diff --git a/internal/game/game.go b/internal/game/game.go
index e66c9f0..a0c1bd2 100644
--- a/internal/game/game.go
+++ b/internal/game/game.go
@@ -27,6 +27,7 @@ type Game struct {
 	fbSize itype.Vec2i
 
 	io     imgui.IO
+	gui    guiState
 	paused bool
 }
 
diff --git a/internal/game/imgui.go b/internal/game/imgui.go
new file mode 100644
index 0000000..e7d3603
--- /dev/null
+++ b/internal/game/imgui.go
@@ -0,0 +1,122 @@
+package game
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"runtime"
+
+	"edgaru089.ml/go/gl01/internal/asset"
+	"edgaru089.ml/go/gl01/internal/igwrap"
+	"edgaru089.ml/go/gl01/internal/util/itype"
+	"edgaru089.ml/go/gl01/internal/world"
+	"github.com/go-gl/glfw/v3.3/glfw"
+	"github.com/inkyblackness/imgui-go/v4"
+)
+
+type guiState struct {
+	showLog, showDebugInfo bool
+	logFollow              bool
+
+	loadChunkFile string
+	loadChunkID   [2]int32
+
+	saveChunkFile string
+	saveChunkID   [2]int32
+}
+
+func (g *Game) initImgui(win *glfw.Window) {
+	imgui.CreateContext(nil)
+	g.io = imgui.CurrentIO()
+
+	cfg := imgui.NewFontConfig()
+	cfg.SetOversampleH(1)
+	cfg.SetOversampleV(1)
+	cfg.SetPixelSnapH(true)
+	g.io.Fonts().AddFontFromMemoryTTFV(asset.Unifont, 16, cfg, g.io.Fonts().GlyphRangesChineseFull())
+	igwrap.Init(win)
+
+	g.gui = guiState{
+		showLog:       true,
+		showDebugInfo: false,
+		logFollow:     true,
+		loadChunkFile: "chunk.gob",
+		loadChunkID:   [2]int32{0, 0},
+		saveChunkFile: "chunk.gob",
+		saveChunkID:   [2]int32{0, 0},
+	}
+}
+
+func (g *Game) imgui() {
+
+	if imgui.BeginV("Player", nil, imgui.WindowFlagsAlwaysAutoResize) {
+		pos := g.player.Position()
+		vel := g.player.Speed()
+		imgui.Text(fmt.Sprintf("Pos: (%.5f, %.5f, %.5f), Vel: (%.5f, %.5f, %.5f)", pos[0], pos[1], pos[2], vel[0], vel[1], vel[2]))
+	}
+	imgui.End()
+
+	if imgui.BeginV("Go Runtime", nil, imgui.WindowFlagsAlwaysAutoResize) {
+		imgui.Text(fmt.Sprintf("%s/%s, compiler: %s", runtime.GOOS, runtime.GOARCH, runtime.Compiler))
+		imgui.Text(fmt.Sprintf("NumCPU=%d, NumGOMAXPROCS=%d", runtime.NumCPU(), runtime.GOMAXPROCS(0)))
+		imgui.Text(fmt.Sprintf("NumCgoCalls=%d, NumGoroutine=%d", runtime.NumCgoCall(), runtime.NumGoroutine()))
+		imgui.Spacing()
+		if imgui.ButtonV("!!! PANIC !!!", imgui.Vec2{X: -2, Y: 0}) {
+			panic("Manual Panic")
+		}
+	}
+	imgui.End()
+
+	if igwrap.Begin("Logs", &g.gui.showLog, imgui.WindowFlagsMenuBar) {
+		if imgui.BeginMenuBar() {
+			if imgui.Button("Clear") {
+				logs = ""
+			}
+			if imgui.Button("Add Logs") {
+				for i := 0; i < 8; i++ {
+					log.Print("Added logs")
+				}
+			}
+			imgui.Checkbox("Autoscroll", &g.gui.logFollow)
+			imgui.EndMenuBar()
+		}
+
+		imgui.BeginChildV("LogScroll", imgui.Vec2{}, true, 0)
+		imgui.Text(logs)
+		if g.gui.logFollow && imgui.ScrollY() >= imgui.ScrollMaxY() {
+			imgui.SetScrollHereY(1.0)
+		}
+		imgui.EndChild()
+		imgui.End()
+	}
+
+	if imgui.Begin("Actions") {
+
+		imgui.Text("Chunks")
+		imgui.Separator()
+		imgui.InputText("Load Filename", &g.gui.loadChunkFile)
+		imgui.SliderInt2("Load ID", &g.gui.loadChunkID, -10, 10)
+		if imgui.ButtonV("Load", imgui.Vec2{X: -2, Y: 0}) {
+			c := &world.Chunk{}
+			f, err := os.Open(g.gui.loadChunkFile)
+			if err != nil {
+				log.Print("LoadChunk: ", err)
+			} else {
+				c.LoadFromGobIndexed(f, int(g.gui.loadChunkID[0]), int(g.gui.loadChunkID[1]))
+				g.world.SetChunk(int(g.gui.loadChunkID[0]), int(g.gui.loadChunkID[1]), c)
+			}
+		}
+		imgui.Separator()
+		imgui.InputText("Save Filename", &g.gui.saveChunkFile)
+		imgui.SliderInt2("Save ID", &g.gui.saveChunkID, -10, 10)
+		if imgui.ButtonV("Save", imgui.Vec2{X: -2, Y: 0}) {
+			c := g.world.Chunks[itype.Vec2i{int(g.gui.saveChunkID[0]), int(g.gui.saveChunkID[1])}]
+			f, _ := os.Create(g.gui.saveChunkFile)
+			c.WriteToGob(f)
+			f.Close()
+		}
+		imgui.Separator()
+
+	}
+	imgui.End()
+}
diff --git a/internal/game/logic.go b/internal/game/logic.go
index 0cfb264..a7f7edc 100644
--- a/internal/game/logic.go
+++ b/internal/game/logic.go
@@ -1,14 +1,11 @@
 package game
 
