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.
// +build example
package main
import (
"fmt"
_ "image/jpeg"
"log"
"math"
"github.com/hajimehoshi/ebiten"
"github.com/hajimehoshi/ebiten/ebitenutil"
)
const (
screenWidth = 320
screenHeight = 240
)
var (
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hue128 = 0
saturation128 = 128
value128 = 128
inverted = false
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prevPressedI = false
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
}
func update(screen *ebiten.Image) error {
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// Adjust HSV values along with the user's input.
if ebiten.IsKeyPressed(ebiten.KeyQ) {
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hue128--
}
if ebiten.IsKeyPressed(ebiten.KeyW) {
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hue128++
}
if ebiten.IsKeyPressed(ebiten.KeyA) {
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saturation128--
}
if ebiten.IsKeyPressed(ebiten.KeyS) {
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saturation128++
}
if ebiten.IsKeyPressed(ebiten.KeyZ) {
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value128--
}
if ebiten.IsKeyPressed(ebiten.KeyX) {
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value128++
}
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hue128 = clamp(hue128, -256, 256)
saturation128 = clamp(saturation128, 0, 256)
value128 = clamp(value128, 0, 256)
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pressedI := ebiten.IsKeyPressed(ebiten.KeyI)
if pressedI && !prevPressedI {
inverted = !inverted
}
prevPressedI = pressedI
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if ebiten.IsRunningSlowly() {
return nil
}
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// Center the image on the screen.
w, h := gophersImage.Size()
op := &ebiten.DrawImageOptions{}
op.GeoM.Translate(float64(screenWidth-w)/2, float64(screenHeight-h)/2)
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// Change HSV.
hue := float64(hue128) * 2 * math.Pi / 128
saturation := float64(saturation128) / 128
value := float64(value128) / 128
op.ColorM.ChangeHSV(hue, saturation, value)
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// Invert the color.
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if inverted {
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 inverted {
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)
return nil
}
func main() {
var err error
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gophersImage, _, err = ebitenutil.NewImageFromFile("_resources/images/gophers.jpg", ebiten.FilterDefault)
if err != nil {
log.Fatal(err)
}
if err := ebiten.Run(update, screenWidth, screenHeight, 2, "HSV (Ebiten Demo)"); err != nil {
log.Fatal(err)
}
}