mirror of
https://github.com/hajimehoshi/ebiten.git
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274 lines
7.0 KiB
Go
274 lines
7.0 KiB
Go
// Copyright 2016 The Ebiten Authors
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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 jsgo
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package main
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import (
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"bytes"
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"fmt"
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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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"github.com/hajimehoshi/ebiten/examples/resources/images"
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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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maxAngle = 256
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maxLean = 16
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)
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var (
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skyColor = color.RGBA{0x66, 0xcc, 0xff, 0xff}
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thePlayer = &player{
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x16: 16 * 100,
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y16: 16 * 200,
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angle: maxAngle * 3 / 4,
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}
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gophersImage *ebiten.Image
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repeatedGophersImage *ebiten.Image
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groundImage *ebiten.Image
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perspectiveGroundImage *ebiten.Image
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fogImage *ebiten.Image
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)
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func init() {
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// Decode image from a byte slice instead of a file so that
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// this example works in any working directory.
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// If you want to use a file, there are some options:
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// 1) Use os.Open and pass the file to the image decoder.
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// This is a very regular way, but doesn't work on browsers.
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// 2) Use ebitenutil.OpenFile and pass the file to the image decoder.
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// This works even on browsers.
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// 3) Use ebitenutil.NewImageFromFile to create an ebiten.Image directly from a file.
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// This also works on browsers.
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img, _, err := image.Decode(bytes.NewReader(images.Gophers_jpg))
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if err != nil {
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log.Fatal(err)
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}
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gophersImage, _ = ebiten.NewImageFromImage(img, ebiten.FilterDefault)
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groundImage, _ = ebiten.NewImage(screenWidth*2, screenHeight*2/3+50, ebiten.FilterDefault)
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perspectiveGroundImage, _ = ebiten.NewImage(screenWidth*2, screenHeight, ebiten.FilterDefault)
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const repeat = 5
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w, h := gophersImage.Size()
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repeatedGophersImage, _ = ebiten.NewImage(w*repeat, h*repeat, ebiten.FilterDefault)
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for j := 0; j < repeat; j++ {
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for i := 0; i < repeat; i++ {
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op := &ebiten.DrawImageOptions{}
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op.GeoM.Translate(float64(w*i), float64(h*j))
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repeatedGophersImage.DrawImage(gophersImage, op)
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}
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}
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const fogHeight = 8
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w, _ = perspectiveGroundImage.Size()
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fogRGBA := image.NewRGBA(image.Rect(0, 0, w, fogHeight))
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for j := 0; j < fogHeight; j++ {
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a := uint32(float64(fogHeight-1-j) * 0xff / (fogHeight - 1))
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clr := skyColor
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r, g, b, oa := uint32(clr.R), uint32(clr.G), uint32(clr.B), uint32(clr.A)
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clr.R = uint8(r * a / oa)
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clr.G = uint8(g * a / oa)
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clr.B = uint8(b * a / oa)
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clr.A = uint8(a)
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for i := 0; i < w; i++ {
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fogRGBA.SetRGBA(i, j, clr)
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}
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}
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fogImage, _ = ebiten.NewImageFromImage(fogRGBA, ebiten.FilterDefault)
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}
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// player represents the current airship's position.
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type player struct {
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// x16, y16 represents the position in XY plane in fixed float format.
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// The fractional part has 16 bits of precision.
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x16 int
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y16 int
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// angle represents the player's angle in XY plane.
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// angle takes an integer value in [0, maxAngle).
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angle int
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// lean represents the player's leaning.
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// lean takes an integer value in [-maxLean, maxLean].
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lean int
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}
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func round(x float64) float64 {
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return math.Floor(x + 0.5)
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}
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// MoveForward moves the player p forward.
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func (p *player) MoveForward() {
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w, h := gophersImage.Size()
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mx := w * 16
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my := h * 16
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s, c := math.Sincos(float64(p.angle) * 2 * math.Pi / maxAngle)
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p.x16 += int(round(16*c) * 2)
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p.y16 += int(round(16*s) * 2)
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for mx <= p.x16 {
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p.x16 -= mx
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}
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for my <= p.y16 {
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p.y16 -= my
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}
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for p.x16 < 0 {
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p.x16 += mx
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}
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for p.y16 < 0 {
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p.y16 += my
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}
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}
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// RotateRight rotates the player p in the right direction.
