Reducing the geometry bandwidth

Generally speaking, if we use more memory to store some geometrical attributes, we can expect a longer rendering time than if we were using less memory. This is true if:

• We do enforce a 4 bytes alignment of the stored geometry channels, for each channel,
• We do use equally fast data formats (in a word: don't use RED::MFT_DOUBLE).

A practical example of this is detailed here: Reducing data memory on the GPU. Using RED::MFT_UBYTE normals instead of RED::MFT_FLOAT normals can significantly improve the rendering speed on large assemblies. First this will improve the scalability of the system (we can load more data); second a given set of data requires less memory to be fetched by the GPU.

Note that depending on the GPU and on the actual performance bottleneck, this may be noticeable or not...A GPU that has no shader processing power may be bound by the size of the programs to process, so the bandwidth saving may remain unseen. Situations may vary a lot depending on the used platform. But generally speaking, reducing the number of geometry channels and the size of these channels set into RED::IMeshShape objects can be beneficial to performances, assuming we enforce proper memory alignment.

Choosing a shading model

A parallel application architecture