 import (
-	"fmt"
 	"image/color"
 	"log"
 	"os"
-	"runtime"
 	"time"
 
-	"edgaru089.ml/go/gl01/internal/asset"
 	"edgaru089.ml/go/gl01/internal/igwrap"
 	"edgaru089.ml/go/gl01/internal/io"
 	"edgaru089.ml/go/gl01/internal/render"
@@ -23,28 +20,6 @@ import (
 
 var logs string
 
-type actions struct {
-	loadChunkFile string
-	loadChunkID   [2]int32
-
-	saveChunkFile string
-	saveChunkID   [2]int32
-}
-
-var action *actions
-var logFollow *bool
-
-func init() {
-	action = &actions{
-		loadChunkFile: "chunk.gob",
-		loadChunkID:   [2]int32{0, 0},
-		saveChunkFile: "chunk.gob",
-		saveChunkID:   [2]int32{0, 0},
-	}
-	logFollow = new(bool)
-	(*logFollow) = true
-}
-
 type logger struct{}
 
 func (logger) Write(b []byte) (n int, err error) {
@@ -103,15 +78,7 @@ func (g *Game) Init(win *glfw.Window) {
 		panic(err)
 	}
 
-	imgui.CreateContext(nil)
-	g.io = imgui.CurrentIO()
-
-	cfg := imgui.NewFontConfig()
-	cfg.SetOversampleH(1)
-	cfg.SetOversampleV(1)
-	cfg.SetPixelSnapH(true)
-	g.io.Fonts().AddFontFromMemoryTTFV(asset.Unifont, 16, cfg, g.io.Fonts().GlyphRangesChineseFull())
-	igwrap.Init(win)
+	g.initImgui(win)
 
 	win.SetCursorPos(float64(width)/2, float64(height)/2)
 
