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• ### Similar Content

• By lxjk
Hi guys,
There are many ways to do light culling in tile-based shading. I've been playing with this idea for a while, and just want to throw it out there.
Because tile frustums are general small compared to light radius, I tried using cone test to reduce false positives introduced by commonly used sphere-frustum test.
On top of that, I use distance to camera rather than depth for near/far test (aka. sliced by spheres).
This method can be naturally extended to clustered light culling as well.
The following image shows the general ideas

Performance-wise I get around 15% improvement over sphere-frustum test. You can also see how a single light performs as the following: from left to right (1) standard rendering of a point light; then tiles passed the test of (2) sphere-frustum test; (3) cone test; (4) spherical-sliced cone test

I put the details in my blog post (https://lxjk.github.io/2018/03/25/Improve-Tile-based-Light-Culling-with-Spherical-sliced-Cone.html), GLSL source code included!

Eric

• Good evening everyone!

I was wondering if there is something equivalent of  GL_NV_blend_equation_advanced for AMD?
Basically I'm trying to find more compatible version of it.

Thank you!

• Hello guys,

How do I know? Why does wavefront not show for me?
I already checked I have non errors yet.

And my download (mega.nz) should it is original but I tried no success...
- Add blend source and png file here I have tried tried,.....

PS: Why is our community not active? I wait very longer. Stop to lie me!
Thanks !

• I wasn't sure if this would be the right place for a topic like this so sorry if it isn't.
I'm currently working on a project for Uni using FreeGLUT to make a simple solar system simulation. I've got to the point where I've implemented all the planets and have used a Scene Graph to link them all together. The issue I'm having with now though is basically the planets and moons orbit correctly at their own orbit speeds.
I'm not really experienced with using matrices for stuff like this so It's likely why I can't figure out how exactly to get it working. This is where I'm applying the transformation matrices, as well as pushing and popping them. This is within the Render function that every planet including the sun and moons will have and run.
if (tag != "Sun") { glRotatef(orbitAngle, orbitRotation.X, orbitRotation.Y, orbitRotation.Z); } glPushMatrix(); glTranslatef(position.X, position.Y, position.Z); glRotatef(rotationAngle, rotation.X, rotation.Y, rotation.Z); glScalef(scale.X, scale.Y, scale.Z); glDrawElements(GL_TRIANGLES, mesh->indiceCount, GL_UNSIGNED_SHORT, mesh->indices); if (tag != "Sun") { glPopMatrix(); } The "If(tag != "Sun")" parts are my attempts are getting the planets to orbit correctly though it likely isn't the way I'm meant to be doing it. So I was wondering if someone would be able to help me? As I really don't have an idea on what I would do to get it working. Using the if statement is truthfully the closest I've got to it working but there are still weird effects like the planets orbiting faster then they should depending on the number of planets actually be updated/rendered.

• Hello everyone,
I have problem with texture

# OpenGL Creating an OpenGL context on Windows with Glew.

This topic is 1395 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

## Recommended Posts

Something weird has happened. I had context creation working just fine. It worked on my desktop and my laptop and I was happily plugging along doing graphics programming. One day I attempt to build my code on my laptop again, suddenly context creation starts to fail. I don't know what has changed.

My original context creation code looks like this

https://gist.github.com/LordTocs/f227528a729986df9643

It's sloppy and has next to no error handling but it at least worked. It still works on my desktop and fails on my laptop.

Specifically wglCreateContextAttribsARB fails.

I started to modify the code in an attempt to figure out what was wrong. I added some "GetLastError()" print outs in hopes I was doing something silly and it would tell me what was wrong. Using "FormatMessage()" to change error code into readable stings.

Instead of a usable error I was greeted with GetLastError() returning 3221692565. Which FormatMessage() had no idea what to do with. A quick cursory internet search lead me to a single result on the opengl forums. Which didn't yield any results

After some reading I was told not to create a forward compatible context. And that I should use wglChoosePixelFormatARB to get the appropriate pixel format. Thinking this was the issue, I tried to use this function, it didn't help.

