mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-12-25 03:08:54 +01:00
98 lines
2.2 KiB
Go
98 lines
2.2 KiB
Go
// Copyright 2017 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.
|
|
|
|
// +build example jsgo
|
|
|
|
package main
|
|
|
|
import (
|
|
"log"
|
|
"math"
|
|
|
|
"github.com/hajimehoshi/ebiten"
|
|
)
|
|
|
|
const (
|
|
screenWidth = 640
|
|
screenHeight = 640
|
|
maxIt = 128
|
|
)
|
|
|
|
var (
|
|
offscreen *ebiten.Image
|
|
offscreenPix []byte
|
|
palette [maxIt]byte
|
|
)
|
|
|
|
func init() {
|
|
offscreen, _ = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterDefault)
|
|
offscreenPix = make([]byte, screenWidth*screenHeight*4)
|
|
for i := range palette {
|
|
palette[i] = byte(math.Sqrt(float64(i)/float64(len(palette))) * 0x80)
|
|
}
|
|
}
|
|
|
|
func color(it int) (r, g, b byte) {
|
|
if it == maxIt {
|
|
return 0xff, 0xff, 0xff
|
|
}
|
|
c := palette[it]
|
|
return c, c, c
|
|
}
|
|
|
|
func updateOffscreen(centerX, centerY, size float64) {
|
|
for j := 0; j < screenHeight; j++ {
|
|
for i := 0; i < screenHeight; i++ {
|
|
x := float64(i)*size/screenWidth - size/2 + centerX
|
|
y := (screenHeight-float64(j))*size/screenHeight - size/2 + centerY
|
|
c := complex(x, y)
|
|
z := complex(0, 0)
|
|
it := 0
|
|
for ; it < maxIt; it++ {
|
|
z = z*z + c
|
|
if real(z)*real(z)+imag(z)*imag(z) > 4 {
|
|
break
|
|
}
|
|
}
|
|
r, g, b := color(it)
|
|
p := 4 * (i + j*screenWidth)
|
|
offscreenPix[p] = r
|
|
offscreenPix[p+1] = g
|
|
offscreenPix[p+2] = b
|
|
offscreenPix[p+3] = 0xff
|
|
}
|
|
}
|
|
offscreen.ReplacePixels(offscreenPix)
|
|
}
|
|
|
|
func init() {
|
|
// Now it is not feasible to call updateOffscreen every frame due to performance.
|
|
updateOffscreen(-0.75, 0.25, 2)
|
|
}
|
|
|
|
func update(screen *ebiten.Image) error {
|
|
if ebiten.IsRunningSlowly() {
|
|
return nil
|
|
}
|
|
|
|
screen.DrawImage(offscreen, nil)
|
|
return nil
|
|
}
|
|
|
|
func main() {
|
|
if err := ebiten.Run(update, screenWidth, screenHeight, 1, "Mandelbrot (Ebiten Demo)"); err != nil {
|
|
log.Fatal(err)
|
|
}
|
|
}
|