In computer graphics several coordinate systems are used, called spaces. Here the conventions Wurfel Engine uses are presented in sorted order.

Not really used in Wurfel Engine as everything is stored in world/game space.

Or called world space. Internal game coordinates with independent X, Y and Z. Coordinate system origin at game world origin with z at the bottom.

The classes Point and Coordinate work in this space.

Isometric projection of the camera is applied: Gamespace Y and Z are projected on a shared axis Y, and Y is shortened by factor of 0.5. Coordinate system origin at game world origin. Usually in game engines the view space origin is in the origin of the camera. In WE this happens in projection space.

y axis faces up

Also called clip space. The view space is transformed to projection space by applying camera specific transformation. The coordinate origin is moved to the camera center (usually done in view space). The zoom/scaling gets applied here.

y axis faces up

The stuff on the screen. Coordinate origin bottom left of window.

y axis faces up

For more information on coordinate systems used in computer graphics read here.