Culling refers to removing unnecessary stuff based on what’s on screen. If a bullet is not on screen, then it can be deleted. Unless you still need the bullet to exist outside the screen, then it can simply be not drawn. That’s a basic example.

There are 2 culling methods :

• Screen culling : offscreen bullets are culled

• ☄️Distance culling : bullets far away from a Node of Interest have their collision disabled.

  You can define nodes of interest (NoI) by adding them to Spawning.interest_list using .append(Node2D) . When bullets are far away from all of them, their collision will be disabled. When they get closer to any of them, their collision is enabled again. This can be useful when you have large amounts of bullets that can spawn far from the player. The player could not be hit by them, so their collision is useless. You must tweak the different parameters to fit your own game, which requires some trial & error. Tweaking is important because this culling technique requires calculation at every frame so if it’s not usefull to your game, don’t use it or it could worsen performances.

  More info in ☄Disabling Bullet collision when far away from any node of interest

Spawning offers several culling options which are globally active :

• Culling :
  • ☄️Cull margin : bullets are deemed offscreen if their distance to the screen borders (viewport) is farther than this value.
  • ☄️Cull triggers : offscreen bullets won’t trigger their trigger logic
  • ☄️ Technique : determines what happen when a bullet goes offscreen.
    • Anim : this is the minimal behavior, the bullets aren’t drawn anymore but their physics remain the same.
    • Move : offscreen bullets are disabled but not destroyed. Their position will continue being updated except they won’t be rendered and won’t interact with the physical world. If they reenter the screen, they will appear again.
    • Full : offscreen bullets are destroyed right away
    • Inherit : do not pick that. It does nothing.
  • ☄️ Culling rate : delay between 2 culling checks. Checking which bullets are offscreen can be expensive. Instead of doing it every frame (default value), you can choose another delay.
  • ☄️ Increase At : Culling technique goes to Full when this bullet count is reached.
  • ☄️ Max bullets : prevent from spawning new bullets when this number is reached.
  • ☄️ Viewport refresh rate : delay between 2 viewport updates. Checking where are the limits of the screen can be expensive. Instead of doing it every frame (default value), you can choose another delay.
  • ☄️ Fixed screen : if the screen doesn’t move in your game, you can enable this and the viewport will never be updated. You can still update it manually with [☄️**update_viewport()** : update the Rect2() which determines the limits of the screen. Used for Culling. Viewport is updated automatically every Viewport refresh rate times but this function does it manually. It is recommended to call this function every time the scene changes in the scene’s _ready function, before any bullet gets shot.](https://dark-peace.notion.site/update_viewport-update-the-Rect2-which-determines-the-limits-of-the-screen-Used-for-Viewpor-13e6afe4334642fc92e2c51b41ed35a0)
  • ☄️ Culling faking dist : bullets past that distance from ALL NoI in Spawning.interest_list will have their collision disabled.
  • ☄️ Culling unfaking dist : bullets under that distance from ANY NoI will have their collision disabled.
  • 🌀 obsolete features :

<aside> ☄️ As of now, only bullets are affected by culling, not BulletNodes.

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