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Trans
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Overrid es the player's animation transparency parameters for current game tick. Useful for special effects.

Required parameters:
trans = trans_type (string)
trans_type must be one of the following:
default - does nothing
none - disables transparency
add - draws with full additive transparency
addalpha - draws with additive transparency (alpha must be specified)
add1 - draws with additive transparency, with alpha at 256,128
sub - draws with full subtractive transparency

Optional parameters:
alpha = source_alpha, dest_alpha (int, int)
These are the source and destination alpha values for the addalpha
trans type. Valid values are from 0 (low) to 256 (high). If omitted,
defaults to 256,0.

Example:
; Fades the character in, over 256 ticks.
type = Trans
trigger1 = time < 256
trans = add_alpha
alpha = time, 256-time