ebiten/internal/ui/context.go

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// Copyright 2022 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.
package ui
import (
"fmt"
"math"
"sync"
"sync/atomic"
"github.com/hajimehoshi/ebiten/v2/internal/affine"
"github.com/hajimehoshi/ebiten/v2/internal/atlas"
"github.com/hajimehoshi/ebiten/v2/internal/buffered"
"github.com/hajimehoshi/ebiten/v2/internal/clock"
"github.com/hajimehoshi/ebiten/v2/internal/debug"
"github.com/hajimehoshi/ebiten/v2/internal/graphics"
"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver"
"github.com/hajimehoshi/ebiten/v2/internal/hooks"
)
const screenShader = `package main
var Scale float
func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
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.
// As all the vertex positions are aligned to 1/16 [pixel], this shiting should work in most cases.
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].
//
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// 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)
}
`
type Game interface {
NewOffscreenImage(width, height int) *Image
Layout(outsideWidth, outsideHeight int) (int, int)
Update() error
Draw()
}
type context struct {
game Game
updateCalled bool
offscreen *Image
screen *Image
// The following members must be protected by the mutex m.
outsideWidth float64
outsideHeight float64
screenShader *Shader
m sync.Mutex
}
func newContext(game Game) *context {
return &context{
game: game,
}
}
func (c *context) updateFrame(graphicsDriver graphicsdriver.Graphics, outsideWidth, outsideHeight float64, deviceScaleFactor float64) error {
// TODO: If updateCount is 0 and vsync is disabled, swapping buffers can be skipped.
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return c.updateFrameImpl(graphicsDriver, clock.UpdateFrame(), outsideWidth, outsideHeight, deviceScaleFactor)
}
func (c *context) forceUpdateFrame(graphicsDriver graphicsdriver.Graphics, outsideWidth, outsideHeight float64, deviceScaleFactor float64) error {
n := 1
if graphicsDriver.IsDirectX() {
// On DirectX, both framebuffers in the swap chain should be updated.
// Or, the rendering result becomes unexpected when the window is resized.
n = 2
}
for i := 0; i < n; i++ {
if err := c.updateFrameImpl(graphicsDriver, 1, outsideWidth, outsideHeight, deviceScaleFactor); err != nil {
return err
}
}
return nil
}
func (c *context) updateFrameImpl(graphicsDriver graphicsdriver.Graphics, updateCount int, outsideWidth, outsideHeight float64, deviceScaleFactor float64) (err error) {
if err := theGlobalState.error(); err != nil {
return err
}
// The given outside size can be 0 e.g. just after restoring from the fullscreen mode on Windows (#1589)
// Just ignore such cases. Otherwise, creating a zero-sized framebuffer causes a panic.
if outsideWidth == 0 || outsideHeight == 0 {
return nil
}
debug.Logf("----\n")
if err := buffered.BeginFrame(graphicsDriver); err != nil {
return err
}
defer func() {
// All the vertices data are consumed at the end of the frame, and the data backend can be
// available after that. Until then, lock the vertices backend.
err1 := graphics.LockAndResetVertices(func() error {
if err := buffered.EndFrame(graphicsDriver); err != nil {
return err
}
return nil
})
if err == nil {
err = err1
}
}()
// Create a shader for the screen if necessary.
if c.screenShader == nil {
ir, err := graphics.CompileShader([]byte(screenShader))
if err != nil {
return err
}
c.screenShader = NewShader(ir)
}
// ForceUpdate can be invoked even if the context is not initialized yet (#1591).
if w, h := c.layoutGame(outsideWidth, outsideHeight, deviceScaleFactor); w == 0 || h == 0 {
return nil
}
// Ensure that Update is called once before Draw so that Update can be used for initialization.
if !c.updateCalled && updateCount == 0 {
updateCount = 1
c.updateCalled = true
}
debug.Logf("Update count per frame: %d\n", updateCount)
// Update the game.
for i := 0; i < updateCount; i++ {
if err := hooks.RunBeforeUpdateHooks(); err != nil {
return err
}
if err := c.game.Update(); err != nil {
return err
}
// Catch the error that happened at (*Image).At.
