Sign in to follow this  
Seabolt

OpenGL Problem with glClear

Recommended Posts

Seabolt    781
Hey guys,

I'm relatively new to OpenGL rendering so I've decided to start an OpenGL renderer.

This is my Initialization code:

[code]

//////////////////////////////////////////////////////////////////////////
// Platform Specific Initialization (Windows)
#if USING_WINDOWS

// Store the HWND
m_handleWindowHandle = programWindow->GetWindowHandle();

// Do a NULL check if we are in Debug
ASSERT_NULL( m_handleWindowHandle );

// Get the Device Context
m_handleDeviceContext = GetDC( m_handleWindowHandle );

// Null check the DC
ASSERT_NULL( m_handleDeviceContext );

//////////////////////////////////////////////////////////////////////////
// Set the pixel format
m_tPixelFormat.nSize = sizeof( PIXELFORMATDESCRIPTOR ); // Size of the PFD
m_tPixelFormat.nVersion = 1; // Set the version number
m_tPixelFormat.dwFlags = ( PFD_DRAW_TO_WINDOW | // Set the formats
PFD_SUPPORT_OPENGL |
PFD_DOUBLEBUFFER );
m_tPixelFormat.iPixelType = PFD_TYPE_RGBA; // Set the color format
m_tPixelFormat.cColorBits = 32; // Set the color depth
m_tPixelFormat.cDepthBits = 16; // Set the depth buffer depth
m_tPixelFormat.cStencilBits = 0; // Set the stencil buffer depth
m_tPixelFormat.iLayerType = PFD_MAIN_PLANE; // Set the layer for the app

// See if there is a pixel format that will match our requests
int nPixelFormat = 0;
ASSERT_FALSE( nPixelFormat = ChoosePixelFormat( m_handleDeviceContext,
&m_tPixelFormat ) );

ASSERT_FALSE( SetPixelFormat( m_handleDeviceContext,
nPixelFormat,
&m_tPixelFormat ) );
//////////////////////////////////////////////////////////////////////////

//////////////////////////////////////////////////////////////////////////
// So far so good... Now we try to create our RenderContext (HRC)
HGLRC tempContext = wglCreateContext( m_handleDeviceContext );
ASSERT_NULL( tempContext );

// See if the tempContext will work
ASSERT_FALSE( wglMakeCurrent( m_handleDeviceContext, tempContext ) );

GLenum error = glewInit();
if( error != GLEW_OK )
{
fprintf(stderr, "Error: %s\n", glewGetErrorString(error));
}

if( wglewIsSupported( "WGL_ARB_create_context" ) == 1 )
{
// Define our attributes for using OpenGL 3.0 and forward
int attribs[] = {
WGL_CONTEXT_MAJOR_VERSION_ARB, 3,//we want a 3.0 context
WGL_CONTEXT_MINOR_VERSION_ARB, 0,
//and it shall be forward compatible so that we can only use up to date functionality
WGL_CONTEXT_FLAGS_ARB, WGL_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB,
0}; //zero indicates the end of the array

m_handleGLRenderContext = wglCreateContextAttribsARB( m_handleDeviceContext, 0, attribs );
wglMakeCurrent( NULL, NULL );
wglDeleteContext( tempContext );
wglMakeCurrent( m_handleDeviceContext, m_handleGLRenderContext );
}
else
{
m_handleGLRenderContext = tempContext;
}
//////////////////////////////////////////////////////////////////////////
#endif


[/code]




Everything initializes fine and my HDC and HGLRC are fine. My problem is that when I call glClear( COLOR_BUFFER_BIT ) the program locks up and it takes ten to fifteen seconds to close the program when I hit the red x. If I comment out glClear it will run fine. Any ideas?

Share this post


Link to post
Share on other sites
Seabolt    781
Other information:

I'm only calling glClear and the SwapBuffers every frame. It doesn't matter which bits I clear.

My resolution is 1280 by 720.

I set my clear color to be a non-black color.

Share this post


Link to post
Share on other sites
mhagain    13430
You've obviously got a bad context. Could you add some error checking to your 3.0 context creation and see what that gives you back? Also maybe ZeroMemory your m_tPixelFormatbefore doing any creation and make sure that you're not calling ReleaseDC on m_handleDeviceContext while your context exists. CS_OWNDC on your WNDCLASS(EX) shouldn't really be necessary any more, but I prefer to do it [i]anyway [/i]just in case drivers expect it to be there (I've found one or two particularly poor ones that semi-explode without it).

Share this post


Link to post
Share on other sites
Seabolt    781
I am using ZeroMemory on the m_tPixelFormat.

At the time of initialization the HDC = 0x85012263 and the HGLRC = 0x00010001

When I call present the values are the same.

I haven't hit any ReleaseDC calls, accidentally or otherwise.

I'm using CS_OWNDC on my windows for backwards compatibility.

glewInit() returns GLEW_OK

wglMakeCurrent returns fine.

SwapBuffers returns fine.

