From 8e1c3bd0b4c599bae5b64cd51cec1d74266f30fb Mon Sep 17 00:00:00 2001 From: Brian Date: Fri, 23 Mar 2007 18:01:31 -0600 Subject: Implement alpha buffer copy for SwapBuffers(). Nicolai writes: When the pixmap pixel format has no alpha channel, the x11 driver (software rendering) adds a wrapped alpha channel on request. During SwapBuffers, this alpha channel is not copied from back to front, which means that the front buffer doesn't really contain the contents that the back buffer previously contained. A subsequent glReadPixels from the front buffer will return an incorrect result. The following patch attempts to fix this. --- src/mesa/drivers/x11/xm_api.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'src/mesa/drivers/x11/xm_api.c') diff --git a/src/mesa/drivers/x11/xm_api.c b/src/mesa/drivers/x11/xm_api.c index b513dc8d40..24b19d8eb5 100644 --- a/src/mesa/drivers/x11/xm_api.c +++ b/src/mesa/drivers/x11/xm_api.c @@ -363,7 +363,6 @@ static XMesaBuffer create_xmesa_buffer(XMesaDrawable d, BufferType type, XMesaVisual vis, XMesaColormap cmap) { - GLboolean swAlpha; XMesaBuffer b; ASSERT(type == WINDOW || type == PIXMAP || type == PBUFFER); @@ -421,10 +420,10 @@ create_xmesa_buffer(XMesaDrawable d, BufferType type, /* Visual has alpha, but pixel format doesn't support it. * We'll use an alpha renderbuffer wrapper. */ - swAlpha = GL_TRUE; + b->swAlpha = GL_TRUE; } else { - swAlpha = GL_FALSE; + b->swAlpha = GL_FALSE; } /* @@ -435,9 +434,9 @@ create_xmesa_buffer(XMesaDrawable d, BufferType type, vis->mesa_visual.haveDepthBuffer, vis->mesa_visual.haveStencilBuffer, vis->mesa_visual.haveAccumBuffer, - swAlpha, + b->swAlpha, vis->mesa_visual.numAuxBuffers > 0 ); - + /* insert buffer into linked list */ b->Next = XMesaBufferList; XMesaBufferList = b; @@ -2211,6 +2210,9 @@ void XMesaSwapBuffers( XMesaBuffer b ) ); /*_glthread_UNLOCK_MUTEX(_xmesa_lock);*/ } + + if (b->swAlpha) + _mesa_copy_soft_alpha_renderbuffers(ctx, &b->mesa_buffer); } #if !defined(XFree86Server) XSync( b->xm_visual->display, False ); -- cgit v1.2.3