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    Shader aliasing

    SDK Help
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    • H
      Helper
      last edited by

      THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED

      On 08/01/2004 at 18:53, xxxxxxxx wrote:

      User Information:
      Cinema 4D Version:   6.303 
      Platform:   Windows  ;   
      Language(s) :   C.O.F.F.E.E  ;

      ---------
      I am learning about anti-aliasing in COFFEE via the Texturing and Modelling book and sample RenderMan shader.
      I often see a reference to the following:
      /* Estimate the filter width -- i.e. the change from pixel to pixel -- of
      * float and point values.
      */
      #define filterwidth(x)  (abs(Du(x)*du) + abs(Dv(x)*dv))

      How can we obtain the filterwidth for the pixel currently being shaded from the VolumeData object?
      Cheers

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      • H
        Helper
        last edited by

        THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED

        On 09/01/2004 at 13:35, xxxxxxxx wrote:

        Hard to tell without knowing what 'Du(x)' and 'du' are in the code. I don't know anything about RenderMan. Does anyone else know?

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        • H
          Helper
          last edited by

          THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED

          On 09/01/2004 at 15:16, xxxxxxxx wrote:

          du [scalar] - Change in u across element
          du [scalar] - Change in v across element
          dPdu [vector] - Change in position with u
          dPdv [vector] - Change in position with v
          Du(expr) - Compute the parametric derivative of the expression "expr" with respect to the u parameters of the underlying surface
          Dv(expr) - Compute the parametric derivative of the expression "expr" with respect to the v parameters of the underlying surface

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          • H
            Helper
            last edited by

            THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED

            On 10/01/2004 at 00:40, xxxxxxxx wrote:

            I'm not sure what to map that to in the C4D SDK. Perhaps VolumeData::delta could do, if all you want is to avoid aliasing?

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