forked from hajimehoshi/ebiten
/
scenemanager.go
98 lines (84 loc) · 2.2 KB
/
scenemanager.go
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// Copyright 2014 Hajime Hoshi
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package blocks
import (
"github.com/hajimehoshi/ebiten"
)
var (
transitionFrom *ebiten.Image
transitionTo *ebiten.Image
)
func init() {
var err error
transitionFrom, err = ebiten.NewImage(ScreenWidth, ScreenHeight, ebiten.FilterNearest)
if err != nil {
panic(err)
}
transitionTo, err = ebiten.NewImage(ScreenWidth, ScreenHeight, ebiten.FilterNearest)
if err != nil {
panic(err)
}
}
type Scene interface {
Update(state *GameState) error
Draw(screen *ebiten.Image) error
}
const transitionMaxCount = 20
type SceneManager struct {
current Scene
next Scene
transitionCount int
}
func NewSceneManager(initScene Scene) *SceneManager {
return &SceneManager{
current: initScene,
transitionCount: -1,
}
}
func (s *SceneManager) Update(state *GameState) error {
if s.transitionCount == -1 {
return s.current.Update(state)
}
s.transitionCount++
if transitionMaxCount <= s.transitionCount {
s.current = s.next
s.next = nil
s.transitionCount = -1
}
return nil
}
func (s *SceneManager) Draw(r *ebiten.Image) error {
if s.transitionCount == -1 {
return s.current.Draw(r)
}
transitionFrom.Clear()
if err := s.current.Draw(transitionFrom); err != nil {
return err
}
transitionTo.Clear()
if err := s.next.Draw(transitionTo); err != nil {
return err
}
if err := r.DrawImage(transitionFrom, nil); err != nil {
return err
}
alpha := float64(s.transitionCount) / float64(transitionMaxCount)
op := &ebiten.DrawImageOptions{}
op.ColorM.Scale(1, 1, 1, alpha)
return r.DrawImage(transitionTo, op)
}
func (s *SceneManager) GoTo(scene Scene) {
s.next = scene
s.transitionCount = 0
}