@@ -249,78 +216,7 @@ func (g *Game) Update(win *glfw.Window, delta time.Duration) {
 		g.player.SetSpeed(itype.Vec3d{})
 	}
 
-	if imgui.BeginV("Player", nil, imgui.WindowFlagsAlwaysAutoResize) {
-		pos := g.player.Position()
-		vel := g.player.Speed()
-		imgui.Text(fmt.Sprintf("Pos: (%.5f, %.5f, %.5f), Vel: (%.5f, %.5f, %.5f)", pos[0], pos[1], pos[2], vel[0], vel[1], vel[2]))
-	}
-	imgui.End()
-
-	if imgui.BeginV("Go Runtime", nil, imgui.WindowFlagsAlwaysAutoResize) {
-		imgui.Text(fmt.Sprintf("%s/%s, compiler: %s", runtime.GOOS, runtime.GOARCH, runtime.Compiler))
-		imgui.Text(fmt.Sprintf("NumCPU=%d, NumGOMAXPROCS=%d", runtime.NumCPU(), runtime.GOMAXPROCS(0)))
-		imgui.Text(fmt.Sprintf("NumCgoCalls=%d, NumGoroutine=%d", runtime.NumCgoCall(), runtime.NumGoroutine()))
-		imgui.Spacing()
-		if imgui.ButtonV("!!! PANIC !!!", imgui.Vec2{X: -2, Y: 0}) {
-			panic("Manual Panic")
-		}
-	}
-	imgui.End()
-
-	if imgui.BeginV("Logs", nil, imgui.WindowFlagsMenuBar) {
-		if imgui.BeginMenuBar() {
-			if imgui.Button("Clear") {
-				logs = ""
-			}
-			if imgui.RadioButton("Follow", *logFollow) {
-				(*logFollow) = !(*logFollow)
-			}
-			imgui.EndMenuBar()
-		}
-
-		var size *float32
-		if size == nil {
-			size = new(float32)
-		}
-		imgui.BeginChildV("LogScroll", imgui.Vec2{}, true, 0)
-		imgui.Text(logs)
-		if (*size) != imgui.ScrollMaxY() && (*logFollow) {
-			imgui.SetScrollY(imgui.ScrollMaxY())
-		}
-		(*size) = imgui.ScrollMaxY()
-		imgui.EndChild()
-	}
-	imgui.End()
-
-	if imgui.Begin("Actions") {
-
-		imgui.Text("Chunks")
-		imgui.Separator()
-		imgui.InputText("Load Filename", &action.loadChunkFile)
-		imgui.SliderInt2("Load ID", &action.loadChunkID, -10, 10)
-		if imgui.ButtonV("Load", imgui.Vec2{X: -2, Y: 0}) {
-			c := &world.Chunk{}
-			f, err := os.Open(action.loadChunkFile)
-			if err != nil {
-				log.Print("LoadChunk: ", err)
-			} else {
-				c.LoadFromGobIndexed(f, int(action.loadChunkID[0]), int(action.loadChunkID[1]))
-				g.world.SetChunk(int(action.loadChunkID[0]), int(action.loadChunkID[1]), c)
-			}
-		}
-		imgui.Separator()
-		imgui.InputText("Save Filename", &action.saveChunkFile)
-		imgui.SliderInt2("Save ID", &action.saveChunkID, -10, 10)
-		if imgui.ButtonV("Save", imgui.Vec2{X: -2, Y: 0}) {
-			c := g.world.Chunks[itype.Vec2i{int(action.saveChunkID[0]), int(action.saveChunkID[1])}]
-			f, _ := os.Create(action.saveChunkFile)
-			c.WriteToGob(f)
-			f.Close()
-		}
-		imgui.Separator()
-
-	}
-	imgui.End()
+	g.imgui()
 }
 
