internal/graphicsdriver/opengl/gl: reland: refactoring: reduce opengles build tags

This is a reland of c9cff69dcb.

Updates #292

internal/graphicsdriver/opengl/context_js.go

@@ -608,3 +608,8 @@ func (c *context) endStencilWithEvenOddRule() {
 	c.gl.stencilOp.Invoke(gl.KEEP, gl.KEEP, gl.KEEP)
 	c.gl.colorMask.Invoke(true, true, true, true)
 }
+
+func (c *context) isES() bool {
+	// WebGL is compatible with GLES.
+	return true
+}

internal/graphicsdriver/opengl/context_notjs.go

@@ -477,3 +477,7 @@ func (c *context) endStencilWithEvenOddRule() {
 	c.ctx.StencilOp(gl.KEEP, gl.KEEP, gl.KEEP)
 	c.ctx.ColorMask(true, true, true, true)
 }
+
+func (c *context) isES() bool {
+	return c.ctx.IsES()
+}

internal/graphicsdriver/opengl/gl/default_android.go

@@ -41,6 +41,10 @@ func (defaultContext) Init() error {
 	return nil
 }
 
+func (defaultContext) IsES() bool {
+	return true
+}
+
 func (defaultContext) ActiveTexture(texture uint32) {
 	C.glActiveTexture(C.GLenum(texture))
 }

internal/graphicsdriver/opengl/gl/default_notpurego.go

@@ -406,6 +406,10 @@ func boolToInt(b bool) int {
 	return 0
 }
 
+func (c *defaultContext) IsES() bool {
+	return isES
+}
+
 func (c *defaultContext) ActiveTexture(texture uint32) {
 	C.glowActiveTexture(c.gpActiveTexture, (C.GLenum)(texture))
 }

internal/graphicsdriver/opengl/gl/default_purego.go

@@ -107,6 +107,10 @@ func boolToInt(b bool) int {
 	return 0
 }
 
+func (c *defaultContext) IsES() bool {
+	return isES
+}
+
 func (c *defaultContext) ActiveTexture(texture uint32) {
 	purego.SyscallN(c.gpActiveTexture, uintptr(texture))
 }

internal/graphicsdriver/opengl/gl/gomobile.go

@@ -39,6 +39,10 @@ func (g *gomobileContext) Init() error {
 	return nil
 }
 
+func (g *gomobileContext) IsES() bool {
+	return true
+}
+
 func (g *gomobileContext) ActiveTexture(texture uint32) {
 	g.ctx.ActiveTexture(gl.Enum(texture))
 }

internal/graphicsdriver/opengl/gl/interface.go

@@ -20,6 +20,7 @@ package gl
 // See https://pkg.go.dev/golang.org/x/mobile/gl#Context
 type Context interface {
 	Init() error
+	IsES() bool
 
 	ActiveTexture(texture uint32)
 	AttachShader(program uint32, shader uint32)

internal/graphicsdriver/opengl/gl/procaddr_darwin.go

@@ -18,11 +18,15 @@ import (
 	"github.com/ebitengine/purego"
 )
 
-var opengl uintptr
+var (
+	opengl uintptr
+	isES   bool
+)
 
 func init() {
 	opengl = purego.Dlopen("/System/Library/Frameworks/OpenGLES.framework/Versions/Current/OpenGLES", purego.RTLD_GLOBAL)
 	if opengl != 0 {
+		isES = true
 		return
 	}
 	opengl = purego.Dlopen("/System/Library/Frameworks/OpenGL.framework/Versions/Current/OpenGL", purego.RTLD_GLOBAL)

internal/graphicsdriver/opengl/gl/procaddr_gl.go

@@ -28,6 +28,8 @@ import "C"
 
 import "unsafe"
 
+var isES = false
+
 func getProcAddress(namea string) unsafe.Pointer {
 	cname := C.CString(namea)
 	defer C.free(unsafe.Pointer(cname))

internal/graphicsdriver/opengl/gl/procaddr_gles.go

@@ -35,6 +35,8 @@ import (
 	"unsafe"
 )
 
+var isES = true
+
 func getProcAddress(namea string) unsafe.Pointer {
 	const ext = "EXT"
 	if strings.HasSuffix(namea, ext) {

internal/graphicsdriver/opengl/gl/procaddr_nintendosdk.go

@@ -28,6 +28,8 @@ import "C"
 
 import "unsafe"
 
+var isES = false
+
 func getProcAddress(namea string) unsafe.Pointer {
 	cname := C.CString(namea)
 	defer C.free(unsafe.Pointer(cname))

internal/graphicsdriver/opengl/gl/procaddr_windows.go

@@ -24,6 +24,7 @@ import (
 var (
 	opengl32              = windows.NewLazySystemDLL("opengl32")
 	procWglGetProcAddress = opengl32.NewProc("wglGetProcAddress")
+	isES                  = false
 )
 
 func getProcAddress(namea string) uintptr {

internal/graphicsdriver/opengl/graphics.go

@@ -16,6 +16,7 @@ package opengl
 
 import (
 	"fmt"
+	"runtime"
 
 	"github.com/hajimehoshi/ebiten/v2/internal/graphics"
 	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver"
@@ -265,7 +266,11 @@ func (g *Graphics) SetFullscreen(fullscreen bool) {
 }
 
 func (g *Graphics) NeedsRestoring() bool {
-	return needsRestoring
+	// Though it is possible to have a logic to restore the graphics data for GPU, do not use it for performance (#1603).
+	if runtime.GOOS == "js" {
+		return false
+	}
+	return g.context.isES()
 }
 
 func (g *Graphics) NeedsClearingScreen() bool {

internal/graphicsdriver/opengl/needsrestoring_gles.go

@@ -1,21 +0,0 @@
-// Copyright 2022 The Ebitengine 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.
-
-//go:build !android && !ios && !opengles
-
-package opengl
-
-// Though it is possible to have a logic to restore the graphics data for GPU, do not use it for performance (#1603).
-
-const needsRestoring = false

internal/graphicsdriver/opengl/needsrestoring_notgles.go

@@ -1,19 +0,0 @@
-// Copyright 2022 The Ebitengine 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.
-
-//go:build android || ios || opengles
-
-package opengl
-
-const needsRestoring = true