when is Camera.contentPosition used?

[wenq1]

I can see that in SHOW_ALL mode of the camera, contentSize is scaled and contentPosition is set. However upon drawing, is contentPosition taken into account?

Say I have a screen (portrait) of 1200x1920, I set targetContentSize to be (600x400), the content is scaled to 1200x800. When drawing, this 1200x800 rectangle should be centered vertically,shouldn't it? I fail to see where in the engine that process this step.

[elnormous]

Content position is set so that you know where the content's left bottom position is in the viewport. It is not being used, because scale modes need only scale factor to be calculated and then applied to the scene.

[wenq1]

So it is the viewport that actually gets centered? I don't see that implemented in the code either ... Maybe I missed it somehow?

[elnormous]

This is the line that creates the scaled orthographic matrix: https://github.com/elnormous/ouzel/blob/master/ouzel/scene/Camera.cpp#L91

[wenq1]

I fully understand this orthographic matrix. However when I use the engine, say with an example device screen size of 1200x1920, and targetContentSize of 600x800, the contentScale is correctly set to 2. But when I try to draw a 600x800 sprite at position (0, 0), it is drawn on the bottom left corner of the device screen. I am expecting it being drawn vertically centered on the screen, WITHOUT manually setting the position, hence the question.

[wenq1]

Device: 1200x1920
+------+
|      |
+------+
+sprite|
|------+
|      |
+------+
     

targetContentSize: 600x800
draw sprite of size (600x800) at (0, 0)

Expected
+------+
|      |
+------+
+sprite|
|------+
|      |
+------+


Actual
+------+
|      |
|      |
|      |
+------+
+sprite|
|------+

[elnormous]

What scale mode are you using? Can you please post your code somewhere?

[wenq1]

nothing special here. Basically it boils down to

        videoLayer = new Layer ()

        videoCamera        = new Camera ('show-all');
        videoCamera.setTargetContentSize (600, 400);
        videoLayer.addCamera (videoCamera);
        addLayer (videoLayer);

        videoSprite    = new Sprite (600, 400);
        videoNode      = new Node ();
        videoNode.setPosition (0, 0);
        videoNode.addComponent (videoSprite);

        videoLayer.addChild (videoNode);

[wenq1]

Ah.. I see. Ouzel has center of the screen as the origin, whereas I'm assuming the bottom-left corner.. How interesting..