ebiten/internal/graphicsdriver/opengl/gl/procaddr_linbsd.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 (freebsd || linux || netbsd || openbsd) && !nintendosdk && !playstation5
package gl
import (
"fmt"
"os"
"runtime"
"strings"
"github.com/ebitengine/purego"
)
var (
libGL uintptr
libGLES uintptr
)
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.
// TODO: Should "libOpenGL.so.0" [1] and "libGLX.so.0" [2] be added? These were added as of GLFW 3.3.9.
// [1] https://github.com/glfw/glfw/commit/55aad3c37b67f17279378db52da0a3ab81bbf26d
// [2] https://github.com/glfw/glfw/commit/c18851f52ec9704eb06464058a600845ec1eada1
for _, name := range []string{"libGL.so", "libGL.so.2", "libGL.so.1", "libGL.so.0"} {
lib, err := purego.Dlopen(name, purego.RTLD_LAZY|purego.RTLD_GLOBAL)
if err == nil {
libGL = lib
return nil
}
}
}
// Try OpenGL ES.
for _, name := range []string{"libGLESv2.so", "libGLESv2.so.2", "libGLESv2.so.1", "libGLESv2.so.0"} {
lib, err := purego.Dlopen(name, purego.RTLD_LAZY|purego.RTLD_GLOBAL)
if err == 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)
}
return getProcAddressGL(name)
}
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, error) {
proc, err := purego.Dlsym(libGLES, name)
if err != nil {
return 0, err
}
return proc, nil
}