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Allow re-creation of the shared context as a core context #1443

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merged 1 commit into from
Oct 23, 2018
Merged

Allow re-creation of the shared context as a core context #1443

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132 changes: 88 additions & 44 deletions src/SFML/Window/GlContext.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -212,6 +212,55 @@ namespace
// Supported OpenGL extensions
std::vector<std::string> extensions;

// Load our extensions vector with the supported extensions
void loadExtensions()
{
extensions.clear();

// Check whether a >= 3.0 context is available
int majorVersion = 0;
glGetIntegerv(GL_MAJOR_VERSION, &majorVersion);

if (glGetError() == GL_INVALID_ENUM)
{
// Try to load the < 3.0 way
const char* extensionString = reinterpret_cast<const char*>(glGetString(GL_EXTENSIONS));

do
{
const char* extension = extensionString;

while (*extensionString && (*extensionString != ' '))
extensionString++;

extensions.push_back(std::string(extension, extensionString));
}
while (*extensionString++);
}
else
{
// Try to load the >= 3.0 way
glGetStringiFuncType glGetStringiFunc = NULL;
glGetStringiFunc = reinterpret_cast<glGetStringiFuncType>(sf::priv::GlContext::getFunction("glGetStringi"));

if (glGetStringiFunc)
{
int numExtensions = 0;
glGetIntegerv(GL_NUM_EXTENSIONS, &numExtensions);

if (numExtensions)
{
for (unsigned int i = 0; i < static_cast<unsigned int>(numExtensions); ++i)
{
const char* extensionString = reinterpret_cast<const char*>(glGetStringiFunc(GL_EXTENSIONS, i));

extensions.push_back(extensionString);
}
}
}
}
}

// Helper to parse OpenGL version strings
bool parseVersionString(const char* version, const char* prefix, unsigned int &major, unsigned int &minor)
{
Expand Down Expand Up @@ -260,50 +309,7 @@ void GlContext::initResource()
sharedContext->initialize(ContextSettings());

// Load our extensions vector
extensions.clear();

// Check whether a >= 3.0 context is available
int majorVersion = 0;
glGetIntegerv(GL_MAJOR_VERSION, &majorVersion);

if (glGetError() == GL_INVALID_ENUM)
{
// Try to load the < 3.0 way
const char* extensionString = reinterpret_cast<const char*>(glGetString(GL_EXTENSIONS));

do
{
const char* extension = extensionString;

while(*extensionString && (*extensionString != ' '))
extensionString++;

extensions.push_back(std::string(extension, extensionString));
}
while (*extensionString++);
}
else
{
// Try to load the >= 3.0 way
glGetStringiFuncType glGetStringiFunc = NULL;
glGetStringiFunc = reinterpret_cast<glGetStringiFuncType>(getFunction("glGetStringi"));

if (glGetStringiFunc)
{
int numExtensions = 0;
glGetIntegerv(GL_NUM_EXTENSIONS, &numExtensions);

if (numExtensions)
{
for (unsigned int i = 0; i < static_cast<unsigned int>(numExtensions); ++i)
{
const char* extensionString = reinterpret_cast<const char*>(glGetStringiFunc(GL_EXTENSIONS, i));

extensions.push_back(extensionString);
}
}
}
}
loadExtensions();

// Deactivate the shared context so that others can activate it when necessary
sharedContext->setActive(false);
Expand Down Expand Up @@ -417,6 +423,25 @@ GlContext* GlContext::create(const ContextSettings& settings, const WindowImpl*

Lock lock(mutex);

// If resourceCount is 1 we know that we are inside sf::Context or sf::Window
// Only in this situation we allow the user to indirectly re-create the shared context as a core context

// Check if we need to convert our shared context into a core context
if ((resourceCount == 1) &&
(settings.attributeFlags & ContextSettings::Core) &&
!(sharedContext->m_settings.attributeFlags & ContextSettings::Core))
{
// Re-create our shared context as a core context
ContextSettings sharedSettings(0, 0, 0, settings.majorVersion, settings.minorVersion, settings.attributeFlags);

delete sharedContext;
sharedContext = new ContextType(NULL, sharedSettings, 1, 1);
sharedContext->initialize(sharedSettings);

// Reload our extensions vector
loadExtensions();
}

GlContext* context = NULL;

// We don't use acquireTransientContext here since we have
Expand Down Expand Up @@ -446,6 +471,25 @@ GlContext* GlContext::create(const ContextSettings& settings, unsigned int width

Lock lock(mutex);

// If resourceCount is 1 we know that we are inside sf::Context or sf::Window
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DRY code: re-factor this code and the identical one from above into a function. Maybe a template function to accommodate for the width/height vs owner/bpp difference? If the logic is the same (except how context is constructed), I think it makes sense.

