mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-12-25 03:08:54 +01:00
74 lines
1.8 KiB
Go
74 lines
1.8 KiB
Go
// Copyright 2015 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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package main
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import (
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"fmt"
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"image"
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"log"
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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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noiseImage *image.RGBA
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)
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type rand struct {
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x, y, z, w uint32
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}
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func (r *rand) next() uint32 {
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// math/rand is too slow to keep 60 FPS on web browsers.
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// Use Xorshift instead: http://en.wikipedia.org/wiki/Xorshift
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t := r.x ^ (r.x << 11)
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r.x, r.y, r.z = r.y, r.z, r.w
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r.w = (r.w ^ (r.w >> 19)) ^ (t ^ (t >> 8))
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return r.w
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}
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var randInstance = &rand{12345678, 4185243, 776511, 45411}
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func update(screen *ebiten.Image) error {
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const l = screenWidth * screenHeight
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for i := 0; i < l; i++ {
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x := randInstance.next()
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noiseImage.Pix[4*i] = uint8(x >> 24)
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noiseImage.Pix[4*i+1] = uint8(x >> 16)
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noiseImage.Pix[4*i+2] = uint8(x >> 8)
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noiseImage.Pix[4*i+3] = 0xff
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}
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if err := screen.ReplacePixels(noiseImage.Pix); err != nil {
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return err
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}
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if err := ebitenutil.DebugPrint(screen, fmt.Sprintf("FPS: %f", ebiten.CurrentFPS())); 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 main() {
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noiseImage = image.NewRGBA(image.Rect(0, 0, screenWidth, screenHeight))
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if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Noise (Ebiten Demo)"); err != nil {
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log.Fatal(err)
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}
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}
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