graphics: Detect maximum texture size for each environment

Fixes #537, #539

See also #541

graphicscontext.go

@@ -103,8 +103,8 @@ func (c *graphicsContext) Update(afterFrameUpdate func()) error {
 	if c.offsetX > 0 || c.offsetY > 0 {
 		op := &DrawImageOptions{}
 		w, h := emptyImage.Size()
-		// graphics.MaxImageSize should be the maximum size of framebuffer.
-		op.GeoM.Scale(graphics.MaxImageSize/float64(w), graphics.MaxImageSize/float64(h))
+		s := float64(graphics.MaxImageSize())
+		op.GeoM.Scale(s/float64(w), s/float64(h))
 		op.CompositeMode = CompositeModeCopy
 		c.screen.DrawImage(emptyImage, op)
 	}

image.go

@@ -552,5 +552,7 @@ func newImageWithScreenFramebuffer(width, height int) *Image {
 	return i
 }
 
-// MaxImageSize represents the maximum width/height of an image.
-const MaxImageSize = graphics.MaxImageSize
+// MaxImageSize is deprecated as of 1.7.0-alpha. No replacement so far.
+//
+// TODO: Make this replacement (#541)
+var MaxImageSize = 4096

internal/graphics/command.go

@@ -332,11 +332,12 @@ func checkSize(width, height int) {
 	if height < 1 {
 		panic(fmt.Sprintf("graphics: height (%d) must be equal or more than 1.", height))
 	}
-	if width > MaxImageSize {
-		panic(fmt.Sprintf("graphics: width (%d) must be less than or equal to %d", width, MaxImageSize))
+	m := MaxImageSize()
+	if width > m {
+		panic(fmt.Sprintf("graphics: width (%d) must be less than or equal to %d", width, m))
 	}
-	if height > MaxImageSize {
-		panic(fmt.Sprintf("graphics: height (%d) must be less than or equal to %d", height, MaxImageSize))
+	if height > m {
+		panic(fmt.Sprintf("graphics: height (%d) must be less than or equal to %d", height, m))
 	}
 }
 

internal/graphics/framebuffer.go

@@ -66,11 +66,6 @@ func newScreenFramebuffer(width, height int) *framebuffer {
 	}
 }
 
-// defaultViewportSize is the default size (width or height) of viewport.
-//
-// defaultViewportSize also represents the maximum size of a framebuffer.
-const defaultViewportSize = 4096
-
 // viewportSize returns the viewport size of the framebuffer.
 func (f *framebuffer) viewportSize() (int, int) {
 	// On some browsers, viewport size must be within the framebuffer size.
@@ -80,7 +75,8 @@ func (f *framebuffer) viewportSize() (int, int) {
 	}
 
 	// If possible, always use the same viewport size to reduce draw calls.
-	return defaultViewportSize, defaultViewportSize
+	m := MaxImageSize()
+	return m, m
 }
 
 // setAsViewport sets the framebuffer as the current viewport.

internal/graphics/image.go

@@ -18,8 +18,31 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/affine"
 	"github.com/hajimehoshi/ebiten/internal/math"
 	"github.com/hajimehoshi/ebiten/internal/opengl"
+	"github.com/hajimehoshi/ebiten/internal/sync"
 )
 
+var (
+	// maxTextureSize is the maximum texture size
+	//
+	// maxTextureSize also represents the default size (width or height) of viewport.
+	maxTextureSize     = 0
+	maxTextureSizeLock sync.Mutex
+)
+
+// MaxImageSize returns the maximum of width/height of an image.
+func MaxImageSize() int {
+	maxTextureSizeLock.Lock()
+	if maxTextureSize == 0 {
+		maxTextureSize = opengl.GetContext().MaxTextureSize()
+		if maxTextureSize == 0 {
+			panic("graphics: failed to get the max texture size")
+		}
+	}
+	s := maxTextureSize
+	maxTextureSizeLock.Unlock()
+	return s
+}
+
 // Image represents an image that is implemented with OpenGL.
 type Image struct {
 	texture     *texture
@@ -28,9 +51,6 @@ type Image struct {
 	height      int
 }
 
-// MaxImageSize is the maximum of width/height of an image.
-const MaxImageSize = defaultViewportSize
-
 func NewImage(width, height int) *Image {
 	i := &Image{
 		width:  width,

internal/graphics/program.go

@@ -147,6 +147,7 @@ func (s *openGLState) reset() error {
 	if err := opengl.GetContext().Reset(); err != nil {
 		return err
 	}
+
 	s.lastProgram = zeroProgram
 	s.lastProjectionMatrix = nil
 	s.lastColorMatrix = nil

internal/opengl/context.go

@@ -51,6 +51,7 @@ type Context struct {
 	lastViewportWidth  int
 	lastViewportHeight int
 	lastCompositeMode  CompositeMode
+	maxTextureSize     int
 	context
 }
 
@@ -93,3 +94,10 @@ func (c *Context) ResetViewportSize() {
 	c.lastViewportWidth = 0
 	c.lastViewportHeight = 0
 }
+
+func (c *Context) MaxTextureSize() int {
+	if c.maxTextureSize == 0 {
+		c.maxTextureSize = c.maxTextureSizeImpl()
+	}
+	return c.maxTextureSize
+}

internal/opengl/context_desktop.go

@@ -494,6 +494,17 @@ func (c *Context) DrawElements(mode Mode, len int, offsetInBytes int) {
 	})
 }
 
+func (c *Context) maxTextureSizeImpl() int {
+	size := 0
+	_ = c.runOnContextThread(func() error {
+		s := int32(0)
+		gl.GetIntegerv(gl.MAX_TEXTURE_SIZE, &s)
+		size = int(s)
+		return nil
+	})
+	return size
+}
+
 func (c *Context) Flush() {
 	_ = c.runOnContextThread(func() error {
 		gl.Flush()

internal/opengl/context_js.go

@@ -379,6 +379,11 @@ func (c *Context) DrawElements(mode Mode, len int, offsetInBytes int) {
 	gl.DrawElements(int(mode), len, gl.UNSIGNED_SHORT, offsetInBytes)
 }
 
+func (c *Context) maxTextureSizeImpl() int {
+	gl := c.gl
+	return gl.GetParameter(gl.MAX_TEXTURE_SIZE).Int()
+}
+
 func (c *Context) Flush() {
 	gl := c.gl
 	gl.Flush()

internal/opengl/context_mobile.go

@@ -399,6 +399,11 @@ func (c *Context) DrawElements(mode Mode, len int, offsetInBytes int) {
 	gl.DrawElements(mgl.Enum(mode), len, mgl.UNSIGNED_SHORT, offsetInBytes)
 }
 
+func (c *Context) maxTextureSizeImpl() int {
+	gl := c.gl
+	return gl.GetInteger(mgl.MAX_TEXTURE_SIZE)
+}
+
 func (c *Context) Flush() {
 	gl := c.gl
 	gl.Flush()