Samplers

Compatibility:

• Info: lwks.com starting on page 12.
• Info: lwks.com starting on page 20.
• Linux and Mac: Only one sampler should be created per texture.
• Address Border: Unfortunately, no details are documented yet.
  Quote from jwrl:

  .. it behaves differently in Windows and Linux.

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Sampler settings

• Examples:
  • Create a sampler called “BorderSample” that uses the texture of input “In1”

    sampler BorderSampler = sampler_state
    {
       Texture = <In1>;
       AddressU = Border;
       AddressV = Border;
       MinFilter = Linear;
       MagFilter = Linear;
       MipFilter = Linear;
    };
    

  • Another example with several samplers
• In case the scaling is changed or the texture position is shifted (sampler position is different than the original texture coordinates):
  Please always set AddressU, AddressV, and Filter for each sampler. Otherwise, undefined states can lead to unexpected results.
• If your effect moves the original position of the pixels (eg zooming), then it can happen:
  • That the calculation results in pixel positions outside the source textures
    (outside the normal range from 0 to 1).
    (Behavior can be set with “AddressU” and “AddressV”)
  • That pixel positions have been calculated that are not at the center of a pixel (Wndows). (Behavior adjustable with filter settings)
  • There are several ways the sampler should proceed in these cases (Windows).
• Examples of different Address settings
  The following examples were zoomed out. Note that zooming is not done with the sampler settings, but is programmed in the program part “Shaders”.
  • Border
  • Mirror
  • ClampToEdge
  • Horizontal Border and vertical ClampToEdge
  • Wrap
• Filer
  • MinFilter = Linear (Zoom out)
    MagFilter = Linear (Zoom in)
    This causes the sampler to mix adjacent pixels when looking for a position between the centers of those pixels.
  • MinFilter = Point (Zoom out)
    MagFilter = Point (Zoom in)
    This setting prevents pixel interpolation.
  • MipFilter (It is unclear whether this filter has any function in Lightworks effects)?