internal/graphicsdriver/opengl: add opengles build tag

This enables to use OpenGL ES instead of OpenGL.

Closes #292

.github/workflows/test.yml

@@ -143,6 +143,12 @@ jobs:
           sudo apt-get install libasound2-dev:i386 libgl1-mesa-dev:i386 libxcursor-dev:i386 libxi-dev:i386 libxinerama-dev:i386 libxrandr-dev:i386 libxxf86vm-dev:i386
           env CGO_ENABLED=1 GOARCH=386 go test -tags=example ${{ !startsWith(matrix.go, '1.16.') && '-shuffle=on' || '' }} -v ./...
 
+      - name: go test (Linux OpenGL ES)
+        if: ${{ startsWith(matrix.os, 'ubuntu-') }}
+        run: |
+          sudo apt-get install libgles2-mesa-dev
+          env EBITENGINE_GRAPHICS_LIBRARY=opengl go test -tags=example,opengles ${{ !startsWith(matrix.go, '1.16.') && '-shuffle=on' || '' }} -v ./...
+
       - name: go test (Windows 386)
         if: ${{ startsWith(matrix.os, 'windows-') }}
         run: |

doc.go

@@ -99,4 +99,6 @@
 // `microsoftgdk` is for Microsoft GDK (e.g. Xbox).
 //
 // `nintendosdk` is for NintendoSDK (e.g. Nintendo Switch).
+//
+// `opengles` uses OpenGL ES (2) instead of OpenGL.
 package ebiten

internal/glfw/const.go

@@ -85,6 +85,7 @@ const (
 	CursorNormal   = 0x00034001
 	NoAPI          = 0
 	OpenGLAPI      = 0x00030001
+	OpenGLESAPI    = 0x00030002
 )
 
 const (

internal/graphicsdriver/opengl/bytes.go

@@ -12,9 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build android || ios
-// +build android ios
-
 package opengl
 
 import (

internal/graphicsdriver/opengl/context_gl.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build !android && !ios && !js
-// +build !android,!ios,!js
+//go:build !android && !ios && !js && !opengles
+// +build !android,!ios,!js,!opengles
 
 package opengl
 

internal/graphicsdriver/opengl/context_gles.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build android || ios
-// +build android ios
+//go:build android || ios || opengles
+// +build android ios opengles
 
 package opengl
 

internal/graphicsdriver/opengl/gles/default.go

@@ -12,25 +12,26 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build android || ios
-// +build android ios
+//go:build android || ios || opengles
+// +build android ios opengles
 
 package gles
 
-// #cgo android CFLAGS:  -Dos_android
+// #cgo !darwin          CFLAGS:     -Dos_notdarwin
+// #cgo darwin           CFLAGS:     -Dos_darwin
+// #cgo !android,!darwin pkg-config: glesv2
 // #cgo android          LDFLAGS:    -lGLESv2
-// #cgo ios     CFLAGS:  -Dos_ios
-// #cgo ios     LDFLAGS: -framework OpenGLES
+// #cgo darwin           LDFLAGS:    -framework OpenGLES
 //
-// #if defined(os_android)
-//   #include <GLES2/gl2.h>
-// #endif
-//
-// #if defined(os_ios)
+// #if defined(os_darwin)
 //   #define GLES_SILENCE_DEPRECATION
 //   #include <OpenGLES/ES2/glext.h>
 // #endif
 //
+// #if defined(os_notdarwin)
+//   #include <GLES2/gl2.h>
+// #endif
+//
 // #include <stdlib.h>
 import "C"
 

internal/graphicsdriver/opengl/gles/interface.go

@@ -12,9 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build android || ios
-// +build android ios
-
 package gles
 
 type Context interface {

internal/graphicsdriver/opengl/gles/str.go

@@ -12,9 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build android || ios
-// +build android ios
-
 package gles
 
 // #include <stdlib.h>

internal/graphicsdriver/opengl/graphics_gl.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build !android && !ios
-// +build !android,!ios
+//go:build !android && !ios && !opengles
+// +build !android,!ios,!opengles
 
 package opengl
 

internal/graphicsdriver/opengl/graphics_gles.go

@@ -0,0 +1,26 @@
+// 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
+// +build android ios opengles
+
+package opengl
+
+import (
+	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver/opengl/gles"
+)
+
+func (g *Graphics) init() {
+	g.context.ctx = gles.DefaultContext{}
+}

internal/graphicsdriver/opengl/graphics_mobile.go

@@ -23,10 +23,6 @@ import (
 	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver/opengl/gles"
 )
 
-func (g *Graphics) init() {
-	g.context.ctx = gles.DefaultContext{}
-}
-
 func (g *Graphics) SetGomobileGLContext(context gl.Context) {
 	g.context.ctx = gles.NewGomobileContext(context)
 }

internal/graphicsdriver/opengl/shader_gl.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build !android && !ios && !js
-// +build !android,!ios,!js
+//go:build !android && !ios && !js && !opengles
+// +build !android,!ios,!js,!opengles
 
 package opengl
 

internal/graphicsdriver/opengl/shader_gles.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build android || ios
-// +build android ios
+//go:build android || ios || opengles
+// +build android ios opengles
 
 package opengl
 

internal/ui/ui_glfw.go

@@ -896,9 +896,7 @@ func (u *userInterfaceImpl) init() error {
 	u.graphicsDriver.SetTransparent(u.isInitScreenTransparent())
 
 	if u.graphicsDriver.IsGL() {
-		glfw.WindowHint(glfw.ClientAPI, glfw.OpenGLAPI)
-		glfw.WindowHint(glfw.ContextVersionMajor, 2)
-		glfw.WindowHint(glfw.ContextVersionMinor, 1)
+		setGLFWClientAPI()
 	} else {
 		glfw.WindowHint(glfw.ClientAPI, glfw.NoAPI)
 	}

internal/ui/ui_glfw_gl.go

@@ -0,0 +1,28 @@
+// 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 && !js && !nintendosdk && !opengles
+// +build !android,!ios,!js,!nintendosdk,!opengles
+
+package ui
+
+import (
+	"github.com/hajimehoshi/ebiten/v2/internal/glfw"
+)
+
+func setGLFWClientAPI() {
+	glfw.WindowHint(glfw.ClientAPI, glfw.OpenGLAPI)
+	glfw.WindowHint(glfw.ContextVersionMajor, 2)
+	glfw.WindowHint(glfw.ContextVersionMinor, 1)
+}

internal/ui/ui_glfw_gles.go

@@ -0,0 +1,28 @@
+// 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 && !js && !nintendosdk && opengles
+// +build !android,!ios,!js,!nintendosdk,opengles
+
+package ui
+
+import (
+	"github.com/hajimehoshi/ebiten/v2/internal/glfw"
+)
+
+func setGLFWClientAPI() {
+	glfw.WindowHint(glfw.ClientAPI, glfw.OpenGLESAPI)
+	glfw.WindowHint(glfw.ContextVersionMajor, 2)
+	glfw.WindowHint(glfw.ContextVersionMinor, 0)
+}