Performance: Batches v Tris

[rents1977]

My laptop is a bit of a potato, but I noticed batches seem to have more effect than triangles, when looking at the stats shown by pressing F.

E.g. MitCity with 3,000,000 triagles and 300ish batches is more than 3x the speed of the community map with 900,000 triangles and 750+ batches.

What is a batch, and how do I minimise them in my own work?

 

[ohlidalp]

Hi @rents1977 , sorry about the response lag.

Triangle count is a sum of all triangles rendered in the current frame. For performance, it doesn't mean practically anything - even a low tier hardware can process enough of them.

Batch count says how many individual "draw calls" (google that term) must be done to render the scene. For performance, this means everything. 10 individual models with 100 triangles each will render slower than 1 model with 1000 triangles. The basic thing to know is that every individual material needs one draw call - so a model of house with separate roof/walls/windows materials will render slower than a model with single material. Also, each individual 3d model needs one draw call.

EDIT: I just googled a fantastic resource on this: http://simonschreibt.de/gat/renderhell-book1/

 

[rents1977]

@only_a_ptr Thanks for getting back to me, and the link, sorry for my delay in replying. I fall in and out of love with RoR and making maps. I seem to find more problems than I overcome, I want to make larger maps, but a combination of the single page limit, the light map not covering the whole map, exceeding the grass instance limit and LODs not working for me, I can't get a large map in game with the amount of detail I would prefer.

Is it the case that 10 identical models with 100 triangles will also render slower than 1 with 1000? I thought there was a speed benefit from instancing?
If that is the case it might actually make more sense to make e.g. a group of 6 houses as one mesh, rather than 6 meshes? The materials is the big issue. I had been trying to get nice textures by using tiling, I guess lower res texture atlas is better? Also putting 6 houses in one mesh, rather than instances, would allow them to have the AO baked in nicely. Food for thought. Thanks.