2018-03-11 17:33:52 +01:00
<!DOCTYPE html>
< meta charset = "utf-8" >
< meta property = "og:image" itemprop = "image primaryImageOfPage" content = "https://hajimehoshi.github.io/ebiten/images/examples/airship.png" >
< meta name = "description" content = "Ebiten example - airship" >
< link rel = "shortcut icon" href = "../favicon.png" type = "image/png" >
< link rel = "icon" href = "../favicon.png" type = "image/png" >
< title > Ebiten example - airship< / title >
< link rel = "stylesheet" href = "../stylesheets/bootstrap.min.css" >
< link rel = "stylesheet" href = "../stylesheets/highlight-github.css" >
< link rel = "stylesheet" href = "../stylesheets/ebiten.css" >
< script src = "../scripts/googleanalytics.js" > < / script >
< nav class = "navbar" > < div class = "container" >
< nav class = "d-flex flex-row" style = "width: 100%;" >
< div class = "nav mr-auto" > < a class = "navbar-brand" href = "../" > < img src = "../images/logo_white.svg" alt = "EBITEN" > < / a > < / div >
< ul class = "nav" >
< li class = "nav-item" > < a class = "nav-link" href = "https://github.com/hajimehoshi/ebiten" > GitHub< / a > < / li >
< li class = "nav-item" > < a class = "nav-link" href = "https://godoc.org/github.com/hajimehoshi/ebiten" > GoDoc< / a > < / li >
< li class = "nav-item" > < a class = "nav-link" href = "https://github.com/hajimehoshi/ebiten/wiki" > Wiki< / a >
< li class = "nav-item" > < a class = "nav-link" href = "https://ebiten-playground.github.io/" > Playground< / a >
< / ul >
< / nav >
< / div > < / nav >
< main > < div class = "container" >
< h2 > Ebiten example - airship< / h2 >
< iframe src = "airship.content.html" width = "640" height = "480" > < / iframe >
2018-03-21 06:34:48 +01:00
< div class = "card" > < pre class = "card-body" > < code class = "language-go" > // + build example jsgo
2018-03-11 17:33:52 +01:00
package main
import (
2018-03-21 06:34:48 +01:00
" bytes"
2018-03-11 17:33:52 +01:00
" fmt"
" image"
" image/color"
_ " image/jpeg"
" log"
" math"
" github.com/hajimehoshi/ebiten"
" github.com/hajimehoshi/ebiten/ebitenutil"
2018-03-21 06:34:48 +01:00
" github.com/hajimehoshi/ebiten/examples/resources/images"
2018-03-11 17:33:52 +01:00
)
const (
screenWidth = 320
screenHeight = 240
maxAngle = 256
maxLean = 16
)
var (
skyColor = color.RGBA{0x66, 0xcc, 0xff, 0xff}
thePlayer = & player{
x16: 16 * 100,
y16: 16 * 200,
angle: maxAngle * 3 / 4,
}
gophersImage *ebiten.Image
repeatedGophersImage *ebiten.Image
groundImage *ebiten.Image
perspectiveGroundImage *ebiten.Image
fogImage *ebiten.Image
)
func init() {
2018-03-21 06:34:48 +01:00
// Decode image from a byte slice instead of a file so that
// this example works in any working directory.
// If you want to use a file, there are some options:
// 1) Use os.Open and pass the file to the image decoder.
// This is a very regular way, but doesn' t work on browsers.
// 2) Use ebitenutil.OpenFile and pass the file to the image decoder.
// This works even on browsers.
// 3) Use ebitenutil.NewImageFromFile to create an ebiten.Image directly from a file.
