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 (
"math"
"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/graphicsdriver"
"github.com/hajimehoshi/ebiten/v2/internal/hooks"
"github.com/hajimehoshi/ebiten/v2/internal/mipmap"
)
var (
NearestFilterShader = &Shader{shader: mipmap.NearestFilterShader}
LinearFilterShader = &Shader{shader: mipmap.LinearFilterShader}
)
type Game interface {
NewOffscreenImage(width, height int) *Image
NewScreenImage(width, height int) *Image
Layout(outsideWidth, outsideHeight float64) (screenWidth, screenHeight float64)
UpdateInputState(InputState)
Update() error
DrawOffscreen() error
DrawFinalScreen(scale, offsetX, offsetY float64)
}
type context struct {
game Game
updateCalled bool
offscreen *Image
screen *Image
screenWidth float64
screenHeight float64
offscreenWidth float64
offscreenHeight float64
isOffscreenModified bool
skipCount int
}
func newContext(game Game) *context {
return &context{
game: game,
}
}
func (c *context) updateFrame(graphicsDriver graphicsdriver.Graphics, outsideWidth, outsideHeight float64, deviceScaleFactor float64, ui *userInterfaceImpl) error {
// TODO: If updateCount is 0 and vsync is disabled, swapping buffers can be skipped.
return c.updateFrameImpl(graphicsDriver, clock.UpdateFrame(), outsideWidth, outsideHeight, deviceScaleFactor, ui, false)
}
func (c *context) forceUpdateFrame(graphicsDriver graphicsdriver.Graphics, outsideWidth, outsideHeight float64, deviceScaleFactor float64, ui *userInterfaceImpl) 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, ui, true); err != nil {
return err
}
}
return nil
}
func (c *context) updateFrameImpl(graphicsDriver graphicsdriver.Graphics, updateCount int, outsideWidth, outsideHeight float64, deviceScaleFactor float64, ui *userInterfaceImpl, forceDraw bool) (err error) {
if err := theGlobalState.error(); err != nil {
return err
}
ui.beginFrame()
defer ui.endFrame()
// 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() {
if err1 := buffered.EndFrame(graphicsDriver); err == nil && err1 != nil {
err = err1
}
}()
// 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++ {
// Read the input state and use it for one tick to give a consistent result for one tick (#2496, #2501).
var inputState InputState
ui.readInputState(&inputState)
c.game.UpdateInputState(inputState)
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
}
ui.resetForTick()
}
// Draw the game.
if err := c.drawGame(graphicsDriver, forceDraw); err != nil {
return err
}
return nil
}
func (c *context) drawGame(graphicsDriver graphicsdriver.Graphics, forceDraw bool) error {
if (c.offscreen.imageType == atlas.ImageTypeVolatile) != theGlobalState.isScreenClearedEveryFrame() {
w, h := c.offscreen.width, c.offscreen.height
c.offscreen.MarkDisposed()
c.offscreen = c.game.NewOffscreenImage(w, h)
}
// isOffscreenModified is updated when an offscreen's modifyCallback.
c.isOffscreenModified = false
// 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()
}
if err := c.game.DrawOffscreen(); err != nil {
return err
}
// 180 might be too big but this is a enough value to consider exiting from fullscreen on macOS (#2500).
const maxSkipCount = 180
if !forceDraw && !c.isOffscreenModified {
if c.skipCount < maxSkipCount {
c.skipCount++
}
} else {
c.skipCount = 0
}
// If the offscreen is not updated and the framebuffers don't have to be updated, skip rendering to save GPU power.
if c.skipCount < maxSkipCount {
if graphicsDriver.NeedsClearingScreen() {
// This clear is needed for fullscreen mode or some mobile platforms (#622).
c.screen.clear()
}
c.game.DrawFinalScreen(c.screenScaleAndOffsets())
// The final screen is never used as the rendering source.
// Flush its buffer here just in case.
c.screen.flushBufferIfNeeded()
}
return nil
}
func (c *context) layoutGame(outsideWidth, outsideHeight float64, deviceScaleFactor float64) (int, int) {
owf, ohf := c.game.Layout(outsideWidth, outsideHeight)
if owf <= 0 || ohf <= 0 {
panic("ui: Layout must return positive numbers")
}
c.screenWidth = outsideWidth * deviceScaleFactor
c.screenHeight = outsideHeight * deviceScaleFactor
c.offscreenWidth = owf
c.offscreenHeight = ohf
sw := int(math.Ceil(c.screenWidth))
sh := int(math.Ceil(c.screenHeight))
ow := int(math.Ceil(c.offscreenWidth))
oh := int(math.Ceil(c.offscreenHeight))
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 = c.game.NewScreenImage(sw, sh)
}
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)
c.offscreen.modifyCallback = func() {
c.isOffscreenModified = true
}
}
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() (scale, offsetX, offsetY float64) {
scaleX := c.screenWidth / c.offscreenWidth
scaleY := c.screenHeight / c.offscreenHeight
scale = math.Min(scaleX, scaleY)
width := c.offscreenWidth * scale
height := c.offscreenHeight * scale
offsetX = (c.screenWidth - width) / 2
offsetY = (c.screenHeight - height) / 2
return
}