Different aspect ratios in letterbox mode: calculate coords of screen corners?

snooks · August 2017

I am displaying a TileMap on screen and notice that with different aspect ratios than the logical dimensions that there is a bar at the left hand side of the screen. I can manually offset everything to account for this, but would like to calculate what the coordinates are for the bottom left and bottom right corners of the screen in logical pixels at runtime to do this automatically and know what the margins are and exactly what's happening on the user's screen.

I see we have:

ContentWidth
ContentHeight
LogicalWidth
LogicalHeight
DeviceWidth
DeviceHeight
LogicalScaleX
LogicalScaleY

But I'm a bit brain dead at the moment/always so can't see what the relationship is. Could anybody please provide details of how to best deal with this?

Thanks in advance!

totebo · August 2017

You can get the exact X and Y values with these bad boys:

http://docs.giderosmobile.com/reference/gideros/Application/getLogicalTranslateX

http://docs.giderosmobile.com/reference/gideros/Application/getLogicalTranslateY

hgy29 · August 2017

Personnaly I do:

local lox,loy=application:getLogicalTranslateX(),application:getLogicalTranslateY()
local lsx,lsy=application:getLogicalScaleX(),application:getLogicalScaleY()
local cw,ch=application:getContentWidth(),application:getContentHeight()
local scx,scy,scw,sch=-lox/lsx,-loy/lsy,cw+lox/lsx*2,ch+loy/lsy*2

Which gives scx,scy: the screen origin in logical coordinates and scw,sch: the screen size in logical coordinates

antix · August 2017

A tutorial on this stuff would be good, that covers fitting to screen as well

totebo · August 2017

+1 for a tutorial, or even better, a simple project explaining screen resolutions. Gideros is great at it, with @2 and @3 sprites.

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