// This also works on browsers.
img, _, err := image.Decode(bytes.NewReader(images.Gophers_jpg))
2018-03-11 17:33:52 +01:00
if err != nil {
2018-03-21 06:34:48 +01:00
log.Fatal(err)
2018-03-11 17:33:52 +01:00
}
2018-03-21 06:34:48 +01:00
gophersImage, _ = ebiten.NewImageFromImage(img, ebiten.FilterDefault)
2018-03-11 17:33:52 +01:00
groundImage, _ = ebiten.NewImage(screenWidth*2, screenHeight*2/3+ 50, ebiten.FilterDefault)
perspectiveGroundImage, _ = ebiten.NewImage(screenWidth*2, screenHeight, ebiten.FilterDefault)
const repeat = 5
w, h := gophersImage.Size()
repeatedGophersImage, _ = ebiten.NewImage(w*repeat, h*repeat, ebiten.FilterDefault)
for j := 0; j < repeat; j+ + {
for i := 0; i < repeat; i+ + {
op := & ebiten.DrawImageOptions{}
op.GeoM.Translate(float64(w*i), float64(h*j))
repeatedGophersImage.DrawImage(gophersImage, op)
}
}
const fogHeight = 8
w, _ = perspectiveGroundImage.Size()
fogRGBA := image.NewRGBA(image.Rect(0, 0, w, fogHeight))
for j := 0; j < fogHeight; j+ + {
a := uint32(float64(fogHeight-1-j) * 0xff / (fogHeight - 1))
clr := skyColor
r, g, b, oa := uint32(clr.R), uint32(clr.G), uint32(clr.B), uint32(clr.A)
clr.R = uint8(r * a / oa)
clr.G = uint8(g * a / oa)
clr.B = uint8(b * a / oa)
clr.A = uint8(a)
for i := 0; i < w; i+ + {
fogRGBA.SetRGBA(i, j, clr)
}
}
fogImage, _ = ebiten.NewImageFromImage(fogRGBA, ebiten.FilterDefault)
}
// player represents the current airship' s position.
type player struct {
// x16, y16 represents the position in XY plane in fixed float format.
// The fractional part has 16 bits of precision.
x16 int
y16 int
// angle represents the player' s angle in XY plane.
// angle takes an integer value in [0, maxAngle).
angle int
// lean represents the player' s leaning.
// lean takes an integer value in [-maxLean, maxLean].
lean int
}
func round(x float64) float64 {
return math.Floor(x + 0.5)
}
// MoveForward moves the player p forward.
func (p *player) MoveForward() {
w, h := gophersImage.Size()
mx := w * 16
my := h * 16
s, c := math.Sincos(float64(p.angle) * 2 * math.Pi / maxAngle)
p.x16 + = int(round(16*c) * 2)
p.y16 + = int(round(16*s) * 2)
for mx < = p.x16 {
p.x16 -= mx
}
for my < = p.y16 {
p.y16 -= my
}
for p.x16 < 0 {
p.x16 + = mx
}
for p.y16 < 0 {
p.y16 + = my
}
}
// RotateRight rotates the player p in the right direction.
func (p *player) RotateRight() {
p.angle+ +
if maxAngle < = p.angle {
p.angle -= maxAngle
}
p.lean+ +
if maxLean < p.lean {
p.lean = maxLean
}
}
// RotateLeft rotates the player p in the left direction.
func (p *player) RotateLeft() {
p.angle--
if p.angle < 0 {
p.angle + = maxAngle
}
p.lean--
if p.lean < -maxLean {
p.lean = -maxLean
}
}
// Stabilize tries to move the player in the stable position (lean).
func (p *player) Stabilize() {
if 0 < p.lean {
p.lean--
}
if p.lean < 0 {
p.lean+ +
}
}
// Position returns the player p' s position.
func (p *player) Position() (int, int) {
return p.x16, p.y16
}
// Angle returns the player p' s angle.
func (p *player) Angle() int {
return p.angle
}
// updateGroundImage updates the ground image according to the current player' s position.
