• ### Announcements

#### Archived

This topic is now archived and is closed to further replies.

# OpenGL 4 opengl windows in one app

## 16 posts in this topic

hi all can someone tell me why my app only show one of four windows after start? when i start another ogl app it works why not in one app? i need this to create a level editor thx --=[[TheMatrixXXX]]=--
0

##### Share on other sites
You need to create 4 different OGL context (one by window) and bind them before drawing.
0

##### Share on other sites
That can be quite heavy on memory since each context will need copies of the textures.

Often apps will just have one opengl context, one window, and manually handle the different parts inside using the stencil buffer or some other technique.
0

##### Share on other sites
if you use GLUT library, you can use subwindows creation utility
supplied with it.
0

##### Share on other sites
i have the handles in the form class ( i use borland c++ builder 5.0)
but i know thats heavy in memory

can you tell me how to use the glut library in borland c?
i get an error cause it is the M\$ lib format

thx

--=[[TheMatrixXXX]]=--
0

##### Share on other sites
I thought there was a converter or a lib fixer that came with borland to do that. Have a look in the dirs of ur compiler.
0

glViewport?
0

##### Share on other sites
@anonymous poster:
what do you mean with "glViewport?" ?

how can i create different OGL contexts?
why don´t work it with the contexts in the form classes?
they are different i think cause that ar different windows

thx
--=[[TheMatrixXXX]]=--
0

##### Share on other sites
Anon''s right, why not use glViewport?
0

##### Share on other sites
i use glViewport
i have problems with the handles not with the viewport
i have one window of four because the next initialized window overwrites the previous handle i think

or what do you mean with glViewport? can i split a gl window in four parts like in a level editor?

thx
--=[[TheMatrixXXX]]=--
0

##### Share on other sites
You can use the glutCreatSubWindow function

#define space 10 //space betwenn subwindow
Gluint window,first_subwindow,second_subwindow

window = glutCreateWindow("Main Window");
glutReshapeFunc(main_reshape);
glutDisplayFunc(main_display);
glutKeyboardFunc(main_keyboard);

first_subwindow= glutCreateSubWindow(window, space, space, 256, 256);
glutReshapeFunc(world_reshape);
glutDisplayFunc(world_display);
glutKeyboardFunc(main_keyboard);

second_subwindow = glutCreateSubWindow(window, space+256+space, space, 256, 256);
glutReshapeFunc(screen_reshape);
glutDisplayFunc(screen_display);
glutKeyboardFunc(main_keyboard);

I think the glutCreateSubWindow worls like this...
0

##### Share on other sites
glViewport( x, y, width, height ) defines the area in the window where openGL does its rendering. So if you do something like

  glViewport( 0, 0, 100, 100 );doProjection( 100, 100 );renderWindowA();glViewport( 100, 0, 100, 100 );doProjection( 100, 100 );renderWindowB();glViewport( 0, 100, 200, 100 );doProjection( 200, 100 );renderWindowC();

You will have 3 images rendered in your window according to the pattern:

AAABBB
AAABBB
AAABBB
CCCCCC
CCCCCC
CCCCCC
0

##### Share on other sites
@fruny
thx i will try it

--=[[TheMatrixXXX]]=--
0

##### Share on other sites
Be careful to glFlush() and glutSwapBuffer() only once.
0

##### Share on other sites
@fruny:
what do you mean with doProjection?
i have my multiple viewport now but i don´t know how to draw on each one
how can i select them?
i know with the renderWindow but where i have to call these funcs ?
and can i use different views? (gluPerspective and 3xglOrtho)

thx
--=[[TheMatrixXXX]]=--

Edited by - TheMatrixXXX on November 19, 2001 1:31:32 PM
0

##### Share on other sites
If you are doing a projection, it is usually dependent on the width to height ratio of your openGL viewport, no ? So, since I had different sized viewports, I called my doProjection function with the appropriate parameters.

And actually, you don't have several viewports, you have only one. GL will render where you tell it to. That's why I have several renderWindow() functions.

  { glViewport( whole window ); glClear(); glViewport( a corner ); glWhateverProjection( a corner ); Render( a corner ); glViewport( another corner ); glWhateverProjection( another corner ); Render( another corner ); . . . glFlush(); glutSwapBuffers(); // May have to restore the viewport to the whole window though...}

If you want separate input processing for each viewport, you are better off with glut sub-windows, as Major pointed out.

Or you can put 4 calls to glutCreateWindow(), register callbacks for each, save the window handle, and use glutSetWindow() in the right places (e.g. before calls to glutPostRedisplay() ).

(Sorry if I sound confused, I've had 3 hours of sleep over the pas 2 days. )

Edited by - Fruny on November 19, 2001 2:04:18 PM
0

##### Share on other sites
thx i know what you mean

but i want to draw in orthographic views like in a level editor and view the world in a perspective view

i programmed it so far the only problem i have is that the app only show one of four windows and that is a problem of the handles someone told me.

