Fake 2D Sphere Without A Shader

generateSphereVertices.lua

local function insertVertices(vertices, vert, ...)
  if vert then
    table.insert(vertices, vert)
    insertVertices(vertices, ...)
  end
end

local function createSphereVertex(radius, theta, phi, ox, oy)
  local xb = math.cos(phi) * math.cos(theta)
  local yb = math.sin(theta)
  local x, y = radius * xb, radius * yb
  local r = math.min(1, math.sqrt(xb * xb + yb * yb))
  local f = (1 - math.sqrt(1 - r)) / r
  local u = xb * f + ox
  local v = yb * f + oy
  return {x, y, u, v}
end

local function generateSphereVertices(radius, slices, stacks, ox, oy)
  local pi, cos, sin = math.pi, math.cos, math.sin
  local vertices = {}

  for t=1,stacks do
    local s = t - stacks / 2
    local theta1 = (s - 1) / stacks * pi
    local theta2 = s / stacks * pi

    for p=1,slices do
      local phi1 = (p - 1) / slices * pi
      local phi2 = p / slices * pi

      local v1 = createSphereVertex(radius, theta1, phi1, ox, oy)
      local v2 = createSphereVertex(radius, theta1, phi2, ox, oy)
      local v3 = createSphereVertex(radius, theta2, phi2, ox, oy)
      local v4 = createSphereVertex(radius, theta2, phi1, ox, oy)

      if( t == 1 ) then -- top cap
        insertVertices(vertices, v1, v3, v4)
      elseif( t == stacks ) then --end cap
        insertVertices(vertices, v3, v1, v2)
      else
        insertVertices(vertices, v1, v2, v4)
        insertVertices(vertices, v2, v3, v4)
      end
    end
  end

  return vertices
end

main.lua

local RADIUS = 50
local NUM_VERTS = 40

function love.load()
  sphere_mesh = g.newMesh(generateSphereVertices(RADIUS, NUM_VERTS, NUM_VERTS, 0, 0), 'triangles')
  sphere_mesh:setTexture(texture)
end

function love.update(dt)
  local time = love.timer.getTime()
  sphere_mesh:setVertices(generateSphereVertices(RADIUS, NUM_VERTS, NUM_VERTS, time, time / 2))
end

function love.draw()
  g.draw(sphere_mesh, 0, 0)
end