[Scummvm-tracker] [ScummVM :: Bugs] #15860: ANDROID: Nexus 7 2012 graphics glitch with Larry 6

[ScummVM :: Bugs]

#15860: ANDROID: Nexus 7 2012 graphics glitch with Larry 6
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Reporter:  ebbi2017  |       Owner:  lephilousophe
    Type:  defect    |      Status:  pending
Priority:  normal    |   Component:  Graphics
 Version:            |  Resolution:  fixed
Keywords:            |        Game:  Leisure Suit Larry 6
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Comment (by ebbi2017):

 Thx for the new testbuild. It crashes sadly.

 I also tried this new one, 2.5.1 and 2.9.0 w/ Android developer options
 and forced GPU rendering on and off on each of those, but there's no
 difference whether switching forced GPU on or off.

 Setting "Updates with GPU" (Flash screen when GPU is being used) shows
 that there's no GPU being used in ScummVM on the Nexus 7 2012. Looks like
 it's always rendering in software.
 Only when clicking the 3 stripes top right, the mouse icon left of that
 one has this flash overlay showing it's rendering with GPU when using this
 in Android developer options.
 All other content in ScummVM is CPU rendered it seems. I didn't even set
 CPU rendering in the options. I don't understand it.
 When I switch to other apps like Total Commander the screen flashes way
 more often showing it's GPU rendering when using this developer option
 setting.

 On my Samsung Note 3 (where the games look fine), f.e., ScummVM 2.9.0 and
 developer option to show GPU being used shows a flashing screen in
 ScummVM. When I set software rendering in ScummVM on this device, it keeps
 flashing the screen (GPU rendering). I don't get it.

 These are the specs for Tegra 3:
 https://www.nvidia.com/de-de/drivers/tegra-3/

 OpenGL ES 2.0
 OpenVG    1.1
 EGL       1.4


 Further I found on wikipedia:
 https://en.wikipedia.org/wiki/Nexus_7_(2012)

 "The Tegra 3 processor, besides the four primary cores, features "Variable
 Symmetric Multiprocessing" that uses a fifth "stealth" core designed to
 take over during periods of low processor demand, helping to preserve
 battery life."


 The Nexus 7 2012 uses the Tegra 3 T30L variant (1 out of 5 different Tegra
 3 variants).
 https://en.wikipedia.org/wiki/Tegra#Tegra_3

 So those T30L and maybe other Tegra 3 devices should show pretty the same
 results I guess.
 I don't have any of those, only the Nexus 7 2012 16 GB and another one
 with 32 GB, which shows the same result.

 "T30L   Asus Transformer Pad TF300T, Microsoft Surface, Nexus 7
 (2012),[43] Sony Xperia Tablet S, Acer Iconia Tab A210, Toshiba AT300
 (Excite 10),[44][unreliable source?] BLU Quattro 4.5,[45] Coolpad 9070"



 Could we somehow force OpenGL ES 1.1 for those older ARMHF devices or is
 it too much code for newer ScummVM versions going back to old standards?



 Replying to [comment:13 lephilousophe]:
 > Thank you for the test.
 >
 > To sum it up, the main difference between 2.5.x and now is that we
 switch from OpenGL ES 1.1 to OpenGL ES 2.0.
 > This change brought a new GPU accelerated way to render the 256-color
 games like LSL6.
 >
 > After looking at it more, it seems that the Tegra GPU can't work
 properly with this accelerated rendering as It doesn't provide enough
 precision when accessing the textures.
 >
 > I see no other option than disabling this acceleration of such
 platforms.
 > It's a shame as it seems that only one color was wrong.
 >
 > Could you test this
 [https://drive.google.com/file/d/1m2Agf6K4bnnnA65K5wTg23R1LNUb6Ohc/view?usp=drive_link
 new build] which should switch you back on CPU based rendering for the
 image?
 > I don't expect a measurable performance drawback.
 >
 >
-- 
Ticket URL: <https://bugs.scummvm.org/ticket/15860#comment:14>
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