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This page provides information on the Ptex Map.
The VRayPtex node allows you to load and use PTex textures wi= th V-Ray. PTex is a mapping system that applies a separate texture to each = face of a subdivision or polygon mesh and therefore requires no UV assignme= nt. A PTex file can store an arbitrary number of textures along with mipmap= s and adjacency data used for filtering across face boundaries. For more in= formation on the PTex concept, see the Not= es section below. See also the tutorials on Rendering PTex Textures from= Mudbox and Rendering Vector Displacement with Object-= Space PTex. The example shown here, has PTex textures for the Dif= fuse and Bump channels of a V-Ray Materia= l.
FileName =E2=80=93 The .ptx fil= e to be used for the texture. Load the .ptex file from the Browse (= ...) button.
Cache size =E2=80=93 The information in a PTex fil= e is compressed for storage. In order to be used, it has to be uncompressed= and stored in the RAM. This parameter controls how much memory (in MB) is = available for the current texture. If the value is large enough for the who= le texture, the information is extracted only once and is stored during the= entire rendering. Otherwise, the information is constantly read from the h= ard drive, extracted, and used when necessary. Low value for this parameter= may cause large PTex files to render slowly.
Filter type =E2=80=93 Specifies the type of filter= ing that is going to be applied to the texture.
Filter width =E2=80=93 Specifies the width of the = filter.
Filter blur =E2=80=93 Applies additional blur to t= he filter.
Filter sharpness =E2=80=93 (Only available when th= e Filter type is Bicubic)<= strong> Controls the amount of sharpening applied by the filt= er.
Interpolation between mipmap levels =E2=80=93 A pt= ex texture may have several mipmap levels which are basically versions of t= he texture at different resolutions. This allows a higher resolution textur= e to be applied to parts of the object closer to the camera and a lower res= olution version to be applied to parts of the object that are far away. Whe= n this option is enabled, V-Ray interpolates between different mipmap level= s to create a smooth seamless texture in the end.
Anisotropic filtering =E2=80=93 Enables anisotropi= c filtering which improves the rendering of textures when viewed at sharp a= ngles.
Reverse vertex order =E2=80=93 A ptex is generated= for a specific mesh. Sometimes the program generating the ptex numbers the= vertices of the mesh in a reverse order. When this happens, the object is = not properly textured and enabling this option fixes the issue.
Auto color channels =E2=80=93 A ptex may have an a= rbitrary number of channels and there is no sure way to determine which cha= nnel contains which information. When this option is enabled, V-Ray tries t= o select the correct channel for Red, Green, and Blue. When this option is = off, the user manually specifies which channel contains which information.<= /p>
Red/Green/Blue channel =E2=80=93 Manually specifie= s the channel numbers for Red, Green, and Blue.
Alpha type =E2=80=93 Specifies the mode in which a= lpha is applied.
Solid =E2=80=93 Ignores all alpha information.
Alpha from textu=
re =E2=80=93 Takes the information for the alpha from the spe=
cified Alpha channel in the texture.
Alpha from luminance =E2=80=93 Takes the alpha information from the Luminance of the RGB=
channels.
Auto alpha channel =E2=80=93 When enabled,&nb= sp;V-Ray automatically selects the alpha channel from the PTex file.
Alpha channel =E2=80=93 Manually specifies which c= hannel from the PTex file is the alpha channel.
The options in this group deal with cases when the texture is animated t= hrough an IFL file.
IFL Start Frame =E2=80=93 Specifies the frame at w= hich the playback of the texture begins.
IFL End Condition =E2=80=93 Specifies what happens= when the final frame of an animated texture is reached.
Loop=
=E2=80=93 Once the final frame is reached, the animation jumps back t=
o the start frame.
Ping-pong =E2=80=93 Once the fi=
nal frame is reached, the animation is played backwards towards the start a=
nd continues looping in a Ping-pong manner.
Hold =
=E2=80=93 The animation stops at the final frame.
IFL Playback Rate =E2=80=93 A coefficient for the = playback rate of the animated texture. It allows you to slow down or speed = up the playback rate of the texture.
Gamma type =E2=80=93 Specifies the gamma of the texture= .
None=
=E2=80=93 The gamma of the texture is considered to be 1.0 =
and no gamma corrections are applied.
Specify =E2=
=80=93 Manually specifies the color space and gamma of the image with the&n=
bsp;color space and gamma value parameter.
3ds Max =E2=80=93 The 3ds Max options for gamma are considered for this imag=
e and the appropriate gamma corrections are applied. If the 3ds Max gamma o=
ptions are disabled, then the gamma settings are still taken from the other=
parameters.
Color space =E2=80=93 Specifies the color space of= the image when the Gamma type is S= pecify or when the 3ds Max global gamma corrections are disab= led:
Linear =E2=80=93 Specifies that the color data in the file is in linear ph=
ysical space and no additional correction is necessary for rendering.Gamma =E2=80=93 Specifies that the color data is gamma-=
encoded in the file; an inverse gamma correction is applied to the color da=
ta to convert it to linear physical space for rendering, based on the =
gamma value.
sRGB =E2=80=93 Specifies that the co=
lor data in the file is encoded in the sRGB color space; the standard inver=
se sRGB correction is applied to the colors to convert them to linear physi=
cal space for rendering. Note that sRGB color space is similar to the gamma=
2.2 color space, but there are slight differences for dark colors.
Gamma value =E2=80=93 Manually specifies the gamma=
of the loaded texture when the Gamma type is Specify and the Color space is Gamma.