So now I'm left with this code that doesn't work and I'm very confused.

void DisplayWindowsError()
{
LPVOID lpMsgBuf;
DWORD dw = GetLastError();

FormatMessage(
FORMAT_MESSAGE_ALLOCATE_BUFFER |
FORMAT_MESSAGE_FROM_SYSTEM |
FORMAT_MESSAGE_IGNORE_INSERTS,
NULL,
dw,
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
(LPTSTR)&lpMsgBuf,
0, NULL);

if (lpMsgBuf)
{
std::cout << "Windows Error:" << dw << ": " << (char *)lpMsgBuf << std::endl;
LocalFree(lpMsgBuf);
}
else
{
std::cout << "Windows Error:" << dw << ": unknown" <<  std::endl;
}
}

GraphicsContext::GraphicsContext(ContextTarget &target)
: Target (target)
{
PIXELFORMATDESCRIPTOR pfd =			// pfd Tells Windows How We Want Things To Be
{
sizeof(PIXELFORMATDESCRIPTOR),	// Size Of This Pixel Format Descriptor
1,								// Version Number
PFD_DRAW_TO_WINDOW |			// Format Must Support Window
PFD_SUPPORT_OPENGL |			// Format Must Support OpenGL
PFD_DOUBLEBUFFER,				// Must Support Double Buffering
PFD_TYPE_RGBA,					// Request An RGBA Format
32,								// Select Our Color Depth
0, 0, 0, 0, 0, 0,				// Color Bits Ignored
0,								// No Alpha Buffer
0,								// Shift Bit Ignored
0,								// No Accumulation Buffer
0, 0, 0, 0,						// Accumulation Bits Ignored
24,								// 32Bit Z-Buffer (Depth Buffer)
8,								// No Stencil Buffer
0,								// No Auxiliary Buffer
PFD_MAIN_PLANE,					// Main Drawing Layer
0,								// Reserved
0, 0, 0								// Layer Masks Ignored
};
PixelFormat = 1;
if (!(PixelFormat = ChoosePixelFormat (target.GetHDC (), &pfd)))
{
DisplayWindowsError();
cout << "Failed to choose pixel format." << endl;
}

if (!SetPixelFormat(target.GetHDC(),PixelFormat, &pfd))
{
//DestroyGameWindow (); //Insert Error
DisplayWindowsError();
cout << "Failed to set pixel format." << endl;
}

HGLRC temp;
temp = wglCreateContext(target.GetHDC());
if (!temp)
{
//DestroyGameWindow (); //Insert Error
cout << "Failed to create context" << endl;

}
DisplayWindowsError();
if (!wglMakeCurrent(target.GetHDC (), temp))
{
//DestroyGameWindow ();
cout << "Failed to make current." << endl;
GLErrorCheck();
}
DisplayWindowsError();

GLenum err = glewInit();

if (err != GLEW_OK)
{
char *error = (char *)glewGetErrorString(err);
cout << "GLEW INIT FAIL: " << error << endl;
}

int contextattribs [] =
{
WGL_CONTEXT_MAJOR_VERSION_ARB, 4,
WGL_CONTEXT_MINOR_VERSION_ARB, 2,
#ifdef _DEBUG
WGL_CONTEXT_FLAGS_ARB,  WGL_CONTEXT_DEBUG_BIT_ARB,
#endif
0
};

int pfattribs[] =
{
WGL_DRAW_TO_WINDOW_ARB, GL_TRUE,
WGL_SUPPORT_OPENGL_ARB, GL_TRUE,
WGL_DOUBLE_BUFFER_ARB, GL_TRUE,
WGL_PIXEL_TYPE_ARB, WGL_TYPE_RGBA_ARB,
WGL_COLOR_BITS_ARB, 32,
WGL_DEPTH_BITS_ARB, 24,
WGL_STENCIL_BITS_ARB, 8,
0
};

if (wglewIsSupported ("WGL_ARB_create_context") == 1)
{
unsigned int formatcount;

if (!wglChoosePixelFormatARB(target.GetHDC(), pfattribs, nullptr, 1, (int *)&PixelFormat, &formatcount))
{
std::cout << "Failed to find a matching pixel format" << std::endl;
DisplayWindowsError();
}

if (!SetPixelFormat(target.GetHDC(), PixelFormat, &pfd))
{
DisplayWindowsError();
std::cout << "Failed to set pixelformat" << std::endl;
}

hRC = wglCreateContextAttribsARB(Target.GetHDC(), nullptr, contextattribs);
if (!hRC)
{
DisplayWindowsError();
std::cout << "Failed to create context." << std::endl;
}
wglMakeCurrent(nullptr, nullptr);
DisplayWindowsError();
wglDeleteContext(temp);
DisplayWindowsError();
GLErrorCheck();
MakeCurrent ();

}
else
{
cout << "Failed to create context again..." << endl;
}

#ifdef _DEBUG
glEnable(GL_DEBUG_OUTPUT);
glDebugMessageCallback(dbgcallback, nullptr);
#endif

//GLErrorCheck;
char *version = (char *)glGetString(GL_VERSION);
//GLErrorCheck;
std::cout << "Version: " << version << std::endl << "Shading Version: " << shadeversion << std::endl;

glViewport (0,0,Target.GetWidth (), Target.GetHeight ());
GLErrorCheck ();

SetClearColor (Color(0,0,0,0));
SetClearDepth(1000.0f);
//EnableDepthBuffering ();
//DisableDepthTest ();
NormalBlending ();

glHint(GL_POLYGON_SMOOTH_HINT, GL_NICEST); //Doesn't get Abstracted
GLErrorCheck();

}


If anyone knows what I'm doing wrong I'd love to know.

