mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-12-26 03:38:55 +01:00
144 lines
3.3 KiB
Go
144 lines
3.3 KiB
Go
// Copyright 2016 Hajime Hoshi
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// +build example
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package main
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import (
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"image"
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"image/color"
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_ "image/jpeg"
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"log"
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"math"
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"github.com/hajimehoshi/ebiten"
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"github.com/hajimehoshi/ebiten/ebitenutil"
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)
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const (
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screenWidth = 320
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screenHeight = 240
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)
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var (
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gophersImage *ebiten.Image
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fiveyearsImage *ebiten.Image
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maskImage *ebiten.Image
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spotLightImage *ebiten.Image
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spotLightX = 0
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spotLightY = 0
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spotLightVX = 1
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spotLightVY = 1
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)
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func update(screen *ebiten.Image) error {
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spotLightX += spotLightVX
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spotLightY += spotLightVY
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if spotLightX < 0 {
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spotLightX = -spotLightX
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spotLightVX = -spotLightVX
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}
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if spotLightY < 0 {
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spotLightY = -spotLightY
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spotLightVY = -spotLightVY
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}
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w, h := spotLightImage.Size()
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maxX, maxY := screenWidth-w, screenHeight-h
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if maxX < spotLightX {
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spotLightX = -spotLightX + 2*maxX
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spotLightVX = -spotLightVX
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}
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if maxY < spotLightY {
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spotLightY = -spotLightY + 2*maxY
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spotLightVY = -spotLightVY
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}
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if err := maskImage.Clear(); err != nil {
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return err
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}
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op := &ebiten.DrawImageOptions{}
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op.GeoM.Translate(float64(spotLightX), float64(spotLightY))
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if err := maskImage.DrawImage(spotLightImage, op); err != nil {
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return err
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}
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op = &ebiten.DrawImageOptions{}
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op.CompositeMode = ebiten.CompositeModeSourceOut
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if err := maskImage.DrawImage(fiveyearsImage, op); err != nil {
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return err
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}
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if err := screen.Fill(color.RGBA{0x00, 0x00, 0x80, 0xff}); err != nil {
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return err
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}
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if err := screen.DrawImage(gophersImage, &ebiten.DrawImageOptions{}); err != nil {
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return err
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}
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if err := screen.DrawImage(maskImage, &ebiten.DrawImageOptions{}); err != nil {
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return err
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}
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return nil
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}
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func max(a, b int) int {
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if a < b {
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return b
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}
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return a
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}
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func min(a, b int) int {
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if a < b {
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return a
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}
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return b
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}
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func main() {
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var err error
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gophersImage, _, err = ebitenutil.NewImageFromFile("_resources/images/gophers.jpg", ebiten.FilterNearest)
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if err != nil {
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log.Fatal(err)
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}
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fiveyearsImage, _, err = ebitenutil.NewImageFromFile("_resources/images/fiveyears.jpg", ebiten.FilterNearest)
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if err != nil {
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log.Fatal(err)
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}
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maskImage, err = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
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if err != nil {
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log.Fatal(err)
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}
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as := image.Point{128, 128}
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a := image.NewAlpha(image.Rectangle{image.ZP, as})
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for j := 0; j < as.Y; j++ {
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for i := 0; i < as.X; i++ {
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r := as.X / 2
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d := math.Sqrt(float64((i-r)*(i-r) + (j-r)*(j-r)))
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b := uint8(max(0, min(0xff, 3*0xff-int(d*3*0xff)/r)))
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a.SetAlpha(i, j, color.Alpha{b})
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}
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}
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spotLightImage, err = ebiten.NewImageFromImage(a, ebiten.FilterNearest)
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if err != nil {
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log.Fatal(err)
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}
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if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Masking (Ebiten Demo)"); err != nil {
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log.Fatal(err)
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}
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}
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