in blue flicker problems

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When I use Bumpiness and Shininess with alpha blending it has this problem - see image. When I use None or Alpha Masking there's no issue, but I want wings to be slightly transparent and with materials. The issue is also there if if I use any transparency setting.

Capture.PNG 

I'm using Firestorm, but I want to know if this is a known issue with materials and transparency or is it just me.

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The pattern of shading differences you see looks like the sort of effect you get when you get hidden extra materials because you have more than 21844 triangles. So, in case that's the problem, how many triangles do your wings have (per material)? If it's more than 21844, the try reducing it and see if that has any effect.

Of course, it may be something completely different. There were various bad interactions with materials and transparency reprted in the jira, but I haven't kept up with them.

I am assuming your bumpiness is a normal map, not traditional bumpiness. Traditional bumpiness doesn't work with materials.

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 I'm using normals bumpiness, but it seems that even just the shininess alone will cause it, or just the normal without specular - same issue.

My wings are double sided planes that look like this image

 

Wings.png

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Well, certainly not too many triangles there, but then it's hard to understand the tiny fragmentation of effect in the picture you posted before. Any chance you have a sundivision modifier (or equivalent - don't know what software you are using) that comes into effect between this latest picture and the exported mesh?

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Perhaps what you see is the alpha sorting issue? It happens when you you have alpha blending mode on. The only way to avoid it is not to use alpha blending mode.

Like in your wings, you have two (partially) overlapping items. Both have alpha channel in the textures. What happens is that sometimes the wing what is in front indeed shows to be in front. But it also happens that the wing which is behind actually shows to be in front. When this happens in rapid space the result is flickering. In alpha blending OpenGL cannot reliably detect what is in front and what is at the back. Use alpha masking mode and the problem is no more.


I'm not sure if it is alpha sorting issue what you see, but it could be that one.

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Is the pattern fixed, or does it change as you move the wings or camera? If it changes, it's nothing to do with triangles. Does the pattern of patches correspond with some property or colour value of the normal and/or specular maps (including their alpha channels)? (Maybe you can see by applying them as diffuse textures without n&s maps). If so, that might give a clue as to the source of the effect.

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materials issue.PNG

This is another angle so yes it is fixed. My friend sees the wings as perfect. so maybe it's a client side problem, by which I mean something with my graphics or some setting.

I could use alpha masking and all works fine but then my wings aren't slightly transparent. I'm thinking it's just my problem, something local, and others can see the wings just fine with materials and transparency.

I have had the issue before so it isn't just the wings, but always with materials and alpha combination. So I was wondering if it is a known issue or just me - starting to think it's just me.

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Ah. I see that the edges of blockiness are parallel with the frame in either picture although the angle of view is different. So it's nothing to do with the textures themselves or the mesh structure. I think it must indeed be something happening in your graphics card, and the fact that others don't see it suggests the same. Probably you need someone who knows about specific card/driver/settings problems.

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