ebiten/examples/doomfire/main.go

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// Copyright 2019 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
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//go:build example
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// +build example
package main
import (
"image/color"
"log"
"math/rand"
"time"
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"github.com/hajimehoshi/ebiten/v2"
)
const (
screenWidth = 100
screenHeight = 50
screenSize = screenWidth * screenHeight
)
var (
pixels = make([]byte, screenSize*4)
firePalette = []color.RGBA{
{R: 7, G: 7, B: 7, A: 255}, // 0
{R: 31, G: 7, B: 7, A: 255}, // 1
{R: 47, G: 15, B: 7, A: 255}, // 2
{R: 71, G: 15, B: 7, A: 255}, // 3
{R: 87, G: 23, B: 7, A: 255}, // 4
{R: 103, G: 31, B: 7, A: 255}, // 5
{R: 119, G: 31, B: 7, A: 255}, // 6
{R: 143, G: 39, B: 7, A: 255}, // 7
{R: 159, G: 47, B: 7, A: 255}, // 8
{R: 175, G: 63, B: 7, A: 255}, // 9
{R: 191, G: 71, B: 7, A: 255}, // 10
{R: 199, G: 71, B: 7, A: 255}, // 11
{R: 223, G: 79, B: 7, A: 255}, // 12
{R: 223, G: 87, B: 7, A: 255}, // 13
{R: 223, G: 87, B: 7, A: 255}, // 14
{R: 215, G: 95, B: 7, A: 255}, // 15
{R: 215, G: 95, B: 7, A: 255}, // 16
{R: 215, G: 103, B: 15, A: 255}, // 17
{R: 207, G: 111, B: 15, A: 255}, // 18
{R: 207, G: 119, B: 15, A: 255}, // 19
{R: 207, G: 127, B: 15, A: 255}, // 20
{R: 207, G: 135, B: 23, A: 255}, // 21
{R: 199, G: 135, B: 23, A: 255}, // 22
{R: 199, G: 143, B: 23, A: 255}, // 23
{R: 199, G: 151, B: 31, A: 255}, // 24
{R: 191, G: 159, B: 31, A: 255}, // 25
{R: 191, G: 159, B: 31, A: 255}, // 26
{R: 191, G: 167, B: 39, A: 255}, // 27
{R: 191, G: 167, B: 39, A: 255}, // 28
{R: 191, G: 175, B: 47, A: 255}, // 29
{R: 183, G: 175, B: 47, A: 255}, // 30
{R: 183, G: 183, B: 47, A: 255}, // 31
{R: 183, G: 183, B: 55, A: 255}, // 32
{R: 207, G: 207, B: 111, A: 255}, // 33
{R: 223, G: 223, B: 159, A: 255}, // 34
{R: 239, G: 239, B: 199, A: 255}, // 35
{R: 255, G: 255, B: 255, A: 255}, // 36
}
)
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type Game struct {
firePixels []byte
}
func NewGame() *Game {
firePixels := make([]byte, screenSize)
for i := screenSize - screenWidth; i < screenSize; i++ {
firePixels[i] = 36
}
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return &Game{
firePixels: firePixels,
}
}
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func (g *Game) updateFirePixels() {
for i := 0; i < screenWidth; i++ {
for j := 0; j < screenHeight; j++ {
idx := i + (screenWidth * j)
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g.updateFireIntensityPerPixel(idx)
}
}
}
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func (g *Game) updateFireIntensityPerPixel(currentPixelIndex int) {
below := currentPixelIndex + screenWidth
if below >= screenSize {
return
}
d := rand.Intn(3)
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newI := int(g.firePixels[below]) - d
if newI < 0 {
newI = 0
}
if currentPixelIndex-d < 0 {
return
}
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g.firePixels[currentPixelIndex-d] = byte(newI)
}
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func (g *Game) renderFire() {
for i, v := range g.firePixels {
p := firePalette[v]
pixels[i*4] = p.R
pixels[i*4+1] = p.G
pixels[i*4+2] = p.B
pixels[i*4+3] = p.A
}
}
func (g *Game) Update() error {
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g.updateFirePixels()
return nil
}
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func (g *Game) Draw(screen *ebiten.Image) {
g.renderFire()
screen.ReplacePixels(pixels)
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}
func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
return screenWidth, screenHeight
}
func main() {
rand.Seed(time.Now().UnixNano())
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ebiten.SetWindowSize(screenWidth*6, screenHeight*6)
ebiten.SetWindowTitle("Doom Fire (Ebiten Demo)")
if err := ebiten.RunGame(NewGame()); err != nil {
log.Fatal(err)
}
}