fix quat(quat(...)) always returning the identity quaternion under luajit

modules/quat.lua

@@ -67,17 +67,19 @@ function quat.new(x, y, z, w)
 		return new(x, y, z, w)
 
 	-- {x, y, z, w} or {x=x, y=y, z=z, w=w}
-	elseif type(x) == "table" then
+	elseif type(x) == "table" or type (x) == "cdata" then
 		local xx, yy, zz, ww = x.x or x[1], x.y or x[2], x.z or x[3], x.w or x[4]
 		precond.typeof(xx, "number", "new: Wrong argument type for x")
 		precond.typeof(yy, "number", "new: Wrong argument type for y")
 		precond.typeof(zz, "number", "new: Wrong argument type for z")
 		precond.typeof(ww, "number", "new: Wrong argument type for w")
 
 		return new(xx, yy, zz, ww)
-	end
 
-	return new(0, 0, 0, 1)
+	else
+		precond.assert(x == nil, "new: Wrong arguments")
+		return new(0, 0, 0, 1)
+	end
 end
 
 --- Create a quaternion from an angle/axis pair.

spec/quat_spec.lua

@@ -40,6 +40,14 @@ describe("quat:", function()
 		assert.is.equal(1, a.w)
 	end)
 
+	it("creates a quaternion from a quaternion", function()
+		local a = quat (quat(2, 3, 4, 1))
+		assert.is.equal(2, a.x)
+		assert.is.equal(3, a.y)
+		assert.is.equal(4, a.z)
+		assert.is.equal(1, a.w)
+	end)
+
 	it("creates a quaternion from a direction", function()
 		local v = vec3(-80, 80, -80):normalize()
 		local a = quat.from_direction(v, vec3.unit_z)