Generate a circular mesh.

genMesh.lua

local function genMesh(num_verts, radius)
  local verts = {}
  local interval = math.pi * 2 / num_verts
  for i=1,num_verts do
    local phi = i * interval
    local x = radius * math.cos(phi)
    local y = radius * math.sin(phi)
    local u = (x + radius) / (radius * 2)
    local v = (y + radius) / (radius * 2)
    table.insert(verts, {x, y, u, v})
  end

  return love.graphics.newMesh(verts)
end