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martinlest2

Bitmaps and Alphas and Mips ... What is the truth?

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I haven't understood, I can see now by reading some posts this afternoon, what is required here. Could someone help?

 

First, in FSX.... I understand that bitmaps without active alpha channels can cause stuttering. Is this for scenery and aircraft? Should they also have Mipmaps??

 

In FS9? Is it the same? I thought that bitmaps there needed active alpha channels but should not have mipmaps. The ReadMe in Peter Nyman's DXT3Fixer tool states, however:

 

"This tool fixes the stutters in FS9 caused by dxt3 textures without mipmaps. The fact is that the alpha data is there, but a byte is set wrong...."

 

So if I run this (excellent) tool, should I be getting it to fix missing mipmaps too? In FSX and FS9??

 

Thanks for any explanation that clears this up for me..

 

Martin

 

BTW. I see that it's ten years ago today that I joined AVSIM!! Please somebody send me a cake.....

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One problem I meant to add. Anyone know why when I run DXT3Fixer it immediately hangs ("not responding"). I am trying to run a simulation - haven't done the real fixes this time round.

 

Also, AlphaSearcher gives me dozens and dozens of bmps where it says 'Access is Denied'. The files aren't locked by any other process, so why can't the programme access these particular bitmaps?

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One problem I meant to add. Anyone know why when I run DXT3Fixer it immediately hangs ("not responding"). I am trying to run a simulation - haven't done the real fixes this time round.

 

Ignore the 'not responding' message and let it do its thing. it will eventually close and leave a log file in the directory where the executable is being run.

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Ok, I will; but mips or no mips (etc.)?

Mip everything except user aircraft.

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In both FS9 and FSX, the same? What is the difference in FS9 with and without Mips for aircraft and for scenery?

 

Thanks!

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Mip everything but user aircraft, which can cause blurry textures in Spot Plane view.

 

regards,

Joe

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Thanks. May be some interesting stuff there, even if a lot says it's for FS98/2002. Not sure how this answers whether I should add mips to DXT3 cloud textures though.

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This tool fixes the stutters in FS9 caused by dxt3 textures without mipmaps

 

If that's what it says, then it's a typo from my part. Get the newest version (v2.1), it has a few improvements and clearly states that it fixes files without an active alpha channel.

 

Mipmaps should be used on anything that you will see in the distance, i.e. scenery, airports, clouds, AI aircraft etc...

The planes you're flying do not need mipmaps and especially cockpit textures should not have them, it can cause blurries on the panels.

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OK, thanks. What about DXT3 clouds? Mips?

 

 

Mip everything but user aircraft, which can cause blurry textures in Spot Plane view.

 

regards,

Joe

Martin, do you know what mipmaps are?

 

In case you don't, or for others reading this that don't.

 

Say you have a texture without mips that is 1024 pixels x 1024 pixels.

 

When the sim tries to render that texture on a very small object, say an AI plane far away that only covers a few pixels of your screen, it has to work harder than it should have to, to do so.

 

Mipmaps are smaller versions of a texture, contained within that texture.

 

So a 1024x1024 mipmapped texture will also contain a 512x512 version as well as a 256x256, 128x128, etc.

 

Now when the sim tries to render that AI plane that only covers a few pixels on your screen, it can do so much more efficiently by selecting a smaller mip than the full 1024x1024.

 

This helps performance without losing quality as there is not much detail to see anyway.

 

So, mip everything except user aircraft textures.

 

Why not user aircraft textures? Because the sim isn't perfect and will step down to a smaller mip at a very short viewing distance and the texture will appear blurry.

 

FYI, each step down in mips reduces available pixel counts by 75%.

 

regards,

Joe

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To be frank, I don't know what they are, no, just what they are supposed to do (is that the same?).

 

Will look for version 2... thanks both for the replies and explanations...

 

M

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