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func (p *player) RotateRight() {
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p.angle++
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if maxAngle <= p.angle {
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p.angle -= maxAngle
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}
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p.lean++
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if maxLean < p.lean {
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p.lean = maxLean
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}
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}
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// RotateLeft rotates the player p in the left direction.
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func (p *player) RotateLeft() {
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p.angle--
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if p.angle < 0 {
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p.angle += maxAngle
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}
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p.lean--
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if p.lean < -maxLean {
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p.lean = -maxLean
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}
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}
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// Stabilize tries to move the player in the stable position (lean).
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func (p *player) Stabilize() {
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if 0 < p.lean {
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p.lean--
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}
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if p.lean < 0 {
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p.lean++
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}
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}
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// Position returns the player p's position.
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func (p *player) Position() (int, int) {
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return p.x16, p.y16
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}
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// Angle returns the player p's angle.
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func (p *player) Angle() int {
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return p.angle
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}
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// updateGroundImage updates the ground image according to the current player's position.
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func updateGroundImage(ground *ebiten.Image) {
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ground.Clear()
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x16, y16 := thePlayer.Position()
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a := thePlayer.Angle()
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gw, gh := ground.Size()
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w, h := gophersImage.Size()
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op := &ebiten.DrawImageOptions{}
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op.GeoM.Translate(float64(-x16)/16, float64(-y16)/16)
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op.GeoM.Translate(float64(-w*2), float64(-h*2))
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op.GeoM.Rotate(float64(-a)*2*math.Pi/maxAngle + math.Pi*3.0/2.0)
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op.GeoM.Translate(float64(gw)/2, float64(gh)-32)
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ground.DrawImage(repeatedGophersImage, op)
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}
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// drawGroundImage draws the ground image to the given screen image.
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func drawGroundImage(screen *ebiten.Image, ground *ebiten.Image) {
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perspectiveGroundImage.Clear()
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gw, _ := ground.Size()
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pw, ph := perspectiveGroundImage.Size()
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for j := 0; j < ph; j++ {
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// z is in [2, -1]
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rate := float64(j) / float64(ph)
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z := (1-rate)*2 + rate*-1
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if z <= 0 {
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break
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}
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op := &ebiten.DrawImageOptions{}
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op.GeoM.Translate(-float64(pw)/2, 0)
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op.GeoM.Scale(1/z, 8) // 8 is an arbitrary number not to make empty lines.
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op.GeoM.Translate(float64(pw)/2, float64(j)/z)
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src := image.Rect(0, j, gw, j+1)
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op.SourceRect = &src
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perspectiveGroundImage.DrawImage(ground, op)
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}
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perspectiveGroundImage.DrawImage(fogImage, nil)
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op := &ebiten.DrawImageOptions{}
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op.GeoM.Translate(-float64(pw)/2, 0)
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op.GeoM.Rotate(-1 * float64(thePlayer.lean) / maxLean * math.Pi / 8)
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op.GeoM.Translate(float64(screenWidth)/2, screenHeight/3)
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screen.DrawImage(perspectiveGroundImage, op)
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}
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func update(screen *ebiten.Image) error {
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// Manipulate the player by the input.
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if ebiten.IsKeyPressed(ebiten.KeySpace) {
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thePlayer.MoveForward()
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}
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rotated := false
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if ebiten.IsKeyPressed(ebiten.KeyRight) {
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thePlayer.RotateRight()
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rotated = true
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}
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if ebiten.IsKeyPressed(ebiten.KeyLeft) {
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thePlayer.RotateLeft()
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rotated = true
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}
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if !rotated {
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thePlayer.Stabilize()
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}
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if ebiten.IsRunningSlowly() {
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return nil
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}
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// Draw the ground image.
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screen.Fill(skyColor)
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updateGroundImage(groundImage)
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drawGroundImage(screen, groundImage)
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// Draw the message.
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tutrial := "Space: Move forward\nLeft/Right: Rotate"
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msg := fmt.Sprintf("FPS: %0.2f\n%s", ebiten.CurrentFPS(), tutrial)
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ebitenutil.DebugPrint(screen, msg)
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return nil
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}
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func main() {
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if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Air Ship (Ebiten Demo)"); err != nil {
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log.Fatal(err)
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}
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}
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