" In HC screenshots are implemented by re-rendering the screen to a texture."
And how do you do that? There is another way to access the texture data beyond using glTexImage2D ? On Sep 13, 5:12 pm, Dianne Hackborn <hack...@android.com> wrote: > As a general rule, the faster the GPU is, the slower and less useful > glReadPixels is. This is certainly not a good way to do high frame rate > video capture. In HC screenshots are implemented by re-rendering the screen > to a texture. > > > > > > > > > > On Tue, Sep 13, 2011 at 7:52 AM, drjunior <drjunior....@gmail.com> wrote: > > What I am trying to do is to capture the framebuffers more than 25 > > times per second. > > Using the Nexus S(with PowerVR SGX 540 GPU) I could capture the > > framebuffers using glReadPixels almost 20 times per second. > > However, with Samsung galaxy S2(MALI 400 GPU) I can only capture the > > framebuffers 8 times per second.... > > > I thought that this could be related with an internal casting that the > > GPU has to do, but now I think that this GPU (MALI 400) doesn't have > > some extension, like PowerVR SGX 540 GPU has, that improves the > > performance of the glreadPixels operation... > > > There is another way to capture the framebuffer without using the > > glReadPixels that is to draw the scenario in a texture and then use > > the glTexImage2D function to copy the data. However, this glTexImage2D > > function is not available on OpenGL ES. > > > On Sep 12, 3:42 pm, dattrax <jimhauxw...@googlemail.com> wrote: > > > ReadPixels is always slow. Not only does it have to flush the GL > > > pipeline, storing information which is not kept on a eglswapbuffers > > > (depth and stencil), but it has to convert from the internal > > > rasterization formats to a RSO format. > > > > If readpixels wasn't required for the CTS, then it would have been > > > removed a long time ago. > > > > What are you trying to do? I suspect there is a more GPU friendly way > > > to achieve the same thing. > > > > Jim > > > > On Sep 6, 10:59 am, drjunior <drjunior....@gmail.com> wrote: > > > > > I am using a samsung galaxy s2 and I am doing a glReadPixels operation > > > > with this parameters: > > > > > glReadPixels(0, 0, sw, sh, GL_RGBA, GL_UNSIGNED_BYTE, ptr); > > > > > But this is taking more than one second to be performed. So, I think > > > > that it's doing some kind of cast from "something" to > > > > GL_UNSIGNED_BYTE. As I don't know how the OpenGL system is initialized > > > > (the framebuffer layout), I also don't know the values that I have to > > > > use in the function in order to avoid the casting. > > > > > Thanks, > > > -- > > unsubscribe: android-porting+unsubscr...@googlegroups.com > > website:http://groups.google.com/group/android-porting > > -- > Dianne Hackborn > Android framework engineer > hack...@android.com > > Note: please don't send private questions to me, as I don't have time to > provide private support, and so won't reply to such e-mails. All such > questions should be posted on public forums, where I and others can see and > answer them. -- unsubscribe: android-porting+unsubscr...@googlegroups.com website: http://groups.google.com/group/android-porting
