Android Question Coordinates in libgdx.

[Eme Fibonacci]

All the coordinates in libgdx are relative to the "world"? Is there any way to keep objects (eg text) always in the fixed position even if the camera moves? Can anyone talk a bit about what is the resolution and coordinate system in libgdx?

Thank you

 

[wonder]

By default, the coordinates of Textures and TextureRegions are relative to the bottom-left corner of the screen (x:0, y:0).
You can create as many cameras as you want, so you can have, for example, an ActionCam object that moves and an OverlayCam that is kept in a fixed position.

'@LibGDX Render Event

ActionCamera.Update
Batch.ProjectionMatrix = ActionCamera.Combined
Batch.Begin
    'Batch.Draw_GameMap
    'Batch.Draw_GameCharacters
    '...
Batch.End

'OverlayCamera.Update <-- not really necessary if the camera never moves
Batch.ProjectionMatrix = OverlayCamera.Combined
Batch.Begin
    'Batch.Draw_UserInterface
    'Batch.Draw_Text
    '...
Batch.End

 

[Eme Fibonacci]

By default, the coordinates of Textures and TextureRegions are relative to the bottom-left corner of the screen (x:0, y:0).
You can create as many cameras as you want, so you can have, for example, an ActionCam object that moves and an OverlayCam that is kept in a fixed position.

'@LibGDX Render Event

ActionCamera.Update
Batch.ProjectionMatrix = ActionCamera.Combined
Batch.Begin
    'Batch.Draw_GameMap
    'Batch.Draw_GameCharacters
    '...
Batch.End

'OverlayCamera.Update <-- not really necessary if the camera never moves
Batch.ProjectionMatrix = OverlayCamera.Combined
Batch.Begin
    'Batch.Draw_UserInterface
    'Batch.Draw_Text
    '...
Batch.End

Perfect! Thank you.

I already have a tilemap (highway) and a camera that does a vertical scroll.
How could I have a second tilemap (clouds) scrolling has different speed as a parallax effect?

 

[Eme Fibonacci]

The question was incomplete. Would it be better, to create a parallax should I use the same principle or is there a better way?

 

[wonder]

For the parallax effect, you could, for example set the layers in 3D space (x, y, z) and obtain their 2D (x, y) coordinate by dividing by z.
http://anthony.liekens.net/index.php/Computers/RenderingTutorial3DTo2D

That's how I do it, by there are other ways, of course.

 

[sorex]

By default, the coordinates of Textures and TextureRegions are relative to the bottom-left corner of the screen (x:0, y:0).

that's kind of strange. can it be changed to top left ?

 

[Eme Fibonacci]

that's kind of strange. can it be changed to top left ?

I was looking on google about this. It seems that it is possible to flip the axes but maybe it is better to use the standard way.

 

[sorex]

well, that's the point. it's not really standard.

everything I used so far is going from top left to bottom right.

 

[wonder]

that's kind of strange. can it be changed to top left ?

Yes.

Camera.SetToOrtho2(True, lGdx.Graphics.Width, lGdx.Graphics.Height)

Of course, you will then have to flip your texture regions:

myTextureRegion.Flip(False, True) '(x, y)

 

[sorex]

thanks, @wonder. I'll give that a try.

 

[sorex]

the camera part works fine.

but there's no flip method on the lgTexture type.

 

[sorex]

ok, I figured it out.

I had to use

texSmiley.Initialize("smiley.png")
regSmiley.InitializeWithTexture(texSmiley)
regSmiley.Flip(False,True)

and use drawRegion instead of drawText

Batch.DrawRegion(regSmiley,200,50)