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/* opengl.cpp
Copyright (c) 2014 by Michael Zahniser
Endless Sky is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later version.
Endless Sky is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "opengl.h"
#if !defined(__APPLE__) && !defined(ES_GLES)
#ifdef _WIN32
#include <GL/wglew.h>
#else
#include <GL/glxew.h>
#endif
#endif
#include <cstring>
#if defined(ES_GLES) || defined(_WIN32)
namespace {
bool HasOpenGLExtension(const char *name)
{
#ifndef __APPLE__
auto extensions = reinterpret_cast<const char *>(glGetString(GL_EXTENSIONS));
return strstr(extensions, name);
#else
bool value = false;
GLint extensionCount = 0;
glGetIntegerv(GL_NUM_EXTENSIONS, &extensionCount);
for(GLint i = 0; i < extensionCount && !value; ++i)
{
auto extension = reinterpret_cast<const char *>(glGetStringi(GL_EXTENSIONS, i));
value = (extension && strstr(extension, name));
}
return value;
#endif
}
}
#endif
bool OpenGL::HasAdaptiveVSyncSupport()
{
#ifdef __APPLE__
// macOS doesn't support Adaptive VSync for OpenGL.
return false;
#elif defined(ES_GLES)
return HasOpenGLExtension("_swap_control_tear");
#elif defined(_WIN32)
return WGL_EXT_swap_control_tear || HasOpenGLExtension("_swap_control_tear");
#else
return GLX_EXT_swap_control_tear;
#endif
}
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