Hi,
I just wanted to mention that I found a method that solves the
flickering problem in continuous drawing applications:
* right after the frame has been completely drawn, but before doing the
buffer swap, copy the screen image into a texture using
glCopyTexImage2D. This texture should be rgba, have a size coinciding
with the screen resolution, and minification and magnification filtering
set to nearest.
* before starting the drawing of the next frame, render the texture so
it covers the whole screen.
Does this make sense?
ac
Mario Zechner wrote:
oh, i tried that once with OpenGL ES. I didn't use the backbuffer but
drew directly to a texture using an intermediate Bitmap as the drawing
surface and reuploading only those parts of the texture that changed.
You can find a video and an apk of that at
http://apistudios.com/hosted/marzec/badlogic/wordpress/?cat=10. The
problem is that if you update to much of the texture at once you get
100ms interruptions which might be visible to the user.
On 18 Mrz., 14:46, Andres Colubri <andres.colu...@gmail.com> wrote:
What happens in your case is the following (as far as i can tell). In
the first onDrawFrame() call you render some elements to the initially
black back buffer. The front buffer is also black. Now you leave
onDrawFrame() and the back buffer gets presented while the front
buffer becomes your new back buffer. But the new back buffer does not
contain the elements you just rendered! So you render your new
elements to a completely black back buffer this time so the final
image is not a composition of the first onDrawFrame and the second
one. As the buffers are constantly swaped they never have the same
content as half of the elements is in one buffer and the others are in
the other buffer.
Thanks for the explanation, this makes the source of the problem
perfectly clear.
There might be a way to disable double buffering in the GLSurfaceView
if you use that.
That would be nice, I wonder if it is possible to do at all... After a
quick look at the source code of GLSurfaceView, it seems to me that the
double buffering is hard coded into the EglHelper class.
Otherwise you will need to use EGL directly to setup
your OpenGL surface without double buffering.
I'd like to avoid this, since it basically means implementing my own
GLSurfaceView...
On the other hand i wonder why you don't compose your complete scene in a single
onDrawFrame call.
Because the goal is to have an interactive drawing application
controlled by the user input (brushes strokes, etc).
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