graphics: Fix viewport sizes for Edge (#71)

internal/graphics/command.go

@@ -381,6 +381,8 @@ func (c *newScreenFramebufferImageCommand) Exec(indexOffsetInBytes int) error {
 	f := &framebuffer{
 		native:  opengl.GetContext().ScreenFramebuffer(),
 		flipY:   true,
+		width:   c.width,
+		height:  c.height,
 		offsetX: c.offsetX,
 		offsetY: c.offsetY,
 	}

internal/graphics/framebuffer.go

@@ -16,6 +16,7 @@ package graphics
 
 import (
 	"github.com/hajimehoshi/ebiten/internal/opengl"
+	"github.com/hajimehoshi/ebiten/internal/web"
 )
 
 func orthoProjectionMatrix(left, right, bottom, top int) []float32 {
@@ -36,39 +37,50 @@ type framebuffer struct {
 	native    opengl.Framebuffer
 	flipY     bool
 	proMatrix []float32
+	width     int
+	height    int
 	offsetX   float64
 	offsetY   float64
 }
 
-func newFramebufferFromTexture(texture *texture) (*framebuffer, error) {
+func newFramebufferFromTexture(texture *texture, width, height int) (*framebuffer, error) {
 	native, err := opengl.GetContext().NewFramebuffer(opengl.Texture(texture.native))
 	if err != nil {
 		return nil, err
 	}
 	return &framebuffer{
 		native: native,
+		width:  width,
+		height: height,
 	}, nil
 }
 
-const viewportSize = 4096
+const defaultViewportSize = 4096
+
+func (f *framebuffer) viewportSize() (int, int) {
+	if web.IsEdgeBrowser() {
+		return f.width, f.height
+	}
+	return defaultViewportSize, defaultViewportSize
+}
 
 func (f *framebuffer) setAsViewport() error {
-	width := viewportSize
-	height := viewportSize
-	return opengl.GetContext().SetViewport(f.native, width, height)
+	w, h := f.viewportSize()
+	return opengl.GetContext().SetViewport(f.native, w, h)
 }
 
 func (f *framebuffer) projectionMatrix(height int) []float32 {
 	if f.proMatrix != nil {
 		return f.proMatrix
 	}
-	m := orthoProjectionMatrix(0, viewportSize, 0, viewportSize)
+	w, h := f.viewportSize()
+	m := orthoProjectionMatrix(0, w, 0, h)
 	if f.flipY {
 		m[4*1+1] *= -1
-		m[4*3+1] += float32(height) / float32(viewportSize) * 2
+		m[4*3+1] += float32(height) / float32(h) * 2
 	}
-	m[4*3+0] += float32(f.offsetX) / float32(viewportSize) * 2
-	m[4*3+1] += float32(f.offsetY) / float32(viewportSize) * 2
+	m[4*3+0] += float32(f.offsetX) / float32(w) * 2
+	m[4*3+1] += float32(f.offsetY) / float32(h) * 2
 	f.proMatrix = m
 	return f.proMatrix
 }

internal/graphics/image.go

@@ -29,7 +29,7 @@ type Image struct {
 	height      int
 }
 
-const MaxImageSize = viewportSize
+const MaxImageSize = defaultViewportSize
 
 func NewImage(width, height int, filter opengl.Filter) *Image {
 	i := &Image{
@@ -132,7 +132,7 @@ func (i *Image) createFramebufferIfNeeded() (*framebuffer, error) {
 	if i.framebuffer != nil {
 		return i.framebuffer, nil
 	}
-	f, err := newFramebufferFromTexture(i.texture)
+	f, err := newFramebufferFromTexture(i.texture, math.NextPowerOf2Int(i.width), math.NextPowerOf2Int(i.height))
 	if err != nil {
 		return nil, err
 	}