internal/graphicsdriver/gl: use PureGo for Linux and UNIX

Updates #2284

go.mod

@@ -6,7 +6,7 @@ require (
 	github.com/ebitengine/gomobile v0.0.0-20240329170434-1771503ff0a8
 	github.com/ebitengine/hideconsole v1.0.0
 	github.com/ebitengine/oto/v3 v3.3.0-alpha.1
-	github.com/ebitengine/purego v0.8.0-alpha.0.20240404024320-d0aedd0f4393
+	github.com/ebitengine/purego v0.8.0-alpha.0.20240407111646-0e6302132b78
 	github.com/go-text/typesetting v0.1.1-0.20240402181327-ced1d6822703
 	github.com/hajimehoshi/bitmapfont/v3 v3.0.0
 	github.com/hajimehoshi/go-mp3 v0.3.4

go.sum

@@ -4,8 +4,8 @@ github.com/ebitengine/hideconsole v1.0.0 h1:5J4U0kXF+pv/DhiXt5/lTz0eO5ogJ1iXb8Yj
 github.com/ebitengine/hideconsole v1.0.0/go.mod h1:hTTBTvVYWKBuxPr7peweneWdkUwEuHuB3C1R/ielR1A=
 github.com/ebitengine/oto/v3 v3.3.0-alpha.1 h1:J2nBmQwPLKc4+yLObytq1jKNydI96l6EjZfgefiqGbk=
 github.com/ebitengine/oto/v3 v3.3.0-alpha.1/go.mod h1:T2/VV0UWG97GEEf4kORMU2nCneYT/YmwSTxPutSVaUg=
-github.com/ebitengine/purego v0.8.0-alpha.0.20240404024320-d0aedd0f4393 h1:8mFaXjlt/DLC5MlrnsR71EpK196kVYvPTC2soh06rGU=
-github.com/ebitengine/purego v0.8.0-alpha.0.20240404024320-d0aedd0f4393/go.mod h1:y8L+ZRLphbdPW2xs41fur/KaW57yTzrFsqsclHyHrTM=
+github.com/ebitengine/purego v0.8.0-alpha.0.20240407111646-0e6302132b78 h1:9uNVUYEdJkmroySbiQL0sfhZvCYeZaF3os6WuLY1PEQ=
+github.com/ebitengine/purego v0.8.0-alpha.0.20240407111646-0e6302132b78/go.mod h1:y8L+ZRLphbdPW2xs41fur/KaW57yTzrFsqsclHyHrTM=
 github.com/go-text/typesetting v0.1.1-0.20240402181327-ced1d6822703 h1:AqtMl9yw7r319Ah4W2afQm3Ql+PEsQKHds18tGvKhog=
 github.com/go-text/typesetting v0.1.1-0.20240402181327-ced1d6822703/go.mod h1:2+owI/sxa73XA581LAzVuEBZ3WEEV2pXeDswCH/3i1I=
 github.com/go-text/typesetting-utils v0.0.0-20240317173224-1986cbe96c66 h1:GUrm65PQPlhFSKjLPGOZNPNxLCybjzjYBzjfoBGaDUY=

internal/graphicsdriver/opengl/gl/default_cgo.go

@@ -2,7 +2,7 @@
 // SPDX-FileCopyrightText: 2014 Eric Woroshow
 // SPDX-FileCopyrightText: 2022 The Ebitengine Authors
 
-//go:build !darwin && !js && !windows && !playstation5
+//go:build nintendosdk
 
 package gl
 

internal/graphicsdriver/opengl/gl/default_purego.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build darwin || windows
+//go:build (darwin || freebsd || linux || netbsd || openbsd || windows) && !nintendosdk && !playstation5
 
