利用nvidia DDS Utilities - nvDXT進行DDS轉檔

最近嘗試了幾種dds轉檔的方式，用maxScript的缺陷是在於無法產生alpha，用python透過com操作photoshop則是運行耗時、且我找不到dds的save option，利用nvidia DDS Utilities來進行dds轉檔看來是目前最好的方法。

nvidia DDS Utilities是什麼？nvidia的說明是：
included are a set of utilities for manipulating DDS image files, including:
nvDXT, a command-line binary version of the nvDXT library, 
detach, a tool that extracts MIP levels from a DDS file,
stitch, a tool that recombines MIP levels into a single DDS file and
readDXT, which reads compressed images and writes TGA files.
Download DDS Utilities >> http://developer.nvidia.com/legacy-texture-tools

利用nvDXT即可用command-line的方式來輸出.dds檔案，最簡單的命令如下
nvdxt -profile profile -file file -outdir outdir
nvdxt -profile profile -file file -outsamedir
很方便，可以讀取.psd，-file可運用萬用字元，還可指定profile（由photoshop產生）

----------以下是nvDXT本身的說明內容----------
This program
   compresses images
   creates normal maps from color or alpha
   creates DuDv map
   creates cube maps
   writes out .dds file
   does batch processing
   reads .tga, .bmp, .gif, .ppm, .jpg, .tif, .cel, .dds, .png, .psd, .rgb, *.bw and .rgba
   filters MIP maps


Options:
  -profile : Read a profile created from the Photoshop plugin
  -quick : use fast compression method
  -quality_normal : normal quality compression
  -quality_production : production quality compression
  -quality_highest : highest quality compression (this can be very slow)
  -rms_threshold : quality RMS error. Above this, an extensive search is performed.
  -prescale : rescale image to this size first
  -rescale : rescale image to nearest, next highest or next lowest power of two
  -rel_scale : relative scale of original image. 0.5 is half size Default 1.0, 1.0


Optional Filtering for rescaling. Default cube filter:
  -RescalePoint
  -RescaleBox
  -RescaleTriangle
  -RescaleQuadratic
  -RescaleCubic
  -RescaleCatrom
  -RescaleMitchell
  -RescaleGaussian
  -RescaleSinc
  -RescaleBessel
  -RescaleHanning
  -RescaleHamming
  -RescaleBlackman
  -RescaleKaiser

  -clamp : maximum image size. image width and height are clamped
  -clampScale : maximum image size. image width and height are scaled
  -window : window of original window to compress
  -nomipmap : don't generate MIP maps
  -nmips : specify the number of MIP maps to generate
  -rgbe : Image is RGBE format
  -dither : add dithering
  -sharpenMethod : sharpen method MIP maps
    is
        None
        Negative
        Lighter
        Darker
        ContrastMore
        ContrastLess
        Smoothen
        SharpenSoft
        SharpenMedium
        SharpenStrong
        FindEdges
        Contour
        EdgeDetect
        EdgeDetectSoft
        Emboss
        MeanRemoval
        UnSharp
        XSharpen
        Custom
  -pause : wait for keyboard on error
  -flip : flip top to bottom
  -timestamp : Update only changed files
  -list : list of files to convert
  -cubeMap : create cube map .
            Cube faces specified with individual files with -list option
            positive x, negative x, positive y, negative y, positive z, negative z
            Use -output option to specify filename
            Cube faces specified in one file.  Use -file to specify input filename
  -volumeMap : create volume texture.
            Volume slices specified with individual files with -list option
                  Use -output option to specify filename
            Volume specified in one file.  Use -file to specify input filename

  -all : all image files in current directory
  -outdir : output directory
  -deep [directory]: include all subdirectories
  -outsamedir : output directory same as input
  -overwrite : if input is .dds file, overwrite old file
  -forcewrite : write over readonly files
  -file : input file to process. Accepts wild cards
  -output : filename to write to [-outfile can also be specified]
  -append : append this string to output filename


  -8    : compress 8 bit images with this format
  -16 : compress 16 bit images with this format
  -24  : compress 24 bit images with this format
  -32  : compress 32 bit images with this format

  -swapRB : swap rb
  -swapRG : swap rg
  -gamma : gamma correcting during filtering
  -outputScale : scale the output by this (r,g,b,a)
  -outputBias : bias the output by this amount (r,g,b,a)
  -outputWrap : wraps overflow values modulo the output format
  -inputScale : scale the inpput by this (r,g,b,a)
  -inputBias : bias the input by this amount (r,g,b,a)
  -binaryalpha : treat alpha as 0 or 1
  -alpha_threshold : [0-255] alpha reference value
  -alphaborder : border images with alpha = 0
  -alphaborderLeft : border images with alpha (left) = 0
  -alphaborderRight : border images with alpha (right)= 0
  -alphaborderTop : border images with alpha (top) = 0
  -alphaborderBottom : border images with alpha (bottom)= 0
  -fadeamount : percentage to fade each MIP level. Default 15
  -fadecolor : fade map (color, normal or DuDv) over MIP levels
  -fadetocolor : color to fade to
  -custom_fade : set custom fade amount.  n is number number of fade amounts. fadeamount are [0,1]
  -fadealpha : fade alpha over MIP levels
  -fadetoalpha : [0-255] alpha to fade to
  -border : border images with color
  -bordercolor : color for border
  -force4 : force DXT1c to use always four colors
  -weight : Compression weightings for R G and B
  -luminance :  convert color values to luminance for L8 formats
  -greyScale : Convert to grey scale
  -greyScaleWeights : override greyscale conversion weights of (0.3086, 0.6094, 0.0820, 0)
  -brightness : per channel brightness. Default 0.0 usual range [0,1]
  -contrast : per channel contrast. Default 1.0  usual range [0.5, 1.5]