 // Render, called with a OpenGL context, renders the game.
diff --git a/internal/igwrap/color.go b/internal/igwrap/color.go
new file mode 100644
index 0000000..13b433b
--- /dev/null
+++ b/internal/igwrap/color.go
@@ -0,0 +1,13 @@
+package igwrap
+
+import "github.com/inkyblackness/imgui-go/v4"
+
+// Color converts non-premultiplied RGBA color into imgui.Vec4.
+func Color(r, g, b, a uint8) imgui.Vec4 {
+	return imgui.Vec4{
+		X: float32(r) / 255,
+		Y: float32(g) / 255,
+		Z: float32(b) / 255,
+		W: float32(a) / 255,
+	}
+}
diff --git a/internal/igwrap/glyph_ranges.go b/internal/igwrap/glyph_ranges.go
new file mode 100644
index 0000000..0a6438d
--- /dev/null
+++ b/internal/igwrap/glyph_ranges.go
@@ -0,0 +1,24 @@
+package igwrap
+
+import "github.com/inkyblackness/imgui-go/v4"
+
+var glyphRanges imgui.AllocatedGlyphRanges
+
+// GlyphRanges returns a custom-built glyph ranges set.
+//
+// The ImGUI context must be already initialized.
+func GlyphRanges() imgui.GlyphRanges {
+	if glyphRanges.GlyphRanges == 0 {
+		b := &imgui.GlyphRangesBuilder{}
+
+		b.AddExisting(imgui.CurrentIO().Fonts().GlyphRangesChineseFull())
+
+		// Greek
+		b.Add(0x0391, 0x03A1)
+		b.Add(0x03A3, 0x03FF)
+
+		glyphRanges = b.Build()
+	}
+
+	return glyphRanges.GlyphRanges
+}
diff --git a/internal/igwrap/wrap.go b/internal/igwrap/wrap.go
new file mode 100644
index 0000000..24a4286
--- /dev/null
+++ b/internal/igwrap/wrap.go
@@ -0,0 +1,205 @@
+package igwrap
+
+import (
+	"fmt"
+
+	"edgaru089.ml/go/gl01/internal/util/itype"
+	"github.com/inkyblackness/imgui-go/v4"
+)
+
+// MenuItem wraps imgui.MenuItemV to create a
+// easy-to-use and intuitive interface.
+func MenuItem(name, shortcut string, selected *bool, enabled bool) {
+	if imgui.MenuItemV(name, shortcut, *selected, enabled) {
+		(*selected) = !(*selected)
+	}
+}
+
+// Text wraps imgui.Text to create a
+// shortcut for fmt.Sprintf.
+func Text(format string, a ...interface{}) {
+	imgui.Text(fmt.Sprintf(format, a...))
+}
+
+// Begin wraps imgui.BeginV to create a
+// easy-to-use and intuitive interface.
+//
+// You only need to call End() if the function
+// returns true.
+func Begin(id string, open *bool, flags imgui.WindowFlags) bool {
+	// skip if the window is not open
+	if !(*open) {
+		return false
+	}
+
+	ok := imgui.BeginV(id, open, flags)
+	if !ok {
+		imgui.End()
+	}
+	return ok
+}
+
+// Sliderf creates a slider with 1 float32 variable.
+func Sliderf(label string, a *float32, min, max float32) bool {
+	f := *a
+	ok := imgui.SliderFloat(label, &f, min, max)
+	(*a) = f
+	return ok
+}
+
+// Slider2f creates a slider with 2 float32 variables.
+func Slider2f(label string, a, b *float32, min, max float32) bool {
+	f := [2]float32{*a, *b}
+	ok := imgui.SliderFloat2(label, &f, min, max)
+	(*a) = f[0]
+	(*b) = f[1]
+	return ok
+}
+
+// Slider3f creates a slider with 3 float32 variables.
+func Slider3f(label string, a, b, c *float32, min, max float32) bool {
+	f := [3]float32{*a, *b, *c}
+	ok := imgui.SliderFloat3(label, &f, min, max)
+	(*a) = f[0]
+	(*b) = f[1]
+	(*c) = f[2]
+	return ok
+}
+
+// Slider4f creates a slider with 4 float32 variables.
+func Slider4f(label string, a, b, c, d *float32, min, max float32) bool {
+	f := [4]float32{*a, *b, *c, *d}
+	ok := imgui.SliderFloat4(label, &f, min, max)
+	(*a) = f[0]
+	(*b) = f[1]
+	(*c) = f[2]
+	(*d) = f[3]
+	return ok
+}
+
+// Sliderd creates a slider with 1 float64 variable.
+func Sliderd(label string, a *float64, min, max float64) bool {
+	f := float32(*a)
+	ok := imgui.SliderFloat(label, &f, float32(min), float32(max))
+	(*a) = float64(f)
+	return ok
+}
+
+// Slider2d creates a slider with 2 float64 variables.
+func Slider2d(label string, a, b *float64, min, max float64) bool {
+	f := [2]float32{float32(*a), float32(*b)}