Share this post


Link to post
Share on other sites
Seabolt    781
As of now, I can debug and step through all the functions fine with no errors being thrown. In fact, I can debug with no slow down either. But if I just let the program run the screen A.) doesn't clear to the color I specified and B.) doesn't respond to window messages very fast (like ten to fourty five seconds slow). This only happens if I call glClear. Someone must have ran into this before.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Similar Content

    • By Arulbabu Donbosco
      There are studios selling applications which is just copying any 3Dgraphic content and regenerating into another new window. especially for CAVE Virtual reality experience. so that the user opens REvite or CAD or any other 3D applications and opens a model. then when the user selects the rendered window the VR application copies the 3D model information from the OpenGL window. 
      I got the clue that the VR application replaces the windows opengl32.dll file. how this is possible ... how can we copy the 3d content from the current OpenGL window.
      anyone, please help me .. how to go further... to create an application like VR CAVE. 
       
      Thanks
    • By cebugdev
      hi all,

      i am trying to build an OpenGL 2D GUI system, (yeah yeah, i know i should not be re inventing the wheel, but this is for educational and some other purpose only),
      i have built GUI system before using 2D systems such as that of HTML/JS canvas, but in 2D system, i can directly match a mouse coordinates to the actual graphic coordinates with additional computation for screen size/ratio/scale ofcourse.
      now i want to port it to OpenGL, i know that to render a 2D object in OpenGL we specify coordiantes in Clip space or use the orthographic projection, now heres what i need help about.
      1. what is the right way of rendering the GUI? is it thru drawing in clip space or switching to ortho projection?
      2. from screen coordinates (top left is 0,0 nd bottom right is width height), how can i map the mouse coordinates to OpenGL 2D so that mouse events such as button click works? In consideration ofcourse to the current screen/size dimension.
      3. when let say if the screen size/dimension is different, how to handle this? in my previous javascript 2D engine using canvas, i just have my working coordinates and then just perform the bitblk or copying my working canvas to screen canvas and scale the mouse coordinates from there, in OpenGL how to work on a multiple screen sizes (more like an OpenGL ES question).
      lastly, if you guys know any books, resources, links or tutorials that handle or discuss this, i found one with marekknows opengl game engine website but its not free,
      Just let me know. Did not have any luck finding resource in google for writing our own OpenGL GUI framework.
      IF there are no any available online, just let me know, what things do i need to look into for OpenGL and i will study them one by one to make it work.
      thank you, and looking forward to positive replies.
    • By fllwr0491
      I have a few beginner questions about tesselation that I really have no clue.
      The opengl wiki doesn't seem to talk anything about the details.
       
      What is the relationship between TCS layout out and TES layout in?
      How does the tesselator know how control points are organized?
          e.g. If TES input requests triangles, but TCS can output N vertices.
             What happens in this case?
      In this article,
      http://www.informit.com/articles/article.aspx?p=2120983
      the isoline example TCS out=4, but TES in=isoline.
      And gl_TessCoord is only a single one.
      So which ones are the control points?
      How are tesselator building primitives?
    • By Orella
      I've been developing a 2D Engine using SFML + ImGui.
      Here you can see an image
      The editor is rendered using ImGui and the scene window is a sf::RenderTexture where I draw the GameObjects and then is converted to ImGui::Image to render it in the editor.
      Now I need to create a 3D Engine during this year in my Bachelor Degree but using SDL2 + ImGui and I want to recreate what I did with the 2D Engine. 
      I've managed to render the editor like I did in the 2D Engine using this example that comes with ImGui. 
      3D Editor preview
      But I don't know how to create an equivalent of sf::RenderTexture in SDL2, so I can draw the 3D scene there and convert it to ImGui::Image to show it in the editor.
      If you can provide code will be better. And if you want me to provide any specific code tell me.
      Thanks!
    • By Picpenguin
      Hi
      I'm new to learning OpenGL and still learning C. I'm using SDL2, glew, OpenGL 3.3, linmath and stb_image.
      I started following through learnopengl.com and got through it until I had to load models. The problem is, it uses Assimp for loading models. Assimp is C++ and uses things I don't want in my program (boost for example) and C support doesn't seem that good.
      Things like glVertexAttribPointer and shaders are still confusing to me, but I have to start somewhere right?
      I can't seem to find any good loading/rendering tutorials or source code that is simple to use and easy to understand.
      I have tried this for over a week by myself, searching for solutions but so far no luck. With tinyobjloader-c and project that uses it, FantasyGolfSimulator, I was able to actually load the model with plain color (always the same color no matter what I do) on screen and move it around, but cannot figure out how to use textures or use its multiple textures with it.
      I don't ask much: I just want to load models with textures in them, maybe have lights affect them (directional spotlight etc). Also, some models have multiple parts and multiple textures in them, how can I handle those?
      Are there solutions anywhere?
      Thank you for your time. Sorry if this is a bit confusing, English isn't my native language
  • Popular Now