Canvas

The Canvas entity does not render anything, but just contains different data for the OrthogaphicRenderSystem to render. This includes information such as Mesh vertices/indices, the size of the canvas, its children, and how many submeshes the Canvas has.

Canvas Rescaling

When the Screen Resolution does not match the Canvas' dimension, the CanvasScaleSystem kicks in to tell the canvas to rescale itself. This ensures that all positions are correct and scaled to their correct size and any additional work, such as rebuilding the canvas uses the complete and known data during mesh generation.