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Polymorphism with Linked Lists

tmarques4 · 2011-11-03T15:38:49

I'm testing an implementation which comprises a linked list of objects, each called Geometry, which stores information about vertices, UVcoordinates and normals in a GeometryData array. The problem is that a geometry object can be either one of the primitive types: points, lines, triangles and quads so; in essence, the data structure is a list of objects which contain one of the aforementioned types, not following any precondition to linking objects. The workaround implemented by me for this would have generic pointers and a type variable which specifies what type it is so proper cast is done. struct point{...}; struct line{...}; struct triangle{...}; struct quad{...}; class Geometry { short type; //POINT, LINE, TRIANGLE OR QUAD void *geometryData; //Pointer to structure of type specified. Geometry *next; } Is this a good approach or is there a better one for working with polymorphism, maybe using templates? Appreciate all help given. Best regards!

General and Gameplay Programming Programming

Started by tmarques4 October 26, 2011 07:08 PM

20 comments, last by tmarques4 12 years, 5 months ago

apatriarca

2,365

November 03, 2011 02:00 PM

This may be a useful exercise to learn polymorphism and inheritance, but I think your are designing your application backwards. You are designing a data structure for 3D models without any use case, but this is one of those cases when the data structure may be really different depending on usage. A 3D model data structure for rendering is very different from a data structure for modeling or geometric computations or ... Indeed, 3D models are usually converted to different formats when converted to game assets. You may soon discover that your design is quite bad in basically every use case of a library of that kind.

tmarques4

189

Author

November 03, 2011 03:38 PM

This may be a useful exercise to learn polymorphism and inheritance, but I think your are designing your application backwards. You are designing a data structure for 3D models without any use case, but this is one of those cases when the data structure may be really different depending on usage. A 3D model data structure for rendering is very different from a data structure for modeling or geometric computations or ... Indeed, 3D models are usually converted to different formats when converted to game assets. You may soon discover that your design is quite bad in basically every use case of a library of that kind.

I'll gladly post my work on this data structure regardless of failure or success and share my experiences as to what I think went wrong and what went right.

Tiago.MWeb Developer - Aspiring CG Programmer

Polymorphism with Linked Lists

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Polymorphism with Linked Lists

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