[hyun]

hi.

I'm working on Mali-400 with OpenVG library. After drawing on a back surface, eglSwapBuffers switch the back and front buffers.
BTW, I want to draw on partial area of the surface that was on the front buffer before eglSwapBuffers even if it's pre-previous image with setting VG_SCISSORING to VG_TRUE. Scissoring works fine. But, the other part of scissoring rect becomes black, which looks like mali hardware paints VG_CLEAR_COLOR to the other area.
Setting EGL_SWAP_BEHAVIOR to EGL_BUFFER_PRESERVED does not help due to slow speed. Is there any way to draw partial area on the front buffer?

Regards.

[Pete]

Hi hyun,

no - apart from the EGL_BUFFER_PRESERVED option I don't believe there's another way.

You could re-submit all the drawing commands for the new frame, and see how that affects the speed - it may be faster than having EGL preserve the old frame.

If re-submitting is slower (perhaps what you're drawing is complicated) then you could consider drawing it to a VGImage, and just re-draw the VGImage in subsequent frames?

Cheers, Pete

This post has been edited by Pete: 10 September 2010 - 03:24 PM