meta: Fix blitting a framebuffer with renderbuffer attachment

This patch fixes a case of framebuffer blitting with renderbuffer
as color attachment and GL_LINEAR filter. Meta implementation of
glBlitFrambuffer() converts source color buffer to a texture and
uses it to do the scaled blitting in to destination buffer. Using
the exact source rectangle to create the texture does incorrect
linear filtering along the edges. This patch makes the changes to
extend the texture edges by one pixel in x, y directions. This
ensures correct linear filtering.
It fixes failing piglit fbo-attachments-blit-scaled-linear test.

Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
CC: "9.2" <mesa-stable@lists.freedesktop.org>
CC: "9.1" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Paul Berry <stereotype441@gmail.com>
(cherry picked from commit d944a6144f6ee6a0b24126ce72de280db90038c9)

1 files changed, 15 insertions, 10 deletions

diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c
index 1c36042b873..151da84d7ec 100644
--- a/src/mesa/drivers/common/meta.c
+++ b/src/mesa/drivers/common/meta.c
@@ -1876,19 +1876,24 @@ _mesa_meta_BlitFramebuffer(struct gl_context *ctx,
       const GLenum rb_base_format =
          _mesa_base_tex_format(ctx, colorReadRb->InternalFormat);
 
-      newTex = alloc_texture(tex, srcW, srcH, rb_base_format);
-      setup_copypix_texture(ctx, tex, newTex, srcX, srcY, srcW, srcH,
+      /* Using  the exact source rectangle to create the texture does incorrect
+       * linear filtering along the edges. So, allocate the texture extended along
+       * edges by one pixel in x, y directions.
+       */
+      newTex = alloc_texture(tex, srcW + 2, srcH + 2, rb_base_format);
+      setup_copypix_texture(ctx, tex, newTex,
+                            srcX - 1, srcY - 1, srcW + 2, srcH + 2,
                             rb_base_format, filter);
       /* texcoords (after texture allocation!) */
       {
-         verts[0].s = 0.0F;
-         verts[0].t = 0.0F;
-         verts[1].s = tex->Sright;
-         verts[1].t = 0.0F;
-         verts[2].s = tex->Sright;
-         verts[2].t = tex->Ttop;
-         verts[3].s = 0.0F;
-         verts[3].t = tex->Ttop;
+         verts[0].s = 1.0F;
+         verts[0].t = 1.0F;
+         verts[1].s = tex->Sright - 1.0F;
+         verts[1].t = 1.0F;
+         verts[2].s = tex->Sright - 1.0F;
+         verts[2].t = tex->Ttop - 1.0F;
+         verts[3].s = 1.0F;
+         verts[3].t = tex->Ttop - 1.0F;
 
          /* upload new vertex data */
          _mesa_BufferSubData(GL_ARRAY_BUFFER_ARB, 0, sizeof(verts), verts);