 package gl
 

internal/graphicsdriver/opengl/gl/procaddr_linbsd.go

@@ -16,38 +16,18 @@
 
 package gl
 
-// #cgo LDFLAGS: -ldl
-//
-// #include <dlfcn.h>
-// #include <stdlib.h>
-//
-// static void* getProcAddressGL(void* libGL, const char* name) {
-//   static void*(*glXGetProcAddress)(const char*);
-//   if (!glXGetProcAddress) {
-//     glXGetProcAddress = dlsym(libGL, "glXGetProcAddress");
-//     if (!glXGetProcAddress) {
-//       glXGetProcAddress = dlsym(libGL, "glXGetProcAddressARB");
-//     }
-//   }
-//   return glXGetProcAddress(name);
-// }
-//
-// static void* getProcAddressGLES(void* libGLES, const char* name) {
-//   return dlsym(libGLES, name);
-// }
-import "C"
-
 import (
 	"fmt"
 	"os"
 	"runtime"
 	"strings"
-	"unsafe"
+
+	"github.com/ebitengine/purego"
 )
 
 var (
-	libGL   unsafe.Pointer
-	libGLES unsafe.Pointer
+	libGL   uintptr
+	libGLES uintptr
 )
 
 func (c *defaultContext) init() error {
@@ -69,10 +49,8 @@ func (c *defaultContext) init() error {
 	if !preferES {
 		// Usually libGL.so or libGL.so.1 is used. libGL.so.2 might exist only on NetBSD.
 		for _, name := range []string{"libGL.so", "libGL.so.2", "libGL.so.1", "libGL.so.0"} {
-			cname := C.CString(name)
-			lib := C.dlopen(cname, C.RTLD_LAZY|C.RTLD_GLOBAL)
-			C.free(unsafe.Pointer(cname))
-			if lib != nil {
+			lib, err := purego.Dlopen(name, purego.RTLD_LAZY|purego.RTLD_GLOBAL)
+			if err == nil {
 				libGL = lib
 				return nil
 			}
@@ -81,10 +59,8 @@ func (c *defaultContext) init() error {
 
 	// Try OpenGL ES.
 	for _, name := range []string{"libGLESv2.so", "libGLESv2.so.2", "libGLESv2.so.1", "libGLESv2.so.0"} {
-		cname := C.CString(name)
-		lib := C.dlopen(cname, C.RTLD_LAZY|C.RTLD_GLOBAL)
-		C.free(unsafe.Pointer(cname))
-		if lib != nil {
+		lib, err := purego.Dlopen(name, purego.RTLD_LAZY|purego.RTLD_GLOBAL)
+		if err == nil {
 			libGLES = lib
 			c.isES = true
 			return nil
@@ -96,19 +72,32 @@ func (c *defaultContext) init() error {
 
 func (c *defaultContext) getProcAddress(name string) (uintptr, error) {
 	if c.isES {
-		return getProcAddressGLES(name), nil
+		return getProcAddressGLES(name)
 	}
-	return getProcAddressGL(name), nil
+	return getProcAddressGL(name)
 }
 
-func getProcAddressGL(name string) uintptr {
-	cname := C.CString(name)
-	defer C.free(unsafe.Pointer(cname))
-	return uintptr(C.getProcAddressGL(libGL, cname))
+var glXGetProcAddress func(name string) uintptr
+
+func getProcAddressGL(name string) (uintptr, error) {
+	if glXGetProcAddress == nil {
+		if _, err := purego.Dlsym(libGL, "glXGetProcAddress"); err == nil {
+			purego.RegisterLibFunc(&glXGetProcAddress, libGL, "glXGetProcAddress")
+		} else if _, err := purego.Dlsym(libGL, "glXGetProcAddressARB"); err == nil {
+			purego.RegisterLibFunc(&glXGetProcAddress, libGL, "glXGetProcAddressARB")
+		}
+	}
+	if glXGetProcAddress == nil {
+		return 0, fmt.Errorf("gl: failed to find glXGetProcAddress or glXGetProcAddressARB in libGL.so")
+	}
+
+	return glXGetProcAddress(name), nil
 }
 
-func getProcAddressGLES(name string) uintptr {
-	cname := C.CString(name)
-	defer C.free(unsafe.Pointer(cname))
-	return uintptr(C.getProcAddressGLES(libGLES, cname))
+func getProcAddressGLES(name string) (uintptr, error) {
+	proc, err := purego.Dlsym(libGLES, name)
+	if err != nil {
+		return 0, err
+	}
+	return proc, nil
 }