degenerate triangles

Use indices. Obviously the proper answer is to profile, but the performance difference is probably marginal enough that it's hard to measure, so just use indices because it makes sense.

By using indices you are sending less data through (an index is smaller than a vertex), but more importantly by using an indexed draw you are allowing the GPU to use an optimisation called a post-transform cache. Basically, the quad (012, 213) involves 6 vertices, but the GPU can realise that it can reuse the previous vertex shader output for the second instance of vertices 1 and 2, skipping some work. GPUs don't use a post-transform cache for non-indexed rendering because it'd be too much work to check which vertices are duplicates of earlier ones.

There's a trickier question of whether or not you should use indices as a triangle strip with degenerates (0, 1, 2, 3, 3, 4, 4, 5, 6, 7, 7, etc) or a triangle list (0, 1, 2, 2, 1, 3, 4, 5, 6, 6, 5, 7). It probably makes little difference but I'd choose the latter because there is at least some archaic console hardware that performed particularly badly with degenerates.

Note that rendering a big load of quads is quite common, sometimes it's handy just to make one giant array of indices exactly for that purpose and share it across your 2D system, your particle system, etc.

It shouldn't matter which one you choose, though webGL may be a lot slower so indices might be faster.

but instead use drawArrays with gl_triangels and a degenerate triangle to separate quads.

You would simply just have duplicated vertices where each triangle has 3 unique vertices. The degenerate thing would be if you were drawing indexed vertices using triangle strips/fans where you send -1 I believe as a degenerate index which tells the GPU to draw a brand new polygon that isn't attached to the edges of the previous triangle.

Thanks for your input!

There's a trickier question of whether or not you should use indices as a triangle strip with degenerates (0, 1, 2, 3, 3, 4, 4, 5, 6, 7, 7, etc) or a triangle list (0, 1, 2, 2, 1, 3, 4, 5, 6, 6, 5, 7). It probably makes little difference but I'd choose the latter because there is at least some archaic console hardware that performed particularly badly with degenerates.

It was a typo by me, I meant to say that I am using indices with gl_triangles, not gl_triangle_strips.

Note that rendering a big load of quads is quite common, sometimes it's handy just to make one giant array of indices exactly for that purpose and share it across your 2D system, your particle system, etc.

Yes, I am doing something like this currently, still need to flesh out the architecture.

At the moment, entities (be it particles or something else) is not aware of the rendering system in any way. If they are renderable, they will be rendered.

Sharing the actually index daxa cross components (physics, rendering etc) will make me think about what part of the system should be responsible for the data.

I am still in early stages of development, so I will keep this in consideration moving forward.

Again, thanks for taking you time to answer guys!