+	ok := imgui.SliderFloat2(label, &f, float32(min), float32(max))
+	(*a) = float64(f[0])
+	(*b) = float64(f[1])
+	return ok
+}
+
+// Slider3d creates a slider with 3 float64 variables.
+func Slider3d(label string, a, b, c *float64, min, max float64) bool {
+	f := [3]float32{float32(*a), float32(*b), float32(*c)}
+	ok := imgui.SliderFloat3(label, &f, float32(min), float32(max))
+	(*a) = float64(f[0])
+	(*b) = float64(f[1])
+	(*c) = float64(f[2])
+	return ok
+}
+
+// Slider4d creates a slider with 4 float64 variables.
+func Slider4d(label string, a, b, c, d *float64, min, max float64) bool {
+	f := [4]float32{float32(*a), float32(*b), float32(*c), float32(*d)}
+	ok := imgui.SliderFloat4(label, &f, float32(min), float32(max))
+	(*a) = float64(f[0])
+	(*b) = float64(f[1])
+	(*c) = float64(f[2])
+	(*d) = float64(f[3])
+	return ok
+}
+
+// DragVec2d creates a dragger with a itype.Vec2d.
+func DragVec2d(label string, vec *itype.Vec2d, speed float64) bool {
+	f := [2]float32{float32((*vec)[0]), float32((*vec)[1])}
+	ok := imgui.DragFloat2V(label, &f, float32(speed), 0, 0, "%.3f", imgui.SliderFlagsNoRoundToFormat)
+	(*vec)[0] = float64(f[0])
+	(*vec)[1] = float64(f[1])
+	return ok
+}
+
+// DragVec2dv creates a dragger with two float64s.
+func DragVec2dv(label string, a, b *float64, speed float64) bool {
+	f := [2]float32{float32(*a), float32(*b)}
+	ok := imgui.DragFloat2V(label, &f, float32(speed), 0, 0, "%.3f", imgui.SliderFlagsNoRoundToFormat)
+	(*a) = float64(f[0])
+	(*b) = float64(f[1])
+	return ok
+}
+
+// Dragd creates a dragger with one float64.
+func Dragd(label string, a *float64, speed float64) bool {
+	f := float32(*a)
+	ok := imgui.DragFloatV(label, &f, float32(speed), 0, 0, "%.3f", imgui.SliderFlagsNoRoundToFormat)
+	(*a) = float64(f)
+	return ok
+}
+
+// Checkbox wraps imgui.Checkbox.
+//
+// It returns true when selected.
+func Checkbox(label string, selected bool) bool {
+	imgui.Checkbox(label, &selected)
+	return selected
+}
+
+// DragButtonV wraps imgui.Button to create a button
+// that can be dragged around.
+//
+// The pushid, if not empty, is pushed into the ImGUI stack.
+//
+// It returns the mouse delta, if dragged, in the last frame.
+func DragButtonV(label string, pushid string) (delta itype.Vec2d) {
+	if len(pushid) != 0 {
+		imgui.PushID(pushid)
+		defer imgui.PopID()
+	}
+
+	imgui.Button(label)
+	if imgui.IsItemActive() {
+		d := imgui.CurrentIO().MouseDelta()
+		delta = itype.Vec2d{float64(d.X), float64(d.Y)}
+	}
+	return
+}
+
+// DragButton calls DragButtonV("Drag", pushid) to create a button
+// that can be dragged around.
+//
+// The pushid, if not empty, is pushed into the ImGUI stack.
+//
+// It returns the mouse delta, if dragged, in the last frame.
+func DragButton(pushid string) (delta itype.Vec2d) {
+	return DragButtonV("Drag", pushid)
+}
+
+// DragButtonv wraps DragButton to create a button to be dragged around.
+//
+// The pushid, if not empty, is pushed into the ImGUI stack.
+//
+// It returns whether the values has changed.
+func DragButtonv(pushid string, x, y *float64, speed float64) bool {
+	delta := DragButton(pushid).Multiply(speed)
+	if delta == (itype.Vec2d{}) {
+		return false
+	}
+	(*x) += delta[0]
+	(*y) += delta[1]
+	return true
+}
+
+// InputInt calls imgui.InputInt.
+//
+// It accepts int instead of int32.
+func InputInt(label string, val *int) bool {
+	x := int32(*val)
+	ok := imgui.InputInt(label, &x)
+	(*val) = int(x)
+	return ok
+}
diff --git a/internal/util/itype/vec.go b/internal/util/itype/vec.go
index fd2c6a6..877d340 100644
--- a/internal/util/itype/vec.go
+++ b/internal/util/itype/vec.go
@@ -49,6 +49,33 @@ func (v Vec4i) MultiplyInt(mult int) Vec4i {
 // Vec2f is a two-element float vector
 type Vec2f [2]float32
 
