ebiten/internal/graphicsdriver/opengl/gl/procaddr_others.go

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// 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 !darwin && !js && !nintendosdk && !windows
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"
)
var (
libGL unsafe.Pointer
libGLES unsafe.Pointer
)
func (c *defaultContext) init() error {
var preferES bool
if runtime.GOOS == "android" {
preferES = true
}
if !preferES {
for _, t := range strings.Split(os.Getenv("EBITENGINE_OPENGL"), ",") {
switch strings.TrimSpace(t) {
case "es":
preferES = true
break
}
}
}
// Try OpenGL first. OpenGL is preferable as this doesn't cause context losses.
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 {
libGL = lib
return nil
}
}
}
// 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 {
libGLES = lib
c.isES = true
return nil
}
}
return fmt.Errorf("gl: failed to load libGL.so and libGLESv2.so")
}
func (c *defaultContext) getProcAddress(name string) (uintptr, error) {
if c.isES {
return getProcAddressGLES(name), nil
}
return getProcAddressGL(name), nil
}
func getProcAddressGL(name string) uintptr {
cname := C.CString(name)
defer C.free(unsafe.Pointer(cname))
return uintptr(C.getProcAddressGL(libGL, cname))
}
func getProcAddressGLES(name string) uintptr {
cname := C.CString(name)
defer C.free(unsafe.Pointer(cname))
return uintptr(C.getProcAddressGLES(libGLES, cname))
}