func updateGroundImage(ground *ebiten.Image) {
ground.Clear()
x16, y16 := thePlayer.Position()
a := thePlayer.Angle()
gw, gh := ground.Size()
w, h := gophersImage.Size()
op := & ebiten.DrawImageOptions{}
op.GeoM.Translate(float64(-x16)/16, float64(-y16)/16)
op.GeoM.Translate(float64(-w*2), float64(-h*2))
op.GeoM.Rotate(float64(-a)*2*math.Pi/maxAngle + math.Pi*3.0/2.0)
op.GeoM.Translate(float64(gw)/2, float64(gh)-32)
ground.DrawImage(repeatedGophersImage, op)
}
// drawGroundImage draws the ground image to the given screen image.
func drawGroundImage(screen *ebiten.Image, ground *ebiten.Image) {
perspectiveGroundImage.Clear()
gw, _ := ground.Size()
pw, ph := perspectiveGroundImage.Size()
for j := 0; j < ph; j+ + {
2018-03-21 06:34:48 +01:00
// z is in [2, -1]
2018-03-11 17:33:52 +01:00
rate := float64(j) / float64(ph)
2018-03-21 06:34:48 +01:00
z := (1-rate)*2 + rate*-1
2018-03-11 19:23:29 +01:00
if z < = 0 {
break
}
2018-03-11 17:33:52 +01:00
op := & ebiten.DrawImageOptions{}
op.GeoM.Translate(-float64(pw)/2, 0)
2018-03-11 19:20:58 +01:00
op.GeoM.Scale(1/z, 8) // 8 is an arbitrary number not to make empty lines.
2018-03-11 17:33:52 +01:00
op.GeoM.Translate(float64(pw)/2, float64(j)/z)
src := image.Rect(0, j, gw, j+ 1)
op.SourceRect = & src
perspectiveGroundImage.DrawImage(ground, op)
}
perspectiveGroundImage.DrawImage(fogImage, nil)
op := & ebiten.DrawImageOptions{}
op.GeoM.Translate(-float64(pw)/2, 0)
op.GeoM.Rotate(-1 * float64(thePlayer.lean) / maxLean * math.Pi / 8)
op.GeoM.Translate(float64(screenWidth)/2, screenHeight/3)
screen.DrawImage(perspectiveGroundImage, op)
}
func update(screen *ebiten.Image) error {
// Manipulate the player by the input.
if ebiten.IsKeyPressed(ebiten.KeySpace) {
thePlayer.MoveForward()
}
rotated := false
if ebiten.IsKeyPressed(ebiten.KeyRight) {
thePlayer.RotateRight()
rotated = true
}
if ebiten.IsKeyPressed(ebiten.KeyLeft) {
thePlayer.RotateLeft()
rotated = true
}
if !rotated {
thePlayer.Stabilize()
}
if ebiten.IsRunningSlowly() {
return nil
}
// Draw the ground image.
screen.Fill(skyColor)
updateGroundImage(groundImage)
drawGroundImage(screen, groundImage)
// Draw the message.
tutrial := " Space: Move forward\nLeft/Right: Rotate"
msg := fmt.Sprintf(" FPS: %0.2f\n%s" , ebiten.CurrentFPS(), tutrial)
ebitenutil.DebugPrint(screen, msg)
return nil
}
func main() {
if err := ebiten.Run(update, screenWidth, screenHeight, 2, " Air Ship (Ebiten Demo)" ); err != nil {
log.Fatal(err)
}
}
< / code > < / pre > < / div >
< / div > < / main >
< footer > < div class = "container" >
< p > © 2013 Hajime Hoshi< / p >
< p > Code is licensed under < a href = "https://github.com/hajimehoshi/ebiten/blob/master/LICENSE" > the Apache License 2.0< / a > .< / p >
< p > The content of this page is licensed under < a href = "https://creativecommons.org/licenses/by/4.0/" > the Creative Commons Attribution 4.0 License< / a > .< / p >
< / div > < / footer >
< script src = "../scripts/highlight.pack.js" > < / script >
< script > hljs . initHighlightingOnLoad ( ) ; < / script >
