feat: too much to describe.

camera.go

@@ -22,12 +22,11 @@ func (e *Engine) NewCamera() *Camera {
 // position, scale and rotation to apply
 // it to the objects to get the real
 // transform to display on the screen.
-// (Should implement buffering it so we do not
-//  need to calculate it each time for each object. )
 func (c *Camera)RealMatrix() Matrix {
-	/*if c.buf != nil {
+	// Bufferization
+	if c.buf != nil {
 		return *(c.buf)
-	}*/
+	}
 	g := &Matrix{}
 	g.Translate(-c.Position.X, -c.Position.Y)
 	g.Rotate(c.Rotation)

cmd/test/debug.go

@@ -15,21 +15,38 @@ type Debug struct {
 func (d *Debug) Draw(c *Context) {
 	e := c.Engine
 	keyStrs := []string{}
-	for _, k := range e.Keys() {
-		keyStrs = append(keyStrs, k.String())
-	}
 
-	if rectMove.ContainsPoint(e.AbsCursorPosition()) {
+	keys := []string{}
+	for _, k := range e.Keys() {
+		keys = append(keys, k.String())
+	}
+	keyStrs = append(keyStrs, fmt.Sprintf(
+		"keys: %s", strings.Join(keys, ", "),
+	))
+
+	keyStrs = append(keyStrs, fmt.Sprintf(
+		"buttons: %v", c.MouseButtons(),
+	))
+	keyStrs = append(keyStrs, fmt.Sprintf(
+		"wheel: %v", c.Wheel(),
+	))
+
+	/*if rectMove.ContainsPoint(e.AbsCursorPosition()) {
 		keyStrs = append(keyStrs, "contains cursor")
 	}
 
 	if rectMove.Vertices().Contained(rect).Len() > 0 ||
 		rect.Vertices().Contained(rectMove).Len() > 0 {
 		keyStrs = append(keyStrs, "rectangles intersect")
-	}
+	}*/
 
-	keyStrs = append(keyStrs, fmt.Sprintf("%v", e.CursorPosition()))
+	keyStrs = append(keyStrs, fmt.Sprintf(
-	keyStrs = append(keyStrs, fmt.Sprintf("%v", e.AbsCursorPosition()))
+		"camera position: %v %v",
+		c.Camera.Position.X,
+		c.Camera.Position.Y,
+	))
+	keyStrs = append(keyStrs, fmt.Sprintf("realCursorPos: %v", e.CursorPosition()))
+	keyStrs = append(keyStrs, fmt.Sprintf("absCursorPos: %v", e.AbsCursorPosition()))
 	keyStrs = append(keyStrs, fmt.Sprintf("absWinSize: %v", c.AbsWinSize()))
 
 	e.DebugPrint(c.Image,

cmd/test/player.go

@@ -82,9 +82,9 @@ func (p *Player) Update(c *Context) {
 			}
 		case gg.KeyF:
 			if c.IsPressed(gg.KeyShift) {
-				cam.Scale = cam.Scale.Add(gg.V1(p.ScaleSpeed * dt))
+				cam.Scale = cam.Scale.Add(gg.V2(p.ScaleSpeed * dt))
 			} else {
-				cam.Scale = cam.Scale.Add(gg.V1(-p.ScaleSpeed * dt))
+				cam.Scale = cam.Scale.Add(gg.V2(-p.ScaleSpeed * dt))
 			}
 		case gg.KeyG:
 			if c.IsPressed(gg.KeyShift) {
@@ -124,6 +124,17 @@ func (p *Player) Event(c *gg.Context) {
 				p.Layer = HighestL
 			}
 		}
+	case *gg.MouseMove :
+		if !c.IsButtoned(gg.MouseButtonRight) {
+			break
 		}
+		pos := c.Camera.Position
+		c.Camera.Position = pos.Sub(ec.Abs)
+	case *gg.WheelChange :
+		c.Camera.Scale = c.Camera.Scale.Add(gg.V2(
+			ec.Offset.Y * c.DT() * p.ScaleSpeed,
+		))
+	}
+
 }
 

cmd/test/trianlge.go

@@ -11,7 +11,7 @@ type Tri struct {
 func NewTri() *Tri {
 	ret := &Tri{}
 	ret.DrawablePolygon = &gg.DrawablePolygon{}
-	ret.Transform.Scale = gg.V(1, 1)
+	ret.Transform.Scale = gg.V2(1)
 
 	ret.Triangles = gg.Triangles{
 		gg.Triangle{

engine.go

@@ -6,6 +6,7 @@ import (
 	"github.com/di4f/gods/maps"
 	//"fmt"
 	"time"
+	"slices"
 )
 