+func (v Vec2f) Add(add Vec2f) Vec2f {
+	return Vec2f{v[0] + add[0], v[1] + add[1]}
+}
+
+func (v Vec2f) Addv(x, y float32) Vec2f {
+	return Vec2f{v[0] + x, v[1] + y}
+}
+
+func (v Vec2f) Floor() Vec2i {
+	return Vec2i{
+		int(math.Floor(float64(v[0]))),
+		int(math.Floor(float64(v[1]))),
+	}
+}
+func (v Vec2f) Length() float32 {
+	return float32(math.Sqrt(float64(v[0]*v[0] + v[1]*v[1])))
+}
+
+func (v Vec2f) Normalize() Vec2f {
+	l := v.Length()
+	return Vec2f{v[0] / l, v[1] / l}
+}
+
+func (v Vec2f) ToFloat64() Vec2d {
+	return Vec2d{float64(v[0]), float64(v[1])}
+}
+
 // Vec3f is a three-element float vector
 type Vec3f [3]float32
 
@@ -91,6 +118,37 @@ type Vec4f [4]float32
 // Vec2d is a two-element float64 vector
 type Vec2d [2]float64
 
+func (v Vec2d) Add(add Vec2d) Vec2d {
+	return Vec2d{v[0] + add[0], v[1] + add[1]}
+}
+
+func (v Vec2d) Addv(x, y float64) Vec2d {
+	return Vec2d{v[0] + x, v[1] + y}
+}
+
+func (v Vec2d) Multiply(x float64) Vec2d {
+	return Vec2d{v[0] * x, v[1] * x}
+}
+
+func (v Vec2d) Floor() Vec2i {
+	return Vec2i{
+		int(math.Floor(float64(v[0]))),
+		int(math.Floor(float64(v[1]))),
+	}
+}
+func (v Vec2d) Length() float64 {
+	return math.Sqrt(v[0]*v[0] + v[1]*v[1])
+}
+
+func (v Vec2d) Normalize() Vec2d {
+	l := v.Length()
+	return Vec2d{v[0] / l, v[1] / l}
+}
+
+func (v Vec2d) ToFloat32() Vec2f {
+	return Vec2f{float32(v[0]), float32(v[1])}
+}
+
 // Vec3d is a three-element float64 vector
 type Vec3d [3]float64