TranslucentLine

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208:TranslucentLine (lineid, amount, additive?, moreflags)

Warning: This special is not fully supported by the UDMF map format. Certain parameters, noted below, have been made obsolete by the ability to directly specify properties within the linedef structure. These parameters should be set to 0 when using the UDMF format.

• lineid: Line ID of lines to make translucent (0 for this line). Obsolete in UDMF.
• amount: How translucent the line should be. Ranges from 0 to 255.
• additive?: Whether this translucent line should use additive translucency or not (0 = normal, 1 = additive)
• moreflags: Sets extended lineflags. See Line_SetIdentification for details. Obsolete in UDMF. This parameter only has a function when used directly in a map.

Sets the amount of translucency for all matching lines (including itself). If lineid is 0, it only sets the translucency of the line it is on. Like Line_SetIdentification, this special sets the linedef's id. Amount controls how opaque the line is. 0 is nearly invisible. 255 is opaque. Intermediate values are somewhere in between.

You can also use this special in an ACS script to change the translucency for lines whose ids match lineid.