Add getRotatedRectBounds helpers

[Geokureli]

Add helpers to FlxRect that calculate the globally-aligned bounding box of a rotated rectangle, and similarly the GABB of a FlxObject and FlxSprite. Useful for determining the actual world space of a rotated rect for things like calculating redraw regions or broad phase collision (like getting a rect quadtree bounds).

I made this when I was looking into issues with pixelPerfectCheck, I thought this might optimize it, preventing it from iterating pixel data when the sprites are far away from each other. that's still in progress, and might not even be fruitful.

I wanted to see if this utility was up to standards, or even worthwhile on its own, before I invested my time into that application of it.

Here's a demo: https://www.newgrounds.com/projects/games/1603054/preview

[Gama11]

Tbh, my first thought is that FlxRect shouldn't know about FlxSprite or FlxObject. :/

[Geokureli]

originally this was in flxCollision. Austin mentioned that people may not look there. i can put them in FlxObject/FlxSprite? or maybe FlxSpriteUtil?

[Geokureli]

converting back to a draft for some drastic changes, namely

• renaming getRotatedRectBounds to calcRotatedBounds since "get" implies simple data retrieval.
• convert the static FlxRect method to an instance method
• finding new places for FlxSprite and FlxObject versions of this.
• unit tests

[Geokureli]

@Gama11 any more thoughts on this?

[Gama11]

Not sure how I feel about a method called calcCollisionBounds() on FlxSprite and FlxObject that respects rotation, considering collisions in Flixel don't respect rotation... So these actually aren't the collision bounds in flixel terms, which could lead to confusion.

In general, I'd be happier with this if they were actually needed for something within flixel, i.e. that optimization you mentioned.

[Geokureli]

I think I already have the optimization in another branch, I can add it here with some performance info.

got anything shorter than calcRotatedCollisionBounds?

[Geokureli]

I've added the optimization to FlxCollision.pixelPerfectCheck

Here is a simple video of the performance difference: https://imgur.com/ISFuHcj
And you can play it yourself here (follow directions in authors comments): https://www.newgrounds.com/projects/games/1574925/preview

The old method checked a bounds much bigger than what was needed. the benefits of this change are bigger as the dimensions of the image increase, especially a long skinny image like the spikes on flappybalt. with the previous method it's bounds were like half the screen even though it's only 9 px wide

I've also renamed calcCollisionBounds to calcRotatedBounds and calcGraphicBounds to calcRotatedGraphicBounds

[Geokureli]

Did some further testing, I didn't realize that pixelPerfectCheck ignores the sprite's scale, when I apply random scaling on the PPC demo's sprites I actually get worse performance because it's checking a larger bounds than it did previously.

it would be neat to honor scale in pixel perfect overlap (it already works with flipX/Y), but for now it may be better to just ignore scale in the bounds check. I may add an arg to calcRotatedGraphicBounds to ignore/allow scale but that seems kinda ugly.

input appreciated

[Geokureli]

Apparently it's pretty easy to get pixelPerfectCheck to work with scale, so I added it. Check it out! Yes, I'm planning many updates to the demo, alongside this.

I renamed calcRotatedGraphicBounds to getScreenBounds to match getScreenPosition. I renamed all the calcRotatedBounds methods back to getRotatedBounds, as well.

[Geokureli]

That's weird. I forgot to update the tests but all tests passed.
Edit: it's probably because I pushed before marking the PR ready

[Geokureli]

Found some other uses and optimizations for this. I also wanted to look into pixelPerfectPosition, pixelPerfectRender and camera zoom to see if those should be considered for these tools

The scope of this change seems to be much bigger than initially thought, if you think it's getting out of hand, let me know

[Geokureli]

in summary this adds:

• FlxRect.getRotatedBounds
• FlxObject.getRotatedBounds
• FlxSprite.getRotatedBounds - override
• FlxSprite.getScreenBounds - similar to FlxSprite.getScreenPosition
• FlxSpriteUtil.cameraWrap - similar to FlxSpriteUtil.screenWrap but uses FlxDirectionFlags instead of 4 booleans
• FlxSpriteUtil.cameraBounds - similar to FlxSpriteUtil.cameraWrap
• FlxCamera.getViewRect - helper for FlxSpriteUtil.cameraWrap and cameraBound
• FlxCamera.containsRect- helper for FlxSpriteUtil.cameraWrap and cameraBound

Made changes to:

• FlxCollision.pixelPerfectCheck - uses getScreenBounds to reduce the number of pixel checks, honors FlxSprite's scale
• FlxSprite.isOnScreen - uses getScreenBounds for more accuracy
• FlxCamera.containsPoint - calls putWeak