ebiten/examples/hsv/main.go

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// Copyright 2016 Hajime Hoshi
//
// 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 (
"bytes"
"fmt"
"image"
_ "image/jpeg"
"log"
"math"
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"github.com/hajimehoshi/ebiten/v2"
"github.com/hajimehoshi/ebiten/v2/ebitenutil"
"github.com/hajimehoshi/ebiten/v2/examples/resources/images"
"github.com/hajimehoshi/ebiten/v2/inpututil"
)
const (
screenWidth = 640
screenHeight = 480
)
var (
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gophersImage *ebiten.Image
)
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// clamp clamps v to the range [min, max].
func clamp(v, min, max int) int {
if min > max {
panic("min must <= max")
}
if v < min {
return min
}
if max < v {
return max
}
return v
}
type Game struct {
hue128 int
saturation128 int
value128 int
inverted bool
}
func NewGame() *Game {
return &Game{
saturation128: 128,
value128: 128,
}
}
func (g *Game) Update() error {
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// Adjust HSV values along with the user's input.
if ebiten.IsKeyPressed(ebiten.KeyQ) {
g.hue128--
}
if ebiten.IsKeyPressed(ebiten.KeyW) {
g.hue128++
}
if ebiten.IsKeyPressed(ebiten.KeyA) {
g.saturation128--
}
if ebiten.IsKeyPressed(ebiten.KeyS) {
g.saturation128++
}
if ebiten.IsKeyPressed(ebiten.KeyZ) {
g.value128--
}
if ebiten.IsKeyPressed(ebiten.KeyX) {
g.value128++
}
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g.hue128 = clamp(g.hue128, -256, 256)
g.saturation128 = clamp(g.saturation128, 0, 256)
g.value128 = clamp(g.value128, 0, 256)
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if inpututil.IsKeyJustPressed(ebiten.KeyI) {
g.inverted = !g.inverted
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}
return nil
}
func (g *Game) Draw(screen *ebiten.Image) {
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// Center the image on the screen.
w, h := gophersImage.Size()
op := &ebiten.DrawImageOptions{}
op.GeoM.Translate(-float64(w)/2, -float64(h)/2)
op.GeoM.Scale(2, 2)
op.GeoM.Translate(float64(screenWidth)/2, float64(screenHeight)/2)
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// Change HSV.
hue := float64(g.hue128) * 2 * math.Pi / 128
saturation := float64(g.saturation128) / 128
value := float64(g.value128) / 128
op.ColorM.ChangeHSV(hue, saturation, value)
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// Invert the color.
if g.inverted {
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op.ColorM.Scale(-1, -1, -1, 1)
op.ColorM.Translate(1, 1, 1, 0)
}
screen.DrawImage(gophersImage, op)
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// Draw the text of the current status.
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msgInverted := "false"
if g.inverted {
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msgInverted = "true"
}
msg := fmt.Sprintf(`Hue: %0.2f [Q][W]
Saturation: %0.2f [A][S]
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Value: %0.2f [Z][X]
Inverted: %s [I]`, hue, saturation, value, msgInverted)
ebitenutil.DebugPrint(screen, msg)
}
func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
return screenWidth, screenHeight
}
func main() {
// Decode image from a byte slice instead of a file so that
// this example works in any working directory.
// If you want to use a file, there are some options:
// 1) Use os.Open and pass the file to the image decoder.
// This is a very regular way, but doesn't work on browsers.
// 2) Use ebitenutil.OpenFile and pass the file to the image decoder.
// This works even on browsers.
// 3) Use ebitenutil.NewImageFromFile to create an ebiten.Image directly from a file.
// This also works on browsers.
img, _, err := image.Decode(bytes.NewReader(images.Gophers_jpg))
if err != nil {
log.Fatal(err)
}
gophersImage = ebiten.NewImageFromImage(img)
ebiten.SetWindowSize(screenWidth, screenHeight)
ebiten.SetWindowTitle("HSV (Ebiten Demo)")
if err := ebiten.RunGame(NewGame()); err != nil {
log.Fatal(err)
}
}