Overview

The NGLCopying is an extension of Cocoa protocol NSCopying.

It defines two basic copying modes to NinevehGL objects:

• Copy: Makes a new clone, copying all the used memory.
• Copy Instance: Makes a new clone, but clonning just the superficial memory.

All the copying method clone the current state of the object, this include the object’s transformations, properties and everything inside the object. However, just like the professional 3D softwares, NinevehGL gives you a choice to save your work and your application’s memory.

Copy All the used memory is copied and every new change made in one of both object will not affect the other one.

Copy Instance Just the superficial memory is copied, the deep memory, the hard one, is now shared by both object. So changes in the superficial structure are separated, but a change in a deep property will be reflected on the other one.

Each object defines what are its “superficial structure” and its “deep structure”. For example, the NGLMaterial class defines its “superficial structure” is composed by all the scalar values (alpha, ambientColor, diffuseColor, emissiveColor, …) and its “deep structure” is composed by the textures (alphaMap, ambientMap, diffuseMap, …). Similarly, the NGLMesh defines its “superficial structure” as all transformations (position, rotation, scale, …) and its “deep structure” as its mesh’s structure (vertex normals, texcoords, tangent space, …).

So, when you change the deep structure in one of both objects (original or copy) that the change will be reflected in the other one as well. This is very usefull for example when you need to clone a mesh changing its transformations but preserving its mesh’s structure (like cloning an asteroid mesh to create a galaxy, or clonning a drop to create a rain).

This is the diagram of NGLCopying protocol:

                                    _________________
                                   |                 |
                                   |    NGLCopying   |
                                   |_________________|
                                            |
      |-------------------------------------|------------------------------|
      |                  |                  |               |              |
  NGLMaterial        NGLShaders        NGLSurface      NGLObject3D     NGLTexture
      |                  |                  |               | 
      |                  |                  |               |
NGLMaterialMulti  NGLShadersMulti   NGLSurfaceMulti     NGLCamera
                                                            |
                                                         NGLMesh

This is the full table of all “superficial” and “deep” structures:

 _______________________________________________________________________________
|                      |                               |                        |
|                      |      Superficial Structure    |     Deep Structure     |
|----------------------|-------------------------------|------------------------|
|                      |          • Identifier         |                        |
|      NGLMaterial     |       • All scalar values     |  • All texture maps    |
|                      |                               |                        |
|----------------------|-------------------------------|------------------------|
|                      |                               |                        |
|   NGLMaterialMulti   |               -               |  • List of Materials   |
|                      |                               |                        |
|----------------------|-------------------------------|------------------------|
|                      |                               |    • Vertex Shader     |
|      NGLShaders      |          • Identifier         |   • Fragment Shader    |
|                      |                               |      • Variables       |
|----------------------|-------------------------------|------------------------|
|                      |                               |                        |
|    NGLShadersMulti   |               -               |   • List of Shaders    |
|                      |                               |                        |
|----------------------|-------------------------------|------------------------|
|                      |          • Identifier         |                        |
|      NGLSurface      |          • Start data         |            -           |
|                      |          • Length data        |                        |
|----------------------|-------------------------------|------------------------|
|                      |                               |                        |
|    NGLSurfaceMulti   |               -               |   • List of Surfaces   |
|                      |                               |                        |
|----------------------|-------------------------------|------------------------|
|                      |      • Transformations        |                        |
|      NGLObject3D     | • Pivot, bounding box, target |            -           |
|                      |   • Rotation Order and Space  |                        |
|----------------------|-------------------------------|------------------------|
|                      |         • Projection          |                        |
|       NGLCamera      |           • Lenses            |            -           |
|                      |           • Meshes            |                        |
|----------------------|-------------------------------|------------------------|
|                      |                               | • Materials, Surfaces  |
|        NGLMesh       |  • Visibility + NGLObject 3D  |       and Shaders      |
|                      |                               |    • Mesh's arrays     |
|----------------------|-------------------------------|------------------------|
|                      |      • File path and Type     |                        |
|      NGLTexture      |  • Quality, Repeat, Optimize  |       • UIImage        |
|______________________|_______________________________|________________________|