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@ -32,6 +32,8 @@
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/* static */ OpenGLBackend *OpenGLBackend::instance = nullptr;
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GetOGLProcAddressProc GetOGLProcAddress;
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/**
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* Find a substring in a string made of space delimited elements. The substring
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* has to match the complete element, partial matches don't count.
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@ -65,7 +67,31 @@ static const char *FindStringInExtensionList(const char *string, const char *sub
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*/
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static bool IsOpenGLExtensionSupported(const char *extension)
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{
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return FindStringInExtensionList((const char *)glGetString(GL_EXTENSIONS), extension) != nullptr;
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static PFNGLGETSTRINGIPROC glGetStringi = nullptr;
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static bool glGetStringi_loaded = false;
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/* Starting with OpenGL 3.0 the preferred API to get the extensions
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* has changed. Try to load the required function once. */
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if (!glGetStringi_loaded) {
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if (IsOpenGLVersionAtLeast(3, 0)) glGetStringi = (PFNGLGETSTRINGIPROC)GetOGLProcAddress("glGetStringi");
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glGetStringi_loaded = true;
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}
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if (glGetStringi != nullptr) {
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/* New style: Each supported extension can be queried and compared independently. */
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GLint num_exts;
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glGetIntegerv(GL_NUM_EXTENSIONS, &num_exts);
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for (GLint i = 0; i < num_exts; i++) {
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const char *entry = (const char *)glGetStringi(GL_EXTENSIONS, i);
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if (strcmp(entry, extension) == 0) return true;
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}
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} else {
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/* Old style: A single, space-delimited string for all extensions. */
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return FindStringInExtensionList((const char *)glGetString(GL_EXTENSIONS), extension) != nullptr;
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}
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return false;
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}
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static byte _gl_major_ver = 0; ///< Major OpenGL version.
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@ -78,7 +104,7 @@ static byte _gl_minor_ver = 0; ///< Minor OpenGL version.
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* @pre OpenGL was initialized.
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* @return True if the OpenGL version is equal or higher than the requested one.
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*/
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static bool IsOpenGLVersionAtLeast(byte major, byte minor)
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bool IsOpenGLVersionAtLeast(byte major, byte minor)
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{
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return (_gl_major_ver > major) || (_gl_major_ver == major && _gl_minor_ver >= minor);
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}
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@ -86,11 +112,15 @@ static bool IsOpenGLVersionAtLeast(byte major, byte minor)
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/**
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* Create and initialize the singleton back-end class.
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* @param get_proc Callback to get an OpenGL function from the OS driver.
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* @return nullptr on success, error message otherwise.
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*/
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/* static */ const char *OpenGLBackend::Create()
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/* static */ const char *OpenGLBackend::Create(GetOGLProcAddressProc get_proc)
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{
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if (OpenGLBackend::instance != nullptr) OpenGLBackend::Destroy();
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GetOGLProcAddress = get_proc;
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OpenGLBackend::instance = new OpenGLBackend();
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return OpenGLBackend::instance->Init();
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}
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