Thanks.

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int attribs [] =
{
WGL_CONTEXT_MAJOR_VERSION_ARB, 4,
WGL_CONTEXT_MINOR_VERSION_ARB, 2,
#ifdef _DEBUG
WGL_CONTEXT_FLAGS_ARBWGL_CONTEXT_FORWARD_COMPATIBLE_BIT | WGL_CONTEXT_DEBUG_BIT_ARB,
#else
WGL_CONTEXT_FLAGS_ARBWGL_CONTEXT_FORWARD_COMPATIBLE_BIT,
#endif
0
};

I think "WGL_CONTEXT_PROFILE_MASK_ARB, WGL_CONTEXT_CORE_PROFILE_BIT_ARB," is needed for versions greater then 3.2

##### Share on other sites

Hmm I placed it into the "contextattribs []" array in the new code. Still getting the same result. Thanks for the help.

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Is there any reason you can't use something like GLFW?

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I suppose there isn't really a great reason to not use GLFW. Other than I do my own window creation as well. I have a little UI framework that the context creation hooks into as well. I suppose I could fiddle with GLFW to get it all to work in harmony. But I've been using my own context creation for like a year now, it only recently decided to die on my laptop. Is there any reason I can't use my own context creation? It's part "not invented here" syndrome and part curiosity as to what I'm doing wrong. Perhaps I'll look at GLFW's source for hints.

##### Share on other sites

I noticed 3221692565 is 0xC0072095. According to the NVidia create context spec 0x2095 is ERROR_INVALID_VERSION_ARB. So I bumped the version down to 3.3 and it successfully creates a context. Which raises more questions because I should be able to create a 4.2 context. I need a 4.2 context because of shader_storage_buffers and other things.

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Your driver reports OpenGL 4.3, *not* 4.2. Try creating a 4.3 context and see what happens.

OpenGL drivers are notoriously picky about version specifications - on my MacBook the drivers require I specify the exact version supported by the driver, not any previous major/minor version.

Edited by swiftcoder

##### Share on other sites

Interesting thought. Alas, 4.3 fails as well.

Here's where the code's at now.


void DisplayWindowsError()
{
LPVOID lpMsgBuf;
DWORD dw = GetLastError();

FormatMessage(
FORMAT_MESSAGE_ALLOCATE_BUFFER |
FORMAT_MESSAGE_FROM_SYSTEM |
FORMAT_MESSAGE_IGNORE_INSERTS,
NULL,
dw,
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
(LPTSTR)&lpMsgBuf,
0, NULL);

if (lpMsgBuf)
{
std::cout << "Windows Error:" << dw << ": " << (char *)lpMsgBuf << std::endl;
LocalFree(lpMsgBuf);
}
else
{
std::cout << "Windows Error:" << dw << ": unknown " << std::hex << dw <<  std::endl;
}
}

GraphicsContext::GraphicsContext(ContextTarget &target)
: Target (target)
{
PIXELFORMATDESCRIPTOR pfd =			// pfd Tells Windows How We Want Things To Be
{
sizeof(PIXELFORMATDESCRIPTOR),	// Size Of This Pixel Format Descriptor
1,								// Version Number
PFD_DRAW_TO_WINDOW |			// Format Must Support Window
PFD_SUPPORT_OPENGL |			// Format Must Support OpenGL
PFD_DOUBLEBUFFER,				// Must Support Double Buffering
PFD_TYPE_RGBA,					// Request An RGBA Format
32,								// Select Our Color Depth
0, 0, 0, 0, 0, 0,				// Color Bits Ignored
0,								// No Alpha Buffer
0,								// Shift Bit Ignored
0,								// No Accumulation Buffer
0, 0, 0, 0,						// Accumulation Bits Ignored
24,								// 32Bit Z-Buffer (Depth Buffer)
8,								// No Stencil Buffer
0,								// No Auxiliary Buffer
PFD_MAIN_PLANE,					// Main Drawing Layer
0,								// Reserved
0, 0, 0								// Layer Masks Ignored
};
PixelFormat = 1;
if (!(PixelFormat = ChoosePixelFormat (target.GetHDC (), &pfd)))
{
DisplayWindowsError();
cout << "Failed to choose pixel format." << endl;
}

if (!SetPixelFormat(target.GetHDC(),PixelFormat, &pfd))
{
//DestroyGameWindow (); //Insert Error
DisplayWindowsError();
cout << "Failed to set pixel format." << endl;
}

