Achraf Kassioui AchrafKassioui

Intuitive camera control in SpriteKit

I'm implementing multi-touch camera control in SpriteKit using UIKit gesture recognizers, and I have troubles making pan and rotate work intuitively together.

From a user interface perspective, the goal is:

A pan gesture moves the scene as you'd expect, adjusting for camera rotation.
A pinch gesture scales the scene as you'd expect, with the camera zooming in and out from the midpoint of the gesture, not the view center.
A rotation gesture should rotate the scene as if it were a piece of paper that you manipulate with two fingers. The gesture midpoint at the start of the rotation defines the rotation pivot.

	/**

	# Sprite Motion Blur

	This scene implements per-sprite motion blur with a fragment shader.
	The sprite is larger than the visible shape, so the shader has transparent drawing room around the circle.

	Each fragment samples the sprite texture several times along the current movement direction, then averages those samples into one final color.
	The scene updates the blur direction and length from the sprite physics velocity.

	/**

	# Line Shader

	A minimal setup to start with SpriteKit shaders.

	This setup uses a sprite as a drawing canvas.
	A shader draws a line from point A to point B.
	Touching the scene anywhere updates the point B location and the shader's drawing.

	/**

	# SpriteKit Physics Determinism

	Is SpriteKit's physics engine deterministic?
	In some cases, the physics-based behavior is quite repeatable.
	In other cases, the simulation yields a different outcome every run.

	This is a setup to explore such behaviors.
	Press one of the buttons to play a sequence.

	/**

	Code sample for manual camera setup in SpriteKit.

	Achraf Kassioui
	Created 27 August 2025
	Updated 28 August 2025

	*/
	import SpriteKit

	/**

	# SpriteKit Memory Buildup

	Testing memory build up of a SpriteKit scene when it is presented again and again.

	Achraf Kassioui
	Created 23 November 2024
	Updated 23 November 2024

	/**

	# Investigating SKTileMapNode Memory Leak

	Achraf Kassioui
	Created 22 November 2024
	Updated 22 November 2024

	*/

	/**

	# Testing GKSKNodeComponent

	Apple documentation: https://developer.apple.com/documentation/gameplaykit/gksknodecomponent

	A GKSKNodeComponent is a special class of component that contains a node by default.
	When a GKSKNodeComponent is added to an entity, the `node.entity` property of the node is automatically assigned.
	Whereas if we use a regular GKComponent with a node inside it, we must assign that property manually inside `didAddToEntity` and `willRemoveFromEntity`.
	Note that in both cases, the SpriteKit scene must hold a strong reference to the entity in order to retrieve it.

	/**

	# Physics Joints and Camera

	A scene to investigate how physics joints work across various camera scales.

	Achraf Kassioui
	Created: 28 May 2024
	Updated: 29 May 2024

	/**

	# ChainCIFilter.swift

	In Apple SpriteKit, you can use Core Image filters to add effects to nodes of type `SKEffectNode`, including the scene itself.
	However, the built-in SpriteKit API only takes one filter at a time, and the output can crash SpriteKit's renderer if the result exceeds Metal texture size limit.

	This custom `CIFilter` sub-class provides a solution for both issues:
	- You can run multiple filters on the same effect node.
	- The size of the generated output is checked against a size limit, and is sent to SpriteKit only if the limit is not exceeded.