if err := theGlobalState.error(); err != nil {
return err
}
theUI.resetForTick()
}
// Draw the game.
c.drawGame(graphicsDriver)
// All the vertices data are consumed at the end of the frame, and the data backend can be
// available after that. Until then, lock the vertices backend.
return nil
}
func (c *context) drawGame(graphicsDriver graphicsdriver.Graphics) {
if c.offscreen.volatile != theGlobalState.isScreenClearedEveryFrame() {
w, h := c.offscreen.width, c.offscreen.height
c.offscreen.MarkDisposed()
c.offscreen = c.game.NewOffscreenImage(w, h)
}
// Even though updateCount == 0, the offscreen is cleared and Draw is called.
// Draw should not update the game state and then the screen should not be updated without Update, but
// users might want to process something at Draw with the time intervals of FPS.
if theGlobalState.isScreenClearedEveryFrame() {
c.offscreen.clear()
}
c.game.Draw()
if graphicsDriver.NeedsClearingScreen() {
// This clear is needed for fullscreen mode or some mobile platforms (#622).
c.screen.clear()
}
ga := 1.0
gd := 1.0
gtx := 0.0
gty := 0.0
screenScale, offsetX, offsetY := c.screenScaleAndOffsets()
s := screenScale
switch y := graphicsDriver.FramebufferYDirection(); y {
case graphicsdriver.Upward:
ga *= s
gd *= -s
gty += float64(c.offscreen.height) * s
case graphicsdriver.Downward:
ga *= s
gd *= s
default:
panic(fmt.Sprintf("ui: invalid y-direction: %d", y))
}
gtx += offsetX
gty += offsetY
var filter graphicsdriver.Filter
var screenFilter bool
switch {
case !theGlobalState.isScreenFilterEnabled():
filter = graphicsdriver.FilterNearest
case math.Floor(s) == s:
filter = graphicsdriver.FilterNearest
case s > 1:
screenFilter = true
default:
// screenShader works with >=1 scale, but does not well with <1 scale.
// Use regular FilterLinear instead so far (#669).
filter = graphicsdriver.FilterLinear
}
dstRegion := graphicsdriver.Region{
X: 0,
Y: 0,
Width: float32(c.screen.width),
Height: float32(c.screen.height),
}
vs := graphics.QuadVertices(
0, 0, float32(c.offscreen.width), float32(c.offscreen.height),
float32(ga), 0, 0, float32(gd), float32(gtx), float32(gty),
1, 1, 1, 1)
is := graphics.QuadIndices()
srcs := [graphics.ShaderImageCount]*Image{c.offscreen}
var shader *Shader
var uniforms [][]float32
if screenFilter {
shader = c.screenShader
dstWidth := c.screen.width
srcWidth := c.offscreen.width
uniforms = shader.ConvertUniforms(map[string]interface{}{
"Scale": float32(dstWidth) / float32(srcWidth),
})
}
c.screen.DrawTriangles(srcs, vs, is, affine.ColorMIdentity{}, graphicsdriver.CompositeModeCopy, filter, graphicsdriver.AddressUnsafe, dstRegion, graphicsdriver.Region{}, [graphics.ShaderImageCount - 1][2]float32{}, shader, uniforms, false, true)
}
func (c *context) layoutGame(outsideWidth, outsideHeight float64, deviceScaleFactor float64) (int, int) {
c.m.Lock()
defer c.m.Unlock()
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c.outsideWidth = outsideWidth
c.outsideHeight = outsideHeight
ow, oh := c.game.Layout(int(outsideWidth), int(outsideHeight))
if ow <= 0 || oh <= 0 {
panic("ui: Layout must return positive numbers")
}
sw, sh := int(outsideWidth*deviceScaleFactor), int(outsideHeight*deviceScaleFactor)
if c.screen != nil {
if c.screen.width != sw || c.screen.height != sh {
c.screen.MarkDisposed()
c.screen = nil
}
}
if c.screen == nil {
c.screen = NewImage(sw, sh, atlas.ImageTypeScreen)
}
if c.offscreen != nil {
if c.offscreen.width != ow || c.offscreen.height != oh {
c.offscreen.MarkDisposed()
c.offscreen = nil
}
}
if c.offscreen == nil {
c.offscreen = c.game.NewOffscreenImage(ow, oh)
}
return ow, oh
}
func (c *context) adjustPosition(x, y float64, deviceScaleFactor float64) (float64, float64) {
s, ox, oy := c.screenScaleAndOffsets()
// The scale 0 indicates that the screen is not initialized yet.