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I initially tried to do this, but GlContext::initialize() is private.

// Only in this situation we allow the user to indirectly re-create the shared context as a core context

// Check if we need to convert our shared context into a core context
if ((resourceCount == 1) &&
(settings.attributeFlags & ContextSettings::Core) &&
!(sharedContext->m_settings.attributeFlags & ContextSettings::Core))
{
// Re-create our shared context as a core context
ContextSettings sharedSettings(0, 0, 0, settings.majorVersion, settings.minorVersion, settings.attributeFlags);

delete sharedContext;
sharedContext = new ContextType(NULL, sharedSettings, 1, 1);
sharedContext->initialize(sharedSettings);

// Reload our extensions vector
loadExtensions();
}

GlContext* context = NULL;

// We don't use acquireTransientContext here since we have
Expand Down
39 changes: 18 additions & 21 deletions src/SFML/Window/Win32/WglContext.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -84,20 +84,16 @@ m_deviceContext(NULL),
m_context (NULL),
m_ownsWindow (false)
{
// TODO: Delegate to the other constructor in C++11

// Save the creation settings
m_settings = ContextSettings();

// Make sure that extensions are initialized if this is not the shared context
// The shared context is the context used to initialize the extensions
if (shared && shared->m_deviceContext)
ensureExtensionsInit(shared->m_deviceContext);

// Create the rendering surface (window or pbuffer if supported)
createSurface(shared, 1, 1, VideoMode::getDesktopMode().bitsPerPixel);

// Create the context
if (m_deviceContext)
createContext(shared);
createContext(shared);
}


Expand All @@ -112,17 +108,11 @@ m_ownsWindow (false)
// Save the creation settings
m_settings = settings;

// Make sure that extensions are initialized if this is not the shared context
// The shared context is the context used to initialize the extensions
if (shared && shared->m_deviceContext)
ensureExtensionsInit(shared->m_deviceContext);

// Create the rendering surface from the owner window
createSurface(owner->getSystemHandle(), bitsPerPixel);

// Create the context
if (m_deviceContext)
createContext(shared);
createContext(shared);
}


Expand All @@ -137,17 +127,11 @@ m_ownsWindow (false)
// Save the creation settings
m_settings = settings;

// Make sure that extensions are initialized if this is not the shared context
// The shared context is the context used to initialize the extensions
if (shared && shared->m_deviceContext)
ensureExtensionsInit(shared->m_deviceContext);

// Create the rendering surface (window or pbuffer if supported)
createSurface(shared, width, height, VideoMode::getDesktopMode().bitsPerPixel);

// Create the context
if (m_deviceContext)
createContext(shared);
createContext(shared);
}


Expand Down Expand Up @@ -594,6 +578,10 @@ void WglContext::createSurface(HWND window, unsigned int bitsPerPixel)
////////////////////////////////////////////////////////////
void WglContext::createContext(WglContext* shared)
{
// We can't create an OpenGL context if we don't have a DC
if (!m_deviceContext)
return;

// Get a working copy of the context settings
ContextSettings settings = m_settings;

Expand Down Expand Up @@ -730,6 +718,15 @@ void WglContext::createContext(WglContext* shared)
err() << "Failed to share the OpenGL context: " << getErrorString(GetLastError()).toAnsiString() << std::endl;
}
}

// If we are the shared context, initialize extensions now
// This enables us to re-create the shared context using extensions if we need to
if (!shared && m_context)
{
makeCurrent(true);
ensureExtensionsInit(m_deviceContext);
makeCurrent(false);
}
}

} // namespace priv
Expand Down