A question for designers

F

flewpastu

Charter Member
I am currently converting some BMP files to dds, My question is should I convert them to dds DXT1 or 3 or 5.

Thanks In Advance

Bill
 
I use DDS5 since that format is used by FSX, but the other ones seems to work as well. I saved a quality texture I made in all 3 formats with DTXBmp and looked at the quality and file sizes. DDS1 was the smallest size and I could barely notice some degradation of the image. DDS3 and DDS5 same file sizes and I noticed no differecne in image quality.
 
It's explained in the SDK:

"DXT1 DXT1 is recommended if the image in question employs a 1 bit Alpha channel (only Pure Black and Pure White)

DXT3 DXT3 and DXT5 should be used for images which employ 4 or 8 bit Alpha channels (16 or 256 grayscale levels). DXT3 and DXT5 both end up using the same amount of disk space when compressed, however the
DXT5 compression scheme employs a better algorithm to compress the Alpha channel. DXT3 images can include some rather unsightly compression artifacts in the Alpha channel.

DXT5 Use the DXT5 option for any image where the Alpha channels bit depth needs to be 8 bit. "



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I noticed that DXt1 when converted is slightly bigger that the original BMP file and dxt5 is alot bigger than the orginal. Does this effect the fps if the bmp file is lets say 1.00 mgs and then when converted to dds fxt5 its now 1.33 mgs.

Thanks

Bill
 
Those numbers seem off, Bill. Usually, I find that DXT compression results in smaller files, not larger ones. Had the BMP files already been downsampled to 8-bit before you converted them?
 
spotlope said:
Those numbers seem off, Bill. Usually, I find that DXT compression results in smaller files, not larger ones. Had the BMP files already been downsampled to 8-bit before you converted them?
Click to expand...

That is what I was thinking also.
 
I did not know that FSX ran DXT1 DDS format... arrghh.. :banghead: Maybe its for scenery? like DXT1 BMP's in FS9?


From what I have learned, DXT5 and DXT 888-8 is for aircraft. 888-8 Is for 32bit High rez of course. DXT5 was my understanding that it was the same as DXT3, that DXT3 was illiminated. But, goes to show you what I know.. Maybe that was early FSX pre-SP1 data.



Bill
 
flewpastu said:
I noticed that DXt1 when converted is slightly bigger that the original BMP file and dxt5 is alot bigger than the orginal. Does this effect the fps if the bmp file is lets say 1.00 mgs and then when converted to dds fxt5 its now 1.33 mgs.

Thanks

Bill
Click to expand...
Then you have added Mipmaps and not converted to DXT1. DXT3/5 has usually 1MB without mipmaps and with mipmaps 1.33MB. DXT1 with and without mipmaps should be much less.

I convert the most of my AI and VC textures to DXT1 when they don't have an alpha channel. That reduces the texture size dramatically which is very important for AI aircraft.
It's also recommendable to add Mipmaps to your AI and scenerie textures (but not to normal maps).
There is no restriction to use DXT1 only for sceneries:isadizzy: That's maybe in X-Plane...
 
An aircraft should have the texture format in the mdl. I tried to change the 32 bit BMP's in the L-4 to DXT5 DDR and they slowed down loading. I placed the larger BMP back in and they loaded faster, not fast enough but faster. I got to build another system .. this one is just too far behind.
 
JoeW said:
An aircraft should have the texture format in the mdl. I tried to change the 32 bit BMP's in the L-4 to DXT5 DDR and they slowed down loading. I placed the larger BMP back in and they loaded faster, not fast enough but faster. I got to build another system .. this one is just too far behind.
Click to expand...


Thats wild to hear Joe. Good to hear as well. If FSX can run high rez faster, thats a good thing... :d



Bill
 
I usually save them first as DXT3 so I can use them in FS9. The I run those DXT3 files through
Imagetool to create the DDS versions for FSX. So far has worked like a charm for me.
:ernae:
 
Lionheart said:
I did not know that FSX ran DXT1 DDS format... arrghh.. :banghead: Maybe its for scenery? like DXT1 BMP's in FS9?
Click to expand...

Bill, I posted at FFDS nearly two years ago what formats to use in FSX:

DDS/DXT1 for all textures that either have no Alpha, or only need a single bit Alpha.

DDS/DXT5
-or-
DDS/888-8

for everything else
 
n4gix said:
Bill, I posted at FFDS nearly two years ago what formats to use in FSX:

DDS/DXT1 for all textures that either have no Alpha, or only need a single bit Alpha.

DDS/DXT5
-or-
DDS/888-8

for everything else
Click to expand...

I must have missed that one Bill.

:ernae:

Probably to busy doing this...... ----> :typing: <--- Gmax


Bill
 
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