Mesa (9.2): meta: Fix blitting a framebuffer with renderbuffer attachment

[Ian Romanick]

Module: Mesa
Branch: 9.2
Commit: d72f7720a6de538da21d883688d34bbaf656b542
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=d72f7720a6de538da21d883688d34bbaf656b542

Author: Anuj Phogat <anuj.phogat at gmail.com>
Date:   Mon Aug  5 14:27:47 2013 -0700

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 at gmail.com>
CC: "9.2" <mesa-stable at lists.freedesktop.org>
CC: "9.1" <mesa-stable at lists.freedesktop.org>
Reviewed-by: Paul Berry <stereotype441 at gmail.com>
(cherry picked from commit d944a6144f6ee6a0b24126ce72de280db90038c9)

---

 src/mesa/drivers/common/meta.c |   25 +++++++++++++++----------
 1 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c
index 286f32e..cfcd0e2 100644
--- a/src/mesa/drivers/common/meta.c
+++ b/src/mesa/drivers/common/meta.c
@@ -1884,19 +1884,24 @@ _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);