How to draw a circle?

[Ramblurr]

This isn't a bug. I'm trying to wrap my mind around webgl and play-cljc.

After rendering a few rectangles and triangles I'd thought I'd try to make a circle.

Reading up on how to do this most guides (example) recommend using the TRIANGLE_FAN primitive.

But it seems c/render is hard coded to use the TRIANGLES primitive

play-cljc/src/play_cljc/gl/core.cljc

Lines 341 to 344 in f2ed4eb

	(gl game drawElements (gl game TRIANGLES) draw-count type 0)
	(if instance-count
	(gl game drawArraysInstanced (gl game TRIANGLES) 0 draw-count instance-count)
	(gl game drawArrays (gl game TRIANGLES) 0 draw-count)))))

Any tips would be appreciated.

[Ramblurr]

I think the solution here is to let the have some sort of :index-mode value in the entity map?

[oakes]

If you wanted to stick with TRIANGLES, I suppose you could just render a rectangle and write a fragment shader that discards pixels outside the radius via something like if (length(position - center) > radius) discard;. But if you want to use TRIANGLE_FAN, you probably need to write your own render function. Should be pretty easy to copy the one from play-cljc and make the necessary changes.

IMO I like the first solution best because you probably will eventually want to do something more complex like render a circle with a texture. That will be easier to do if you're just rendering a rectangle and discarding pixels afterwards.