[Scummvm-tracker] [ScummVM] #10686: WME: Sprite background is not fully transparent if AlphaColor is set

[lolbot-iichan]

#10686: WME: Sprite background is not fully transparent if AlphaColor is set
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Reporter:  lolbot-iichan  |      Owner:  (none)
    Type:  defect         |     Status:  new
Priority:  normal         |  Component:  Engine: Wintermute
Keywords:                 |       Game:
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 Discovered this issue at FoxTail game, that is using dinamic lighting on
 PNG sprites with transparent background.

 I have exctacted sprite lighting source code and made a simple test game
 to demonstrate this issue without running FoxTail which is not fully
 supported by ScummVM yet:
 https://github.com/tobiatesan/wme_testsuite/tree/master/light_test/packages

 Screenshots are attached. Resulting colot difference is not big (like
 #FFDED5 vs #FFDAD5), however you could see and feel this rectangle moving
 around character sprite both in test game and FoxTail.

 Tested on latest ScummVM from dev branch and ScummVM
 2.1.0git3428-gc518691d7c (Aug 12 2018 19:04:49).

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Ticket URL: <https://bugs.scummvm.org/ticket/10686>
ScummVM <https://bugs.scummvm.org>
ScummVM