diff --git a/exp/gamepad/gamepad.go b/exp/gamepad/gamepad.go
new file mode 100644
index 000000000..8f7b7a312
--- /dev/null
+++ b/exp/gamepad/gamepad.go
@@ -0,0 +1,123 @@
+// Copyright 2015 Hajime Hoshi
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package gamepad offers abstract gamepad buttons and configuration.
+package gamepad
+
+import (
+	"github.com/hajimehoshi/ebiten"
+)
+
+// A StdButton represents a standard gamepad button.
+// See also: http://www.w3.org/TR/gamepad/
+//    [UL0]            [UR0]
+//    [UL1]            [UR1]
+//
+//    [LU]     [CC]     [RU]
+//  [LL][LR] [CL][CR] [RL][RR]
+//    [LD]              [RD]
+//         [AL]    [AR]
+type StdButton int
+
+const (
+	StdButtonNone StdButton = iota
+	StdButtonLL
+	StdButtonLR
+	StdButtonLU
+	StdButtonLD
+	StdButtonCL
+	StdButtonCC
+	StdButtonCR
+	StdButtonRL
+	StdButtonRR
+	StdButtonRU
+	StdButtonRD
+	StdButtonUL0
+	StdButtonUL1
+	StdButtonUR0
+	StdButtonUR1
+	StdButtonAL
+	StdButtonAR
+)
+
+const threshold = 0.75
+
+type axis struct {
+	id       int
+	positive bool
+}
+
+type Configuration struct {
+	current StdButton
+	buttons map[StdButton]ebiten.GamepadButton
+	axes    map[StdButton]axis
+}
+
+func (c *Configuration) Scan(index int, b StdButton) bool {
+	if c.buttons == nil {
+		c.buttons = map[StdButton]ebiten.GamepadButton{}
+	}
+	if c.axes == nil {
+		c.axes = map[StdButton]axis{}
+	}
+
+	delete(c.buttons, b)
+	delete(c.axes, b)
+
+	ebn := ebiten.GamepadButton(ebiten.GamepadButtonNum(index))
+	for eb := ebiten.GamepadButton(0); eb < ebn; eb++ {
+		if ebiten.IsGamepadButtonPressed(index, eb) {
+			c.buttons[b] = eb
+			return true
+		}
+	}
+	an := ebiten.GamepadAxisNum(index)
+	for a := 0; a < an; a++ {
+		v := ebiten.GamepadAxis(index, an)
+		// Check v <= 1.0 because there is a bug that a button returns an axis value wrongly and the value may be over 1.
+		if threshold <= v && v <= 1.0 {
+			c.axes[b] = axis{a, true}
+			return true
+		}
+		if -1.0 <= v && v <= -threshold {
+			c.axes[b] = axis{a, false}
+			return true
+		}
+	}
+	return false
+}
+
+func (c *Configuration) IsButtonPressed(id int, b StdButton) bool {
+	if c.buttons == nil {
+		c.buttons = map[StdButton]ebiten.GamepadButton{}
+	}
+	if c.axes == nil {
+		c.axes = map[StdButton]axis{}
+	}
+
+	bb, ok := c.buttons[b]
+	if ok {
+		return ebiten.IsGamepadButtonPressed(0, bb)
+	}
+	a, ok := c.axes[b]
+	if ok {
+		v := ebiten.GamepadAxis(0, a.id)
+		if a.positive {
+			return threshold <= v && v <= 1.0
+		} else {
+			return -1.0 <= v && v <= -threshold
+		}
+	}
+	return false
+}
diff --git a/exp/shape/ellipse.go b/exp/shape/ellipse.go
index 969c7d52e..0a83603e0 100644
--- a/exp/shape/ellipse.go
+++ b/exp/shape/ellipse.go
@@ -60,6 +60,8 @@ func (e *ellipsesLines) Points(i int) (x0, y0, x1, y1 int) {
 	}
 	theta0 = math.Max(theta0, e.angle0)
 	theta1 = math.Min(theta1, e.angle1)
+	theta0 = math.Mod(theta0, 2*math.Pi)
+	theta1 = math.Mod(theta1, 2*math.Pi)
 	fy0, fx0 := math.Sincos(theta0)
 	fy1, fx1 := math.Sincos(theta1)
 	hw, hh := (float64(w)-1)/2, (float64(h)-1)/2