HGLRC temp;
temp = wglCreateContext(target.GetHDC());
if (!temp)
{
//DestroyGameWindow (); //Insert Error
cout << "Failed to create context" << endl;

}
DisplayWindowsError();
if (!wglMakeCurrent(target.GetHDC (), temp))
{
//DestroyGameWindow ();
cout << "Failed to make current." << endl;
GLErrorCheck();
}
DisplayWindowsError();

GLenum err = glewInit();

if (err != GLEW_OK)
{
char *error = (char *)glewGetErrorString(err);
cout << "GLEW INIT FAIL: " << error << endl;
}

int contextattribs [] =
{
WGL_CONTEXT_MAJOR_VERSION_ARB, 4,
WGL_CONTEXT_MINOR_VERSION_ARB, 3,
#ifdef _DEBUG
WGL_CONTEXT_FLAGS_ARB, WGL_CONTEXT_DEBUG_BIT_ARB,
#endif
0
};

int pfattribs[] =
{
WGL_DRAW_TO_WINDOW_ARB, GL_TRUE,
WGL_SUPPORT_OPENGL_ARB, GL_TRUE,
WGL_DOUBLE_BUFFER_ARB, GL_TRUE,
WGL_PIXEL_TYPE_ARB, WGL_TYPE_RGBA_ARB,
WGL_COLOR_BITS_ARB, 32,
WGL_DEPTH_BITS_ARB, 24,
WGL_STENCIL_BITS_ARB, 8,
0
};

if (wglewIsSupported ("WGL_ARB_create_context") == 1)
{
unsigned int formatcount;

if (!wglChoosePixelFormatARB(target.GetHDC(), pfattribs, nullptr, 1, (int *)&PixelFormat, &formatcount))
{
std::cout << "Failed to find a matching pixel format" << std::endl;
DisplayWindowsError();
}

if (!SetPixelFormat(target.GetHDC(), PixelFormat, &pfd))
{
DisplayWindowsError();
std::cout << "Failed to set pixelformat" << std::endl;
}

hRC = wglCreateContextAttribsARB(Target.GetHDC(), nullptr, contextattribs);
if (!hRC)
{
DisplayWindowsError();
std::cout << "Failed to create context." << std::endl;
}
wglMakeCurrent(nullptr, nullptr);
DisplayWindowsError();
wglDeleteContext(temp);
DisplayWindowsError();
GLErrorCheck();
MakeCurrent ();

}
else
{
cout << "Failed to create context again..." << endl;
}

#ifdef _DEBUG
glEnable(GL_DEBUG_OUTPUT);
glDebugMessageCallback(dbgcallback, nullptr);
#endif

//GLErrorCheck;
char *version = (char *)glGetString(GL_VERSION);
//GLErrorCheck;
std::cout << "Version: " << version << std::endl << "Shading Version: " << shadeversion << std::endl;

glViewport (0,0,Target.GetWidth (), Target.GetHeight ());
GLErrorCheck ();

SetClearColor (Color(0,0,0,0));
SetClearDepth(1000.0f);
//EnableDepthBuffering ();
//DisableDepthTest ();
NormalBlending ();

glHint(GL_POLYGON_SMOOTH_HINT, GL_NICEST); //Doesn't get Abstracted
GLErrorCheck();

}


Outputs:
Windows Error:0: The operation completed successfully.
Windows Error:0: The operation completed successfully.
Windows Error:3221692565: unknown c0072095
Failed to create context.

Maybe my drivers need updating or something...

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Setting the major version to 1 and the minor version to 0 in the context attrbute list gives you the latest/highest version supported by the driver at least for compatibility profile context.

After some reading I was told not to create a forward compatible context. And that I should use wglChoosePixelFormatARB to get the appropriate pixel format. Thinking this was the issue, I tried to use this function, it didn't help.

Told by whom. The only thing to be aware of with creating compatiblity context is deprecation, and even if the driver supported a core context, the deprecated functionality is still present in the driver, just not accessible from the core profile context. Feel free to use whatever context that suits you taste. In general its always good to stay away from deprecated functionality in whatever software library you are using, and OpenGL shouldn't be any different in that regards.