Mesa (master): mesa: Set green, blue channels to zero only for formats with these components

[Anuj Phogat]

Module: Mesa
Branch: master
Commit: bbbefec7323d0a338346233ab4ab715bcf4e1b78
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=bbbefec7323d0a338346233ab4ab715bcf4e1b78

Author: Anuj Phogat <anuj.phogat at gmail.com>
Date:   Thu Jun 11 16:44:45 2015 -0700

mesa: Set green, blue channels to zero only for formats with these components

This is an optimization which avoids setting pixel transfer operations
when not required. _mesa_ReadPixels falls back to slower path if
transfer operations are set.

Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
Reviewed-by: Iago Toral Quiroga <itoral at igalia.com>

---

 src/mesa/drivers/common/meta.c |   13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c
index ca10bbe..826f223 100644
--- a/src/mesa/drivers/common/meta.c
+++ b/src/mesa/drivers/common/meta.c
@@ -3159,9 +3159,16 @@ decompress_texture_image(struct gl_context *ctx,
        * returned as red and two-channel texture values are returned as
        * red/alpha.
        */
-      if ((baseTexFormat == GL_LUMINANCE ||
-           baseTexFormat == GL_LUMINANCE_ALPHA ||
-           baseTexFormat == GL_INTENSITY) ||
+      if (((baseTexFormat == GL_LUMINANCE ||
+            baseTexFormat == GL_LUMINANCE_ALPHA ||
+            baseTexFormat == GL_INTENSITY) &&
+           (destBaseFormat == GL_RGBA ||
+            destBaseFormat == GL_RGB ||
+            destBaseFormat == GL_RG ||
+            destBaseFormat == GL_GREEN ||
+            destBaseFormat == GL_BLUE ||
+            destBaseFormat == GL_BGRA ||
+            destBaseFormat == GL_BGR)) ||
           /* If we're reading back an RGB(A) texture (using glGetTexImage) as
 	   * luminance then we need to return L=tex(R).
 	   */