 // The type represents order of drawing.
@@ -53,8 +54,9 @@ type Engine struct {
 
 	// Temporary stuff 
 	keys, prevKeys []Key
-	cursorPos, prevCursorPos Vector
+	buttons MouseButtonMap
-	mouseButtons, prevMouseButtons []MouseButton
+	wheel Vector
+	cursorPos Vector
 	outerEvents, handleEvents EventChan
 }
 
@@ -65,6 +67,18 @@ func (e *Engine) Keys() []Key {
 	return e.keys
 }
 
+// Returns currently pressed buttons.
+func (e *Engine) MouseButtons() []MouseButton {
+	ret := make([]MouseButton, len(e.buttons))
+	i := 0
+	for v := range e.buttons {
+		ret[i] = v
+		i++
+	}
+	slices.Sort(ret)
+	return ret
+}
+
 // Returns new empty Engine.
 func NewEngine(
 	cfg *WindowConfig,
@@ -79,6 +93,7 @@ func NewEngine(
 	ret.outerEvents = make(EventChan)
 	ret.handleEvents = make(EventChan)
 	ret.Objects = maps.NewOrdered[Object, struct{}]()
+	ret.buttons = MouseButtonMap{}
 	return ret
 }
 
@@ -141,18 +156,94 @@ func (e *Engine) Del(b any) error {
 	return nil
 }
 
+var (
+	allButtons = []MouseButton{
+		MouseButton0,
+		MouseButton1,
+		MouseButton2,
+		MouseButton3,
+		MouseButton4,
+	}
+)
+
+func (e *Engine) IsPressed(k Key) bool {
+	keys := e.Keys()
+	for _, v := range keys {
+		if v == k {
+			return true
+		}
+	}
+
+	return false
+}
+
+func (e *Engine) IsButtoned(b MouseButton) bool {
+	_, ok := e.buttons[b]
+	return ok
+}
+
+func (e *Engine) Wheel() Vector {
+	return e.wheel
+}
+
+func (e *Engine) cursorPosition() Vector {
+	x, y := ebiten.CursorPosition()
+	return V(Float(x), Float(y))
+}
+
+func (e *Engine) CursorPosition() Vector {
+	return e.cursorPos
+}
+
+func (e *Engine) AbsCursorPosition() Vector {
+	m := &Matrix{}
+	m.Concat(e.Camera.AbsMatrix())
+	return e.CursorPosition().Apply(m)
+}
 
 func (e *engine) Update() error {
 	eng := (*Engine)(e)
 
+	e.dt = time.Since(e.lastTime).Seconds()
+	for object := range e.Objects.KeyChan() {
+		updater, ok := object.(Updater)
+		if !ok {
+			continue
+		}
+		updater.Update(&Context{
+			Engine: eng,
+		})
+	}
 	e.prevKeys = e.keys
 	e.keys = inpututil.
 		AppendPressedKeys(e.keys[:0])
 
 	events := []any{}
+	btns := e.buttons
+	for _, btn := range allButtons {
+		if inpututil.IsMouseButtonJustPressed(btn) {
+			btns[btn] = struct{}{}
+			events = append(events, &MouseButtonDown{
+				MouseButton: btn,
+			})
+		} else if inpututil.IsMouseButtonJustReleased(btn) {
+			delete(btns, btn)
+			events = append(events, &MouseButtonUp{
+				MouseButton: btn,
+			})
+		}
+	}
 
-	diff := keyDiff(e.prevKeys, e.keys)
+	x, y := ebiten.Wheel()
-	for _, key := range diff {
+	eng.wheel = V(x, y)
+	if !(eng.wheel.Eq(ZV)) {
+		events = append(events, &WheelChange{
+			Offset: eng.wheel,
+		})
+	}
+
+	keyDiff := diffEm(e.prevKeys, e.keys)
+	for _, key := range keyDiff {
 		var event any
 		if eng.IsPressed(key) {
 			event = &KeyDown{
@@ -166,7 +257,19 @@ func (e *engine) Update() error {
 		events = append(events, event)
 	}
 
