Implemented better rotating around system.

src/cmd/test/main.go

@@ -68,7 +68,7 @@ func NewPlayer() *Player {
 		Sprite: &gx.Sprite{
 			Transform: gx.Transform {
 				S: gx.Vector{5, 5},
-				RA: gx.Vector{320, 240},
+				RA: gx.Vector{.5, .5},
 			},
 			Visible: true,
 			ShaderOptions: gx.ShaderOptions {
@@ -87,12 +87,12 @@ func NewPlayer() *Player {
 
 func (p *Player) Draw(e *gx.Engine, i *gx.Image) {
 	p.Sprite.Draw(e, i)
+	t := p.Transform
+	t.S.X *= 4.
+	t.S.Y *= 4.
 	r := &gx.DrawableRectangle{
 		Rectangle: gx.Rectangle{
-			Transform: gx.Transform{
-				P: player.P,
-				S: gx.Vector{100, 100},
-			},
+			Transform: t,
 		},
 		Color: gx.Color{0, 0, gx.MaxColorV, gx.MaxColorV},
 	}
@@ -132,6 +132,12 @@ func (p *Player) Update(e *gx.Engine) error {
 		c.R += gx.Pi * p.ScaleSpeed * dt
 	case ebiten.KeyT :
 		c.R -= gx.Pi * p.ScaleSpeed * dt
+	case ebiten.KeyRightBracket :
+		if e.KeyIsPressed(ebiten.KeyShift) {
+			p.R -= gx.Pi * 0.3 * dt
+		} else {
+			p.R += gx.Pi * 0.3 * dt
+		}
 	case ebiten.KeyF :
 		if e.KeyIsPressed(ebiten.KeyShift) {
 			c.S.X -= gx.Pi * p.ScaleSpeed * dt
@@ -150,14 +156,18 @@ func (p *Player) Update(e *gx.Engine) error {
 		} else {
 			c.RA.X += gx.Pi * p.MoveSpeed * dt
 		}
-		log.Println(c.RA.X)
 	case ebiten.KeyX :
 		if e.KeyIsPressed(ebiten.KeyShift) {
 			c.RA.Y -= gx.Pi * p.MoveSpeed * dt
 		} else {
 			c.RA.Y += gx.Pi * p.MoveSpeed * dt
 		}
-		log.Println(c.RA.Y)
+	case ebiten.KeyLeftBracket :
+		if e.KeyIsPressed(ebiten.KeyShift) {
+			rect.R -= gx.Pi * 0.3 * dt
+		} else {
+			rect.R += gx.Pi * 0.3 * dt
+		}
 	case ebiten.Key0 :
 		e.Del(p)
 	}}
@@ -186,7 +196,7 @@ func (d *Debug) Draw(
 func (d *Debug) IsVisible() bool {return true}
 
 func main() {
-	e := gx.New(&gx.WindowConfig{
+	e := gx.NewEngine(&gx.WindowConfig{
 		Title: "Test title",
 		Width: 720,
 		Height: 480,

src/gx/engine.go

@@ -53,7 +53,7 @@ func (e *Engine) Keys() []Key {
 }
 
 // Returns new empty Engine.
-func New(
+func NewEngine(
 	cfg *WindowConfig,
 ) *Engine {
 	w := Float(cfg.Width)
@@ -157,7 +157,8 @@ func (e *engine) Draw(i *ebiten.Image) {
 	eng := (*Engine)(e)
 	for p := range e.layers.Vals() {
 		for pj := range p.V.Range() {
-			if !pj.V.IsVisible() {
+			visibler, ok := pj.V.(Visibler)
+			if ok && !visibler.IsVisible() {
 				continue
 			}
 			pj.V.Draw(eng, i)

src/gx/img.go

@@ -20,6 +20,9 @@ type Color struct {
 // the layers order.
 type Drawer interface {
 	Draw(*Engine, *Image)
+}
+
+type Visibler interface {
 	IsVisible() bool
 }
 

src/gx/sprite.go

@@ -19,9 +19,9 @@ func (s *Sprite) Draw(
 		return
 	}
 	
+	t := s.Rectangle().Transform
 	m := &Matrix{}
-
-	m.Concat(s.Matrix())
+	m.Concat(t.Matrix())
 	if !s.Floating {
 		m.Concat(e.Camera().RealMatrix(
 			e,
@@ -36,8 +36,8 @@ func (s *Sprite) Draw(
 		return
 	}
 	
-	// Drawing with shader.
 	w, h := s.Images[0].Size()
+	// Drawing with shader.
 	opts := &ebiten.DrawRectShaderOptions{
 		Images: s.Images,
 		Uniforms: s.Uniforms,
@@ -46,7 +46,26 @@ func (s *Sprite) Draw(
 	i.DrawRectShader(w, h, s.Shader, opts)
 }
 
+// Check is sprite is visible.
 func (s *Sprite) IsVisible() bool {
 	return s.Visible
 }
 
+// Return the rectangle that contains the sprite.
+func (s *Sprite) Rectangle() Rectangle {
+	if s.Images[0] == nil {
+		panic("trying to get rectangle for nil image pointer")
+	}
+	
+	w, h := s.Images[0].Size()
+	t := s.Transform
+	t.RA.X *= Float(w)
+	t.RA.Y *= Float(h)
+	
+	return Rectangle{t}
+}
+
+func (s *Sprite) Triangles() Triangles {
+	return s.Rectangle().Triangles()
+}
+

src/gx/transform.go

@@ -5,8 +5,17 @@ import (
 	//"math"
 )
 
+// The structure represents basic transformation
+// features: positioning, rotating and scaling.
 type Transform struct {
-	// Position, scale, rotate around(relatively of position, not absolute).
+	// P - absolute phisycal position in engine itself.
+	//
+	// S - scale width and height (X and Y).
+	//
+	// RA - rotate around(relatively of position, not absolute).
+	//
+	// For example RA=Vector{0, 0} will rotate around right up corner
+	// and RA=Vector{.5, .5} will rotate around center.
 	P, S, RA Vector
 	// Rotation angle in radians.
 	R Float
@@ -20,13 +29,27 @@ func T() Transform {
 	return ret
 }
 
+func (t Transform) ScaledToXY(x, y Float) Transform {
+	return t.ScaledToX(x).ScaledToY(y)
+}
+
+func (t Transform) ScaledToX(x Float) Transform {
+	t.S.X = x
+	return t
+}
+
+func (t Transform) ScaledToY(y Float) Transform {
+	t.S.Y = y
+	return t
+}
+
 // Returns the GeoM with corresponding
 // to the transfrom transformation.
 func (t Transform)Matrix() Matrix {
 	g := &Matrix{}
 
 	g.Scale(t.S.X, t.S.Y)
-	g.Translate(-t.RA.X, -t.RA.Y)
+	g.Translate(-t.RA.X * t.S.X, -t.RA.Y * t.S.Y)
 	g.Rotate(t.R)
 	g.Translate(t.P.X, t.P.Y)