// As any cursor values don't make sense, just return NaN.
if s == 0 {
return math.NaN(), math.NaN()
}
return (x*deviceScaleFactor - ox) / s, (y*deviceScaleFactor - oy) / s
}
func (c *context) screenScaleAndOffsets() (float64, float64, float64) {
c.m.Lock()
defer c.m.Unlock()
if c.screen == nil {
return 0, 0, 0
}
scaleX := float64(c.screen.width) / float64(c.offscreen.width)
scaleY := float64(c.screen.height) / float64(c.offscreen.height)
scale := math.Min(scaleX, scaleY)
width := float64(c.offscreen.width) * scale
height := float64(c.offscreen.height) * scale
x := (float64(c.screen.width) - width) / 2
y := (float64(c.screen.height) - height) / 2
return scale, x, y
}
var theGlobalState = globalState{
isScreenClearedEveryFrame_: 1,
screenFilterEnabled_: 1,
}
// globalState represents a global state in this package.
// This is available even before the game loop starts.
type globalState struct {
err_ error
errM sync.Mutex
fpsMode_ int32
isScreenClearedEveryFrame_ int32
screenFilterEnabled_ int32
graphicsLibrary_ int32
}
func (g *globalState) error() error {
g.errM.Lock()
defer g.errM.Unlock()
return g.err_
}
func (g *globalState) setError(err error) {
g.errM.Lock()
defer g.errM.Unlock()
if g.err_ == nil {
g.err_ = err
}
}
func (g *globalState) fpsMode() FPSModeType {
return FPSModeType(atomic.LoadInt32(&g.fpsMode_))
}
func (g *globalState) setFPSMode(fpsMode FPSModeType) {
atomic.StoreInt32(&g.fpsMode_, int32(fpsMode))
}
func (g *globalState) isScreenClearedEveryFrame() bool {
return atomic.LoadInt32(&g.isScreenClearedEveryFrame_) != 0
}
func (g *globalState) setScreenClearedEveryFrame(cleared bool) {
v := int32(0)
if cleared {
v = 1
}
atomic.StoreInt32(&g.isScreenClearedEveryFrame_, v)
}
func (g *globalState) isScreenFilterEnabled() bool {
return graphicsdriver.Filter(atomic.LoadInt32(&g.screenFilterEnabled_)) != 0
}
func (g *globalState) setScreenFilterEnabled(enabled bool) {
v := int32(0)
if enabled {
v = 1
}
atomic.StoreInt32(&g.screenFilterEnabled_, v)
}
func (g *globalState) setGraphicsLibrary(library GraphicsLibrary) {
atomic.StoreInt32(&g.graphicsLibrary_, int32(library))
}
func (g *globalState) graphicsLibrary() GraphicsLibrary {
return GraphicsLibrary(atomic.LoadInt32(&g.graphicsLibrary_))
}
func FPSMode() FPSModeType {
return theGlobalState.fpsMode()
}
func SetFPSMode(fpsMode FPSModeType) {
theGlobalState.setFPSMode(fpsMode)
theUI.SetFPSMode(fpsMode)
}
func IsScreenClearedEveryFrame() bool {
return theGlobalState.isScreenClearedEveryFrame()
}
func SetScreenClearedEveryFrame(cleared bool) {
theGlobalState.setScreenClearedEveryFrame(cleared)
}
func IsScreenFilterEnabled() bool {
return theGlobalState.isScreenFilterEnabled()
}
func SetScreenFilterEnabled(enabled bool) {
theGlobalState.setScreenFilterEnabled(enabled)
}
func GetGraphicsLibrary() GraphicsLibrary {
return theGlobalState.graphicsLibrary()
}