Well I am a little bit disapointed using opengl and transparent windows on windows 2000 :
the transparent window flicks on top my opengl app and it’s really horrible !
So I searched on this forum and internet and it seems that there is no solution to solve this problem. I tryed several methods to draw my transparent window, so when the transparent window does not flicks there is a gray rectangle on the opengl app when I move the transparent window ;(
So my questions are :
is there really no way to do a clean job ?
why the mouse cursor does not flicks on top the opengl app ? (it’s not a transparent window too ?)
why the mouse cursor does not flicks on top the opengl app ? (it’s not a transparent window too ?)
Because the mouse cursor is a cursor, not a window
The specification states that any part of an OpenGL window that is covered by another window has undefined contents. So there’s no real way to get around this.
…But before that… I am by no means more
than a complete newbie in windows programming,
so don’t even think about flaming me for the
way I do things. If there are alternatives…share with us.
Instead of using OpenGL to update the window contents
you could use it to render to the back buffer or
a pbuffer and then blit the results to the window.
Here is the code:
//it assumes the image was previously rendered
// hWnd is the handle to the window
// hDC is the handle to the device context of the window
RECT rect;
//find out the exact size of the bitmap we need
GetClientRect(hWnd, &rect);
winx = rect.right - rect.left ;
winy = rect.bottom - rect.top ;
//allocate memory to hold the bitmap data
unsigned char* memory = (unsigned char*)malloc(winx * winy * 3);
//read buffer into memory
glReadPixels(0, 0, winx, winy, GL_RGB, GL_UNSIGNED_BYTE, memory);
//setup the bitmap info (size, bitplanes...)
BITMAPINFO bmi;
memset(&bmi, 0, sizeof(bmi));
bmi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
bmi.bmiHeader.biWidth = winx;
bmi.bmiHeader.biHeight = winy; // top-down image
bmi.bmiHeader.biPlanes = 1;
bmi.bmiHeader.biBitCount = 24;
bmi.bmiHeader.biCompression = BI_RGB;
bmi.bmiHeader.biSizeImage = 0;
//replace the current bitmap with the image from the framebuffer
SetDIBitsToDevice(hDC, 0, 0, winx, winy, 0, 0, 0, winy, memory, &bmi, DIB_RGB_COLORS);
free(memory);
I have not tested it thoroughly, so there may be some problems, but it works with no flickering
on my system.
Originally posted by fuxiulian:
[b]Here is my solution to the problem.
…But before that… I am by no means more
than a complete newbie in windows programming,
so don’t even think about flaming me for the
way I do things. If there are alternatives…share with us.
Instead of using OpenGL to update the window contents
you could use it to render to the back buffer or
a pbuffer and then blit the results to the window.
Here is the code:
//it assumes the image was previously rendered
// hWnd is the handle to the window
// hDC is the handle to the device context of the window
Originally posted by Korval:
[b] [quote]why the mouse cursor does not flicks on top the opengl app ? (it’s not a transparent window too ?)
Because the mouse cursor is a cursor, not a window
The specification states that any part of an OpenGL window that is covered by another window has undefined contents. So there’s no real way to get around this.[/b][/QUOTE]_________________________________________
is there a way to have several mouse cursors on the screen (so we’ll have several transparent windows…)
Originally posted by Korval:
[b] [quote]why the mouse cursor does not flicks on top the opengl app ? (it’s not a transparent window too ?)
Because the mouse cursor is a cursor, not a window
The specification states that any part of an OpenGL window that is covered by another window has undefined contents. So there’s no real way to get around this.[/b][/QUOTE]After some research, I found that the mouse cursor is accelerated in hardware
That means that the graphic card have a specific buffer to draw the mouse cursor (3232 or 6464 or sometimes 128128 in true color)
Well after some tests small cursor (6464) do not flick , it’s good but why is this buffer so small ? (It could be used to draw one transparent window !)
What has this got to do with opengl? This is an MS Windows question. Moderators are a fickle bunch - this half arsed topic continues unimpeded, as soda talks to himself about cursors and other basic win32 topics, while other more worthy topics get closed after the first post…I suppose it’s down to whether you use the term opengl enough, which soda obviously has, even though it’s a completely irrelevant term in this context.
Originally posted by knackered: What has this got to do with opengl? This is an MS Windows question. Moderators are a fickle bunch - this half arsed topic continues unimpeded, as soda talks to himself about cursors and other basic win32 topics, while other more worthy topics get closed after the first post…I suppose it’s down to whether you use the term opengl enough, which soda obviously has, even though it’s a completely irrelevant term in this context.
OLA, keep cool
I disagree with you : this is an opengl subject too because there is perhaps a way to solve this problem using opengl code.
Sorry to not be an opengl guru !
Okay I don’t put the topic in the good forum, sorry.
And I don’t talk to myself, I post what I found on this subject, if you are not interested do not read this post !!!
If you search on the old posts you’ll see that other people are intersted to do the same thing as me
