4 files changed, 43 insertions, 5 deletions

diff --git a/src/mesa/drivers/x11/xm_api.c b/src/mesa/drivers/x11/xm_api.c
index b513dc8d40a..24b19d8eb5a 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 );
diff --git a/src/mesa/drivers/x11/xmesaP.h b/src/mesa/drivers/x11/xmesaP.h
index 5516031ffe7..85cb6b66363 100644
--- a/src/mesa/drivers/x11/xmesaP.h
+++ b/src/mesa/drivers/x11/xmesaP.h
@@ -224,6 +224,7 @@ struct xmesa_buffer {
    GLint db_mode;		/* 0 = single buffered */
 				/* BACK_PIXMAP = use Pixmap for back buffer */
 				/* BACK_XIMAGE = use XImage for back buffer */
+   GLboolean swAlpha;
 
    GLuint shm;			/* X Shared Memory extension status:	*/
 				/*    0 = not available			*/
diff --git a/src/mesa/main/renderbuffer.c b/src/mesa/main/renderbuffer.c
index e387c42c345..ded0063c739 100644
--- a/src/mesa/main/renderbuffer.c
+++ b/src/mesa/main/renderbuffer.c
@@ -1435,6 +1435,17 @@ put_mono_values_alpha8(GLcontext *ctx, struct gl_renderbuffer *arb,
 }
 
 
+static void
+copy_buffer_alpha8(struct gl_renderbuffer* dst, struct gl_renderbuffer* src)
+{
+   ASSERT(dst->_ActualFormat == GL_ALPHA8);
+   ASSERT(src->_ActualFormat == GL_ALPHA8);
+   ASSERT(dst->Width == src->Width);
+   ASSERT(dst->Height == src->Height);
+
+   _mesa_memcpy(dst->Data, src->Data, dst->Width * dst->Height * sizeof(GLubyte));
+}
+
 
 /**********************************************************************/
 /**********************************************************************/
@@ -1766,6 +1777,27 @@ _mesa_add_alpha_renderbuffers(GLcontext *ctx, struct gl_framebuffer *fb,
 
 
 /**
+ * For framebuffers that use a software alpha channel wrapper
+ * created by _mesa_add_alpha_renderbuffer or _mesa_add_soft_renderbuffers,
+ * copy the back buffer alpha channel into the front buffer alpha channel.
+ */
+void
+_mesa_copy_soft_alpha_renderbuffers(GLcontext *ctx, struct gl_framebuffer *fb)
+{
+   if (fb->Attachment[BUFFER_FRONT_LEFT].Renderbuffer &&
+       fb->Attachment[BUFFER_BACK_LEFT].Renderbuffer)
+      copy_buffer_alpha8(fb->Attachment[BUFFER_FRONT_LEFT].Renderbuffer,
+                         fb->Attachment[BUFFER_BACK_LEFT].Renderbuffer);
+
+
+   if (fb->Attachment[BUFFER_FRONT_RIGHT].Renderbuffer &&
+       fb->Attachment[BUFFER_BACK_RIGHT].Renderbuffer)
+      copy_buffer_alpha8(fb->Attachment[BUFFER_FRONT_RIGHT].Renderbuffer,
+                         fb->Attachment[BUFFER_BACK_RIGHT].Renderbuffer);
+}
+
+
+/**
  * Add a software-based depth renderbuffer to the given framebuffer.
  * This is a helper routine for device drivers when creating a
  * window system framebuffer (not a user-created render/framebuffer).
diff --git a/src/mesa/main/renderbuffer.h b/src/mesa/main/renderbuffer.h
index e1a0a559792..e5f1147b4a6 100644
--- a/src/mesa/main/renderbuffer.h
+++ b/src/mesa/main/renderbuffer.h
@@ -64,6 +64,9 @@ _mesa_add_alpha_renderbuffers(GLcontext *ctx, struct gl_framebuffer *fb,
                               GLboolean frontLeft, GLboolean backLeft,
                               GLboolean frontRight, GLboolean backRight);
 
+extern void
+_mesa_copy_soft_alpha_renderbuffers(GLcontext *ctx, struct gl_framebuffer *fb);
+
 extern GLboolean
 _mesa_add_depth_renderbuffer(GLcontext *ctx, struct gl_framebuffer *fb,
                              GLuint depthBits);