Differences between 2D and 3D Scenes

Rendering

If you look at how the RectangleEntity is created in the 2D version of 03 Your first Component, there are a few subtle but important differences from the 3D version of the same tutorial. This is how the 2D components map to their 3D equivalents:

• Entity -> MeshComponent
• RectangleGeometryComponent -> CubeGeometryComponent
• GeometrySkin -> ColorMaterialComponent
• Transform2D -> MeshComponent

In the 2D example, the Entity class doesn't actually do anything, it's simply a dressed up ComponentContainer which provides a platform for future extension (should extension be required). The MeshComponent is more specific than that, it's a wrapper for a away3d.entities.Mesh.

The geometry components are very similar in both cases, they simply define a geometry which can be associated with a visual component and rendered.

GeometrySkin and ColorMaterialComponent both provide instructions for how the scene should render the geometry, but a Skin in the 2D system does more than a Material does in the 3D system.

In the 3D scene:

• MeshComponent wraps up a away3d.entities.Mesh
• ColorMaterialComponent wraps up a away3d.materials.ColorMaterial
• CubeGeometryComponent wraps up a away3d.primitives.CubeGeometry
• Renderer3D wraps up an instance of away3d.containers.View3D.

When renderer3D.validateNow() is called, this calls view3d.render(). As all of the CadetEngine objects are simply wrappers for Away3D objects which exist natively within the Away3D scene, Away3D takes care of the rendering internally; the CadetEngine wrapper Components only exist to give the Away3D objects a presence in the CadetEngine scene graph, enabling them to be editable via the CadetEditor.

In the 2D scene:

• GeometrySkin wraps up a starling.display.Shape (from the Starling Graphics Extension)
• RectangleGeometry is a native CadetEngine class with no Starling equivalent.
• Renderer2D wraps up an instance of starling.core.Starling.

In the 3D scene, it's the concept of a Mesh which formalises the relationship between a Geometry, a Transform and a Material into one object. In the 2D scene there's no such concept, so rather than having a hardcoded relationship as per the Mesh, the relationships between these objects happens in a plug-and-play manner via Component.addSiblingReference().