Texture Format  Default DXT3:
  -dxt1c   : DXT1 (color only)
  -dxt1a   : DXT1 (one bit alpha)
  -dxt3    : DXT3
  -dxt5    : DXT5n
  -u1555   : uncompressed 1:5:5:5
  -u4444   : uncompressed 4:4:4:4
  -u565    : uncompressed 5:6:5
  -u8888   : uncompressed 8:8:8:8
  -u888    : uncompressed 0:8:8:8
  -u555    : uncompressed 0:5:5:5
  -p8c     : paletted 8 bit (256 colors)
  -p8a     : paletted 8 bit (256 colors with alpha)
  -p4c     : paletted 4 bit (16 colors)
  -p4a     : paletted 4 bit (16 colors with alpha)
  -a8      : 8 bit alpha channel
  -cxv8u8  : normal map format
  -v8u8    : EMBM format (8, bit two component signed)
  -v16u16  : EMBM format (16 bit, two component signed)
  -A8L8    : 8 bit alpha channel, 8 bit luminance
  -fp32x4  : fp32 four channels (A32B32G32R32F)
  -fp32    : fp32 one channel (R32F)
  -fp16x4  : fp16 four channels (A16B16G16R16F)
  -dxt5nm  : dxt5 style normal map
  -3Dc     : 3DC
  -g16r16  : 16 bit in, two component
  -g16r16f : 16 bit float, two components

Mip Map Filtering Options. Default box filter:
  -Point
  -Box
  -Triangle
  -Quadratic
  -Cubic
  -Catrom
  -Mitchell
  -Gaussian
  -Sinc
  -Bessel
  -Hanning
  -Hamming
  -Blackman
  -Kaiser

***************************
To make a normal or dudv map, specify one of
  -n4 : normal map 4 sample
  -n3x3 : normal map 3x3 filter
  -n5x5 : normal map 5x5 filter
  -n7x7 : normal map 7x7 filter
  -n9x9 : normal map 9x9 filter
  -dudv : DuDv

and source of height info:
  -alpha : alpha channel
  -rgb : average rgb
  -biased : average rgb biased
  -red : red channel
  -green : green channel
  -blue : blue channel
  -max : max of (r,g,b)
  -colorspace : mix of r,g,b
  -norm : normalize mip maps (source is a normal map)
  -toHeight : create a height map (source is a normal map)


Normal/DuDv Map dxt:
  -aheight : store calculated height in alpha field
  -aclear : clear alpha channel
  -awhite : set alpha channel = 1.0
  -scale : scale of height map. Default 1.0
  -wrap : wrap texture around. Default off
  -minz : minimum value for up vector [0-255]. Default 0

***************************
To make a depth sprite, specify:
  -depth

and source of depth info:
  -alpha  : alpha channel
  -rgb    : average rgb (default)
  -red    : red channel
  -green  : green channel
  -blue   : blue channel
  -max    : max of (r,g,b)
  -colorspace : mix of r,g,b

Depth Sprite dxt:
  -aheight : store calculated depth in alpha channel
  -aclear : store 0.0 in alpha channel
  -awhite : store 1.0 in alpha channel
  -scale : scale of depth sprite (default 1.0)
  -alpha_modulate : multiplies color by alpha during filtering
  -pre_modulate : multiplies color by alpha before processing


Examples
  nvdxt -cubeMap -list cubemapfile.lst -output cubemap.dds
  nvdxt -cubeMap -file cubemapfile.tga
  nvdxt -file test.tga -dxt1c
  nvdxt -file *.tga
  nvdxt -file c:\temp\*.tga
  nvdxt -file temp\*.tga
  nvdxt -file height_field_in_alpha.tga -n3x3 -alpha -scale 10 -wrap
  nvdxt -file grey_scale_height_field.tga -n5x5 -rgb -scale 1.3
  nvdxt -file normal_map.tga -norm
  nvdxt -file image.tga -dudv -fade -fadeamount 10
  nvdxt -all -dxt3 -gamma -outdir .\dds_dir -time
  nvdxt -file *.tga -depth -max -scale 0.5

Send comments, bug fixes and feature requests to texturetools@nvidia.com