thx
--=[[TheMatrixXXX]]=--
0

• ### Similar Content

• So it's been a while since I took a break from my whole creating a planet in DX11. Last time around I got stuck on fixing a nice LOD.
A week back or so I got help to find this:
https://github.com/sp4cerat/Planet-LOD
In general this is what I'm trying to recreate in DX11, he that made that planet LOD uses OpenGL but that is a minor issue and something I can solve. But I have a question regarding the code
He gets the position using this row
vec4d pos = b.var.vec4d["position"]; Which is then used further down when he sends the variable "center" into the drawing function:
if (pos.len() < 1) pos.norm(); world::draw(vec3d(pos.x, pos.y, pos.z));
Inside the draw function this happens:
draw_recursive(p3[0], p3[1], p3[2], center); Basically the 3 vertices of the triangle and the center of details that he sent as a parameter earlier: vec3d(pos.x, pos.y, pos.z)
Now onto my real question, he does vec3d edge_center[3] = { (p1 + p2) / 2, (p2 + p3) / 2, (p3 + p1) / 2 }; to get the edge center of each edge, nothing weird there.
But this is used later on with:
vec3d d = center + edge_center[i]; edge_test[i] = d.len() > ratio_size; edge_test is then used to evaluate if there should be a triangle drawn or if it should be split up into 3 new triangles instead. Why is it working for him? shouldn't it be like center - edge_center or something like that? Why adding them togheter? I asume here that the center is the center of details for the LOD. the position of the camera if stood on the ground of the planet and not up int he air like it is now.

Full code can be seen here:
https://github.com/sp4cerat/Planet-LOD/blob/master/src.simple/Main.cpp
If anyone would like to take a look and try to help me understand this code I would love this person. I'm running out of ideas on how to solve this in my own head, most likely twisted it one time to many up in my head
Toastmastern

• I googled around but are unable to find source code or details of implementation.
What keywords should I search for this topic?
Things I would like to know:
A. How to ensure that partially covered pixels are rasterized?
Apparently by expanding each triangle by 1 pixel or so, rasterization problem is almost solved.
But it will result in an unindexable triangle list without tons of overlaps. Will it incur a large performance penalty?
How to ensure proper synchronizations in GLSL?
GLSL seems to only allow int32 atomics on image.
C. Is there some simple ways to estimate coverage on-the-fly?
In case I am to draw 2D shapes onto an exisitng target:
1. A multi-pass whatever-buffer seems overkill.
2. Multisampling could cost a lot memory though all I need is better coverage.
Besides, I have to blit twice, if draw target is not multisampled.

• By mapra99
Hello

I am working on a recent project and I have been learning how to code in C# using OpenGL libraries for some graphics. I have achieved some quite interesting things using TAO Framework writing in Console Applications, creating a GLUT Window. But my problem now is that I need to incorporate the Graphics in a Windows Form so I can relate the objects that I render with some .NET Controls.

To deal with this problem, I have seen in some forums that it's better to use OpenTK instead of TAO Framework, so I can use the glControl that OpenTK libraries offer. However, I haven't found complete articles, tutorials or source codes that help using the glControl or that may insert me into de OpenTK functions. Would somebody please share in this forum some links or files where I can find good documentation about this topic? Or may I use another library different of OpenTK?

Thanks!

• Hello, I have been working on SH Irradiance map rendering, and I have been using a GLSL pixel shader to render SH irradiance to 2D irradiance maps for my static objects. I already have it working with 9 3D textures so far for the first 9 SH functions.
In my GLSL shader, I have to send in 9 SH Coefficient 3D Texures that use RGBA8 as a pixel format. RGB being used for the coefficients for red, green, and blue, and the A for checking if the voxel is in use (for the 3D texture solidification shader to prevent bleeding).
My problem is, I want to knock this number of textures down to something like 4 or 5. Getting even lower would be a godsend. This is because I eventually plan on adding more SH Coefficient 3D Textures for other parts of the game map (such as inside rooms, as opposed to the outside), to circumvent irradiance probe bleeding between rooms separated by walls. I don't want to reach the 32 texture limit too soon. Also, I figure that it would be a LOT faster.
Is there a way I could, say, store 2 sets of SH Coefficients for 2 SH functions inside a texture with RGBA16 pixels? If so, how would I extract them from inside GLSL? Let me know if you have any suggestions ^^.
• By KarimIO
EDIT: I thought this was restricted to Attribute-Created GL contexts, but it isn't, so I rewrote the post.
Hey guys, whenever I call SwapBuffers(hDC), I get a crash, and I get a "Too many posts were made to a semaphore." from Windows as I call SwapBuffers. What could be the cause of this?
Update: No crash occurs if I don't draw, just clear and swap.
static 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, // 24Bit Z-Buffer (Depth Buffer) 0, // No Stencil Buffer 0, // No Auxiliary Buffer PFD_MAIN_PLANE, // Main Drawing Layer 0, // Reserved 0, 0, 0 // Layer Masks Ignored }; if (!(hDC = GetDC(windowHandle))) return false; unsigned int PixelFormat; if (!(PixelFormat = ChoosePixelFormat(hDC, &pfd))) return false; if (!SetPixelFormat(hDC, PixelFormat, &pfd)) return false; hRC = wglCreateContext(hDC); if (!hRC) { std::cout << "wglCreateContext Failed!\n"; return false; } if (wglMakeCurrent(hDC, hRC) == NULL) { std::cout << "Make Context Current Second Failed!\n"; return false; } ... // OGL Buffer Initialization glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT); glBindVertexArray(vao); glUseProgram(myprogram); glDrawElements(GL_TRIANGLES, indexCount, GL_UNSIGNED_SHORT, (void *)indexStart); SwapBuffers(GetDC(window_handle));

• 19
• 14
• 23
• 11
• 28