Started implementing cameras rotating point.

src/cmd/test/main.go

@@ -26,9 +26,8 @@ func NewPlayer() *Player {
 		Sprite: &gx.Sprite{
 			Object: &gx.Object{
 				T: gx.Transform {
-					P: gx.Vector{100, 150},
 					S: gx.Vector{5, 5},
-					RA: gx.Vector{200, 200},
+					RA: gx.Vector{320, 240},
 				},
 			},
 			Image: playerImg,
@@ -38,6 +37,9 @@ func NewPlayer() *Player {
 	}
 }
 
+func (p *Player) Start(e *gx.Engine) {
+}
+
 func (p *Player) Update(e *gx.Engine) error {
 	dt := e.DT()
 	c := e.Camera()
@@ -76,6 +78,18 @@ func (p *Player) Update(e *gx.Engine) error {
 		} else {
 			c.Object.T.S.Y += gx.Pi * p.ScaleSpeed * dt
 		}
+	case ebiten.KeyZ :
+		if e.KeyIsPressed(ebiten.KeyShift) {
+			c.Object.T.RA.X -= gx.Pi * p.MoveSpeed * dt
+		} else {
+			c.Object.T.RA.X += gx.Pi * p.MoveSpeed * dt
+		}
+	case ebiten.KeyX :
+		if e.KeyIsPressed(ebiten.KeyShift) {
+			c.Object.T.RA.Y -= gx.Pi * p.MoveSpeed * dt
+		} else {
+			c.Object.T.RA.Y += gx.Pi * p.MoveSpeed * dt
+		}
 	}}
 
 	return nil

src/gx/camera.go

@@ -18,7 +18,10 @@ const (
 // position, scale and rotation to apply
 // it to the objects to get the real
 // transform to display on the screen.
-func (c *Camera)Matrix(scale bool) Matrix {
+func (c *Camera)RealMatrix(
+	e *Engine,
+	scale bool,
+) Matrix {
 	g := &Matrix{}
 
 	// For rotating around.
@@ -27,12 +30,16 @@ func (c *Camera)Matrix(scale bool) Matrix {
 		c.Object.T.RA.Y,
 	)
 
-	g.Rotate(c.Object.T.R)
-
 	g.Translate(
 		-c.Object.T.P.X,
 		c.Object.T.P.Y,
 	)
+	g.Rotate(-c.Object.T.R)
+
+	g.Translate(
+		c.Object.T.RA.X,
+		-c.Object.T.RA.Y,
+	)
 
 	if scale {
 		g.Scale(

src/gx/main.go

@@ -33,6 +33,10 @@ func (e *Engine) Camera() *Camera {
 	return e.camera
 }
 
+func (e *Engine) SetCamera(c *Camera) {
+	e.camera = c
+}
+
 func (e *Engine) Keys() []Key {
 	return e.keys
 }
@@ -50,7 +54,6 @@ func New(
 			Object: &Object{
 				T: Transform{
 					S: Vector{1, 1},
-					RA: Vector{480, 320},
 				},
 			},
 		},
@@ -121,6 +124,7 @@ func (e *engine) Layout(ow, oh int) (int, int) {
 	if e.wcfg.FixedSize {
 		return e.wcfg.Width, e.wcfg.Height
 	}
+
 	return ow, oh
 }
 

src/gx/sprite.go

@@ -15,10 +15,13 @@ func (s *Sprite) Draw(
 	i *Image,
 ) {
 	op := &ebiten.DrawImageOptions{}
-	m := s.Object.T.Matrix()
+	m := s.Object.T.Matrix(e)
 
 	if e.camera != nil {
-		m.Concat(e.camera.Matrix(true))
+		m.Concat(e.camera.RealMatrix(
+			e,
+			true,
+		))
 	}
 
 	op.GeoM = m

src/gx/transform.go

@@ -25,7 +25,7 @@ func T() Transform {
 
 // Returns the GeoM with corresponding
 // to the transfrom transformation 
-func (t Transform)Matrix() Matrix {
+func (t Transform)Matrix(e *Engine) Matrix {
 	g := &Matrix{}
 
 	g.Scale(t.S.X, t.S.Y)