-	e.dt = time.Since(e.lastTime).Seconds()
+	realPos := eng.cursorPosition()
+	if !realPos.Eq(eng.cursorPos) {
+		absM := eng.Camera.AbsMatrix()
+
+		absPrevPos :=eng.cursorPos.Apply(&absM)
+		absPos := realPos.Apply(&absM)
+
+		events = append(events, &MouseMove{
+			Real: realPos.Sub(eng.cursorPos),
+			Abs: absPos.Sub(absPrevPos),
+		})
+		eng.cursorPos = realPos
+	}
 	for object := range e.Objects.KeyChan() {
 		eventer, ok := object.(Eventer)
 		if ok {
@@ -177,16 +280,9 @@ func (e *engine) Update() error {
 				})
 			}
 		}
-		updater, ok := object.(Updater)
-		if !ok {
-			continue
 	}
-		updater.Update(&Context{
-			Engine: eng,
-		})
-	}
-	e.lastTime = time.Now()
 
+	e.lastTime = time.Now()
 	return nil
 }
 

event.go

@@ -4,9 +4,9 @@ import (
 	//"github.com/hajimehoshi/ebiten/v2"
 )
 
-func keyDiff(s1, s2 []Key) []Key {
+func diffEm[V comparable](s1, s2 []V) []V {
     combinedSlice := append(s1, s2...)
-    dm := make(map[Key]int)
+    dm := make(map[V]int)
     for _, v := range combinedSlice {
         if _, ok := dm[v]; ok {
             // remove element later as it exist in both slice.
@@ -16,7 +16,7 @@ func keyDiff(s1, s2 []Key) []Key {
         // new entry, add in map!
         dm[v] = 1
     }
-    var retSlice []Key
+    var retSlice []V
     for k, v := range dm {
         if v == 1 {
             retSlice = append(retSlice, k)
@@ -44,7 +44,12 @@ type MouseButtonUp struct {
 }
 
 type MouseMove struct {
-	Delta Vector
+	// Real and absolute deltas.
+	Real, Abs Vector
+}
+
+type WheelChange struct {
+	Offset Vector
 }
 
 type EventChan chan any

keys.go

@@ -156,13 +156,3 @@ const (
 	KeyRightBracket Key = Key(ebiten.KeyBracketRight)
 	KeyArrowUp           Key = Key(ebiten.KeyArrowUp)
 )
-func (e *Engine) IsPressed(k Key) bool {
-	keys := e.Keys()
-	for _, v := range keys {
-		if v == k {
-			return true
-		}
-	}
-
-	return false
-}

mouse.go

@@ -4,16 +4,18 @@ import (
 	"github.com/hajimehoshi/ebiten/v2"
 )
 
+type MouseButtonMap map[MouseButton] struct{}
 type MouseButton = ebiten.MouseButton
+const (
+	MouseButtonLeft   MouseButton = ebiten.MouseButton0
+	MouseButtonMiddle MouseButton = ebiten.MouseButton1
+	MouseButtonRight  MouseButton = ebiten.MouseButton2
 
-func (e *Engine) CursorPosition() Vector {
+	MouseButton0   MouseButton = ebiten.MouseButton0
-	x, y := ebiten.CursorPosition()
+	MouseButton1   MouseButton = ebiten.MouseButton1
-	return V(Float(x), Float(y))
+	MouseButton2   MouseButton = ebiten.MouseButton2
-}
+	MouseButton3   MouseButton = ebiten.MouseButton3
-
+	MouseButton4   MouseButton = ebiten.MouseButton4
-func (e *Engine) AbsCursorPosition() Vector {
+	MouseButtonMax MouseButton = ebiten.MouseButton4
-	m := &Matrix{}
+)
-	m.Concat(e.Camera.AbsMatrix())
-	return e.CursorPosition().Apply(m)
-}
 

transform.go

@@ -22,11 +22,12 @@ type Transform struct {
 	Parent *Transform
 }
 
-// Returns empty Transform
+// Returns the default Transform structure.
-// with standard scaling. (1/1)
 func T() Transform {
 	ret := Transform{
+		// Rotate around
 		Scale: Vector{1, 1},
+		// Rotate around the center.
 		Around: V(.5, .5),
 	}
 	return ret

vector.go

@@ -5,6 +5,10 @@ import (
 	"math"
 )
 
+var (
+	ZV = V2(0)
+)
+
 type Vector struct {
 	X, Y Float
 }
@@ -18,7 +22,7 @@ func V(x, y Float) Vector {
 	return Vector{x, y}
 }
 
-func V1(v Float) Vector {
+func V2(v Float) Vector {
 	return V(v, v)
 }