Introduction --- The entity-component architecture is a well known architecture used in many game engines (ECS is more widely used). The motivation behind it is the desire for modularity and extensibility of a scene object interface. The idea is to prefer composition over inheritance for the scene object interface. This allows one to add/remove functionality (components) to an object easily. This also allows things like object morphing as you are not tied to a subclass (ex: a PbdObject can become a FemObject by addition of PbdModel and removal of FemModel). A quick simple psuedo-example for the very unfamiliar (note many ECSs are data oriented and may not have an update, or hybrid and have a subclass that then adds the update): ``` class Component { virtual void update() = 0; } class Object { Component[] components; void update() { for (every comp i in components) { comp.update(); } } } // One should subclass Component to add functionality to Object ``` iMSTK is well suited for this type of architecture due to the large amount of "intra-object customization" required by users. This has been on iMSTK's plate for awhile and it's been lightly moving towards/prepping for it for quite some time now (moving functionality out of the Objects). Example Use Case --- Here's an idea of something that could be possible depending on design: - Ex1: One could construct a ThreadObject which contains PbdModel & AnimatedModel components. Which simulates a line mesh and skins it to a thread geometry. - Ex2: One could construct a SkinObject which contains multiple PbdModel's, VisualModels, & GeometryMap components. - Ex3: One could construct a SkinObject which contains one PbdModel but multiple VisualModels + GeometryMap components. - Ex4: One could construct a all-in-one tool (say arthoscope head) which contains a Camera, Light, RbdModel, & GeometryMap. Possibly even multiple RbdModel's for each piece. Continued details in documents: Documents --- [Notion UML Diagram + Notes](https://www.notion.so/Imstk-ECS-8a00a245e9214ea187d29976e2f02784)