Weird circles in new scenery

[NickB]

I have noticed some weird circular features in various places in a scenery I am creating. It shows up even on where the airport has been flattened as per attached screen capture. It shows motion like a water feature. I'd like to fix that somehow if someone knows what is causing this.

[wickid]

You have some transparency in your texture there. 100% alpha indicates water. So if the really dark spots in your scenery are also represented in the alpha channel of the DDS, water will show up there.

[BOD1]

Ach, I came on this thread thinking we were talking about absolutely different thing, what a desilusion

01_Crop_circles_Swirl[1].jpg

[NickB]

I am only using 24 bit bitmaps, i.e. no alpha channel for water, and using the Landscape Editor to export to DDS. It's got to be some other issue.

[wickid]

When you export from the landscape editor the alpha channel gets added. It is part of the DDS file format so they will have an alpha channel. Black bits in your tiles will also be black in the alpha channel and will get the water effect.

Look a bit further in the landscape manual and use the wateralpha tool to get the alpha channel correct. Page 32

[NickB]

Thanks. I will look into it.
I was pretty sure the Landscape Editor generated DDS dxt1c only, not dxt1a, and that to get the alpha for water you needed to use nvDXT.exe directly and select dxt1a or dxt3 instead of using the Landscape Editor to export to DDS. Why would the Landscape Editor add an alpha channel based on black unless this is a new feature of CLT2 of the landscape Editor ?

[wickid]

Seems the landscape editor exports DXT1 with 1 bit alpha. Don't know why. But that makes very dark pixels black during the compression causing them to have a fully transparent (full black) pixel in the alpha channel causing the water effect... as I said. Using the wateralpha tool with a full white image will cure it

[NickB]

Thanks for taking the time to provide an explanation. I appreciate it.
dxt1a only provides 3 colors and alpha. CLT2 should switch to dxt1c for 4 colors and no alpha instead, given 24 bit color bitmaps.

[wickid]

Yes, I don't use the export function in the landscape editor. I export directly from GIMP. DXT1 with mipmaps if there is no water in the tile (saves diskspace and loading time) and DXT3 with mipmaps if with water.

[NickB]

Well, I created a batch file to split a tile into 16 subtiles and then used nvdxt with -dxt1c and still got circles ???
To be sure, I erased the 16 tiles and ran Condor and as expected I just got black water, and then ran the batch file and ran Condor, and the textures were there, but the problem was not fixed. See attached screenshot.

set sourcebmp=..\..\Terragen\Textures\0208.bmp
set destinationbmp=TEMP\t1033.bmp
set destinationdds=TEMP\t1033.dds
gdal_translate -of BMP -srcwin 1024 2048 1024 1024 %sourcebmp% %destinationbmp%
nvDXT.exe -quality_highest -nmips 11 -Cubic -dxt1c -outdir "TEMP" -file %destinationbmp%
del %destinationbmp%
move %destinationdds% ..\..\..\Textures

[wickid]

Did you try to export directly from Photoshop or Gimp? Not via nvdxt?

[NickB]

After reading the help for nvdxt, I tried adding -force4 to nvdxt, but got the same result.
I need to find a way to check the DDS format structure of one of the files and confirm it is dxt1c with 4 colors, and if so it has to be Condor doing something (?) when it loads a DDS file.
I am not using GIMP.

[NickB]

I had a look at the structure of the DDS files with a HEX editor and found that nvdxt created dxt1 format is 3 colors+alpha regardless of whether you select dxt1a, dxt1c and even with force4. Although it mostly looks like only the three colors are used, It also seems that alpha is turned on sometimes, creating these water circles. Double bugs in nvdxt ! It turns out this has already been seen as a problem, in this post:

viewtopic.php?f=37&t=17703

My solution was to NOT use the Landscape Editor to export DDS, but to split the tiles with a batch file and use nvdxt with -dxt3, and then use a utility to convert from dxt3 to dxt1 and thus reduce the DDS size by 50%. As a bonus there are now 4 colors per 16 pixel block instead of just 3 for better rendering, and no water circles !