✨ Interactable object!

pkg/internal/land/object.go

@@ -5,6 +5,8 @@ import "github.com/veandco/go-sdl2/sdl"
 type Object interface {
 	Create()
 	Update()
+	AddChild(child Object)
+	GetChildren() []Object
 }
 
 type DrawableObject interface {
@@ -27,3 +29,7 @@ func (p *BaseObject) Update() {
 func (p *BaseObject) AddChild(child Object) {
 	p.Children = append(p.Children, child)
 }
+
+func (p *BaseObject) GetChildren() []Object {
+	return p.Children
+}

pkg/internal/land/object_collision.go

@@ -1,5 +1,15 @@
 package land
 
+type PositionedObject interface {
+	GetPosition() Vector2D
+	GetSize() Vector2D
+}
+
+func IsOverlapWithPoint(obj PositionedObject, point Vector2D) bool {
+	return point.X >= obj.GetPosition().X && point.X <= obj.GetPosition().X+obj.GetSize().X &&
+		point.Y >= obj.GetPosition().Y && point.Y <= obj.GetPosition().Y+obj.GetSize().Y
+}
+
 type CollidableObject interface {
 	GetPosition() Vector2D
 	GetSize() Vector2D

pkg/internal/land/object_interactable.go

@@ -0,0 +1,7 @@
+package land
+
+type InteractableObject interface {
+	GetPosition() Vector2D
+	GetSize() Vector2D
+	OnClick(mousePos Vector2D)
+}

pkg/internal/land/root.go

@@ -35,26 +35,60 @@ func (p *RootObject) RunEventLoop(tickDuration time.Duration) {
 	}
 }
 
+func (p *RootObject) ForEachChildren(cb func(child Object)) {
+	var caller func(current Object)
+
+	caller = func(current Object) {
+		cb(current)
+		for _, child := range current.GetChildren() {
+			caller(child)
+		}
+	}
+
+	caller(p)
+}
+
+func (p *RootObject) HandleUserEvent(event sdl.Event) {
+	switch event := event.(type) {
+	case *sdl.MouseButtonEvent:
+		if event.Type == sdl.MOUSEBUTTONDOWN {
+			x, y := float64(event.X), float64(event.Y)
+			vec := Vector2D{x, y}
+			p.ForEachChildren(func(child Object) {
+				if interChild, ok := child.(InteractableObject); ok {
+					isOverlap := IsOverlapWithPoint(child.(PositionedObject), vec)
+					if isOverlap {
+						interChild.OnClick(vec)
+					}
+				}
+			})
+		}
+	}
+}
+
 func (p *RootObject) Update() {
 	p.BaseObject.Update()
 
 	// Check collision
-	for _, child := range p.Children {
-		for _, other := range p.Children {
+	p.ForEachChildren(func(child Object) {
+		p.ForEachChildren(func(other Object) {
+			if child == other {
+				return
+			}
 			collidableChild, ok := child.(CollidableObject)
 			if !ok {
-				continue
+				return
 			}
 			collidableOther, ok := other.(CollidableObject)
 			if !ok {
-				continue
+				return
 			}
-			if child != other && checkCollisionBetweenObject(collidableChild, collidableOther) {
+			if checkCollisionBetweenObject(collidableChild, collidableOther) {
 				collidableChild.OnCollide(collidableOther)
 				collidableOther.OnCollide(collidableChild)
 			}
-		}
-	}
+		})
+	})
 
 	p.Analyzer.Tick()
 }
@@ -65,11 +99,15 @@ func (p *RootObject) Draw(pen *sdl.Renderer) {
 	pen.Clear()
 
 	// Render each child
-	for _, child := range p.Children {
+	p.ForEachChildren(func(child Object) {
+		if child == p {
+			// Skip the current to prevent infinite drawing
+			return
+		}
 		if drawableChild, ok := child.(DrawableObject); ok {
 			drawableChild.Draw(pen)
 		}
-	}
+	})
 
 	p.Analyzer.Draw()
 }

pkg/internal/land/vector2d.go

@@ -1,9 +1,15 @@
 package land
 
+import "fmt"
+
 type Vector2D struct {
 	X, Y float64
 }
 
+func (p Vector2D) String() string {
+	return fmt.Sprintf("(%.2f, %.2f)", p.X, p.Y)
+}
+
 func (p Vector2D) IsZero() bool {
 	return p.X == 0 && p.Y == 0
 }

pkg/internal/tiles/tile.go

@@ -3,6 +3,7 @@ package tiles
 import (
 	"git.solsynth.dev/highland/codingland/pkg/internal/land"
 	"github.com/veandco/go-sdl2/sdl"
+	"log"
 )
 
 type Tile struct {
@@ -38,3 +39,7 @@ func (p *Tile) GetSize() land.Vector2D {
 
 func (p *Tile) OnCollide(other land.CollidableObject) {
 }
+
+func (p *Tile) OnClick(mousePos land.Vector2D) {
+	log.Printf("user clicked tile: %s", mousePos.String())
+}

pkg/main.go

@@ -44,7 +44,7 @@ func main() {
 		Size:     land.Vector2D{X: 50, Y: 50},
 	})
 	root.AddChild(&tiles.Tile{
-		Position: land.Vector2D{X: 25, Y: 25},
+		Position: land.Vector2D{X: 50, Y: 50},
 		Size:     land.Vector2D{X: 50, Y: 50},
 	})
 
@@ -57,6 +57,8 @@ func main() {
 			switch event.(type) {
 			case *sdl.QuitEvent:
 				running = false
+			case *sdl.MouseButtonEvent:
+				root.HandleUserEvent(event)
 			}
 		}