User:Monster Iestyn/Translucency

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Alpha values

In software mode, SRB2 sometimes has to convert from an 8-bit "alpha" value to an approximate transmap. In OpenGL the reverse often occurs instead.

Translucent FOF alpha to transmap conversion table

Source:

Alpha values Transmap
#000-#011 Invisible
#012-#037 tr_trans90
#038-#063 tr_trans80
#064-#088 tr_trans70
#089-#114 tr_trans60
#115-#139 tr_trans50
#140-#165 tr_trans40
#166-#191 tr_trans30
#192-#216 tr_trans20
#217-#242 tr_trans10
#243-#255 Opaque (turns cyan pixels on flats transparent)

OpenGL transmap to alpha conversion table

Source: HWR_TranstableToAlpha from hw_main.c

Transmap Alpha (Decimal) Alpha (Hexadecimal)
tr_trans10 230 0xe6
tr_trans20 204 0xcc
tr_trans30 179 0xb3
tr_trans40 153 0x99
tr_trans50 128 0x80
tr_trans60 102 0x66
tr_trans70 76 0x4c
tr_trans80 51 0x33
tr_trans90 25 0x19