shareable: Don't extend textures on macOS

Fixes #593

internal/shareable/shareable.go

@@ -270,11 +270,6 @@ func (i *Image) allocate(shareable bool) {
 		panic("not reached")
 	}
 
-	const (
-		initSize = 1024
-		maxSize  = 4096
-	)
-
 	if !shareable || i.width > maxSize || i.height > maxSize {
 		i.backend = &backend{
 			restorable: restorable.NewImage(i.width, i.height, false),

internal/shareable/size_macos.go

@@ -0,0 +1,29 @@
+// Copyright 2018 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.
+
+// +build darwin
+// +build !ios
+// +build !js
+
+package shareable
+
+// On MacBook Pro 2013 (Late), there is a bug in texture rendering and
+// extending shareable textures sometimes fail (#593). This is due to
+// a bug in the grahics driver, and there is nothing we can do. Let's
+// not extend shareable textures in such environment.
+
+const (
+	initSize = 4096
+	maxSize  = 4096
+)

internal/shareable/size_notmacos.go

@@ -0,0 +1,22 @@
+// Copyright 2018 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.
+
+// +build !darwin ios js
+
+package shareable
+
+const (
+	initSize = 1024
+	maxSize  = 4096
+)