ebiten/gameforui.go

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// Copyright 2014 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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package ebiten
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import (
"fmt"
"image"
"math"
"sync/atomic"
"github.com/hajimehoshi/ebiten/v2/internal/atlas"
"github.com/hajimehoshi/ebiten/v2/internal/ui"
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)
const screenShaderSrc = `package main
func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
// TODO: Calculate the scale in the shader after pixels become the main unit in shaders (#1431)
_, dr := imageDstRegionOnTexture()
_, sr := imageSrcRegionOnTexture()
scale := (imageDstTextureSize() * dr) / (imageSrcTextureSize() * sr)
sourceSize := imageSrcTextureSize()
// texelSize is one pixel size in texel sizes.
texelSize := 1 / sourceSize
halfScaledTexelSize := texelSize / 2 / scale
// Shift 1/512 [texel] to avoid the tie-breaking issue.
pos := texCoord
p0 := pos - halfScaledTexelSize + (texelSize / 512)
p1 := pos + halfScaledTexelSize + (texelSize / 512)
// Texels must be in the source rect, so it is not necessary to check.
c0 := imageSrc0UnsafeAt(p0)
c1 := imageSrc0UnsafeAt(vec2(p1.x, p0.y))
c2 := imageSrc0UnsafeAt(vec2(p0.x, p1.y))
c3 := imageSrc0UnsafeAt(p1)
// p is the p1 value in one pixel assuming that the pixel's upper-left is (0, 0) and the lower-right is (1, 1).
p := fract(p1 * sourceSize)
// rate indicates how much the 4 colors are mixed. rate is in between [0, 1].
//
// 0 <= p <= 1/Scale: The rate is in between [0, 1]
// 1/Scale < p: Don't care. Adjacent colors (e.g. c0 vs c1 in an X direction) should be the same.
rate := clamp(p*scale, 0, 1)
return mix(mix(c0, c1, rate.x), mix(c2, c3, rate.x), rate.y)
}
`
var screenFilterEnabled = int32(1)
func isScreenFilterEnabled() bool {
return atomic.LoadInt32(&screenFilterEnabled) != 0
}
func setScreenFilterEnabled(enabled bool) {
v := int32(0)
if enabled {
v = 1
}
atomic.StoreInt32(&screenFilterEnabled, v)
}
type gameForUI struct {
game Game
offscreen *Image
screen *Image
screenShader *Shader
imageDumper imageDumper
}
func newGameForUI(game Game) *gameForUI {
g := &gameForUI{
game: game,
}
s, err := NewShader([]byte(screenShaderSrc))
if err != nil {
panic(fmt.Sprintf("ebiten: compiling the screen shader failed: %v", err))
}
g.screenShader = s
return g
}
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func (g *gameForUI) NewOffscreenImage(width, height int) *ui.Image {
if g.offscreen != nil {
g.offscreen.Dispose()
g.offscreen = nil
}
// Keep the offscreen an unmanaged image that is always isolated from an atlas (#1938).
// The shader program for the screen is special and doesn't work well with an image on an atlas.
// An image on an atlas is surrounded by a transparent edge,
// and the shader program unexpectedly picks the pixel on the edges.
imageType := atlas.ImageTypeUnmanaged
if ui.IsScreenClearedEveryFrame() {
// A violatile image is also always isolated.
imageType = atlas.ImageTypeVolatile
}
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g.offscreen = newImage(image.Rect(0, 0, width, height), imageType)
return g.offscreen.image
}
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func (g *gameForUI) NewScreenImage(width, height int) *ui.Image {
if g.screen != nil {
g.screen.Dispose()
g.screen = nil
}
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g.screen = newImage(image.Rect(0, 0, width, height), atlas.ImageTypeScreen)
return g.screen.image
}
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func (g *gameForUI) Layout(outsideWidth, outsideHeight int) (int, int) {
return g.game.Layout(outsideWidth, outsideHeight)
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}
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func (g *gameForUI) Update() error {
if err := g.game.Update(); err != nil {
return err
}
if err := g.imageDumper.update(); err != nil {
return err
}
return nil
}
func (g *gameForUI) DrawOffscreen() error {
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g.game.Draw(g.offscreen)
if err := g.imageDumper.dump(g.offscreen); err != nil {
return err
}
return nil
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}
func (g *gameForUI) DrawFinalScreen() {
scale, offsetX, offsetY := g.ScreenScaleAndOffsets()
var geoM GeoM
geoM.Scale(scale, scale)
geoM.Translate(offsetX, offsetY)
if d, ok := g.game.(FinalScreenDrawer); ok {
d.DrawFinalScreen(g.screen, g.offscreen, geoM)
return
}
switch {
case !isScreenFilterEnabled(), math.Floor(scale) == scale:
op := &DrawImageOptions{}
op.GeoM = geoM
g.screen.DrawImage(g.offscreen, op)
case scale < 1:
op := &DrawImageOptions{}
op.GeoM = geoM
op.Filter = FilterLinear
g.screen.DrawImage(g.offscreen, op)
default:
op := &DrawRectShaderOptions{}
op.Images[0] = g.offscreen
op.GeoM = geoM
w, h := g.offscreen.Size()
g.screen.DrawRectShader(w, h, g.screenShader, op)
}
}
func (g *gameForUI) ScreenScaleAndOffsets() (scale, offsetX, offsetY float64) {
if g.screen == nil {
return
}
sw, sh := g.screen.Size()
ow, oh := g.offscreen.Size()
scaleX := float64(sw) / float64(ow)
scaleY := float64(sh) / float64(oh)
scale = math.Min(scaleX, scaleY)
width := float64(ow) * scale
height := float64(oh) * scale
offsetX = (float64(sw) - width) / 2
offsetY = (float64(sh) - height) / 2
return
}