mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-11-15 07:27:32 +01:00
103 lines
2.4 KiB
Go
103 lines
2.4 KiB
Go
// Copyright 2017 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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"log"
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"math"
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"github.com/hajimehoshi/ebiten"
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)
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const (
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screenWidth = 640
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screenHeight = 640
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maxIt = 128
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)
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var (
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offscreen *ebiten.Image
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offscreenPix []byte
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palette [maxIt]byte
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)
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func color(it int) (r, g, b byte) {
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if it == maxIt {
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return 0xff, 0xff, 0xff
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}
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c := palette[it]
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return c, c, c
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}
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func updateOffscreen(centerX, centerY, size float64) {
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for j := 0; j < screenHeight; j++ {
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for i := 0; i < screenHeight; i++ {
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x := float64(i)*size/screenWidth - size/2 + centerX
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y := (screenHeight-float64(j))*size/screenHeight - size/2 + centerY
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c := complex(x, y)
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z := complex(0, 0)
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it := 0
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for ; it < maxIt; it++ {
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z = z*z + c
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if real(z)*real(z)+imag(z)*imag(z) > 4 {
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break
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}
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}
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r, g, b := color(it)
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p := 4 * (i + j*screenWidth)
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offscreenPix[p] = r
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offscreenPix[p+1] = g
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offscreenPix[p+2] = b
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offscreenPix[p+3] = 0xff
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}
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}
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offscreen.ReplacePixels(offscreenPix)
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}
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func init() {
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offscreen, _ = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterDefault)
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offscreenPix = make([]byte, screenWidth*screenHeight*4)
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for i := range palette {
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palette[i] = byte(math.Sqrt(float64(i)/float64(len(palette))) * 0x80)
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}
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// Now it is not feasible to call updateOffscreen every frame due to performance.
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updateOffscreen(-0.75, 0.25, 2)
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}
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type Game struct {
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}
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func (g *Game) Update(screen *ebiten.Image) error {
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return nil
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}
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func (g *Game) Draw(screen *ebiten.Image) {
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screen.DrawImage(offscreen, nil)
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}
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func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
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return screenWidth, screenHeight
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}
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func main() {
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ebiten.SetWindowSize(screenWidth, screenHeight)
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ebiten.SetWindowTitle("Mandelbrot (Ebiten Demo)")
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if err := ebiten.RunGame(&Game{}); err != nil {
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log.Fatal(err)
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}
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}
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