How to implement 'scrollRect' in 'starling'?

Haxe
1

In traditional display lists, ‘Sprite’ has a ‘scrollRect attribute’,
It is possible to achieve a parallax effect similar to camera motion, but I found that ‘starling’ does not have the ‘scrollRect attribute’

How should I achieve this effect in ‘Starling’? Thank you

Traditional Display List：



var view:Rectangle = new Rectangle(0, 0, 800, 600);
map.scrollRect = view;


addEventListener(Event.ENTER_FRAME, onFrame);

function onFrame(e:Event):void {
    view.x -= 5;
    map.scrollRect = view;
    
}
2

You could likely accomplish the same effect by nesting sprites.

3

It’s not that simple! So simple, I won’t ask anymore

Never change the display object xy!
The xy of any display object is prohibited from being changed!

4

Have you tried mask’s?

5

I have already tried ‘mask’,
The ‘mask’ xyb changes,
The content will not change, so it cannot be done!

I also tried ‘Matrix’, but it didn’t work,
Matrix "will change the xy of the displayed object,

The ‘scrollRect’ method in traditional display objects,
Neither mask nor matrix can achieve such an effect

Later, I tried ‘RenderTexture’,
It can be done, this is real-time rendering into images,
But the cost was too high, so I didn’t use this method!

6

Recently, I have been studying 2D physics engines, Box2D, and Nape.
These days, I need to implement camera motion in the game because “openfl starling” does not have a camera like other game engines, so to achieve the effect of camera motion in the game, I can only change the xy of the map container

But the specification of the 2D physics engine is that all display objects xy synchronize the xy of 2D physical world objects, so when my map container moves, obstacles and other display objects on the map, including corresponding physical world objects, also need to follow the map and easily move accordingly

If the map container and obstacles or other character animations move, and the corresponding physical world objects do not move along, collision detection and physical effects cannot be achieved. Therefore, my initial idea was that when the map container moves, the obstacles and other display objects on the map move, and the corresponding physical world objects also move along

I think moving all display objects and all physical world objects consumes a lot of performance,
So I was looking for a way to display objects without moving them all along. I found the “scrollRect” method in traditional display lists, which can make the displayed objects on the screen move, but the actual xy of the displayed objects remains the same as before. However, I used “starling” and found that this method was not available, so I came directly to the community to ask a question

7

Actually, my direction was wrong from the beginning.
The correct approach is that the physical world and the display list are independent,
So displaying the motion of the object map camera does not require moving objects in the physical world,
Because the object xy in the physical world is calculated in the physical world, the container xy displaying the list is calculated from the corresponding “parent” origin

That is to say, the movement of the display layer lens does not require the movement of objects in the physical world,
Without anyone to communicate with, I can only practice by myself and get some answers

8

In other words:

And then using the mask to crop that, if necessary, to a windowed area.

9

There’s no need, I think the mask consumption will be very high. Secondly, I can directly move the map container

10

Why do I feel like there aren’t many people using the physics engine? Is it my illusion?

11

Environmental and gravity effects are not hard to code in manually and to be honest, I find it kind of fun to play around with. I’ve never personally felt the need for a physics engine in my projects where such effects were needed.

I have recently dabbled a bit with particles though ( in @Matse’s Massive-Starling library), which may perhaps be the exception.

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