Sponza Demo Pt 1 Initial Design

The Sponza model is quite popular for real-time graphics visualisation, It can be downloaded from the CryTek website, and you can see many demos of it being used for different lighting tests on youtube.

I decided it would be a good example to use in a bigger system of how to load and process meshes / textures in OpenGL and also as part of a bigger modelling / game pipeline.

The main model comes in two parts, a wavefront obj file (obj) and a Material template library file (mtl). These files are simple text files and can be exported from all major animation packages.

Initial Design
My initial design for the program is as follows

I will split the Mtl and Obj files into two different classes, the Mtl class will be responsible for loading the textures and storing OpenGL texture ID's. The ObjG (GroupedObj) class will load the Obj and then determine and process the groups in the file and store all the information required to draw all the individual grouped elements.

The mesh itself will be uploaded as a single OpenGL Vertex Array Object (VAO) and elements will be drawn as sub meshes with the correct textures enabled.

I decided to design / write the Mtl class first. This design can be seen in the next post.