[Mesa-dev] [PATCH 1/4] meta: fix GetTexImage() for compressed luminance, l/a, intensity formats

[Brian Paul]

From: Brian Paul <brianp at vmware.com>

The GL spec says that luminance values are returned as (l, 0, 0, 1),
L/A values as (l, 0, 0, a) and intensity values as (i, 0, 0, 1).
Use the pixel transfer scale controls to implement that.
This fixes a few failures in the new piglit getteximage-formats
test when getting a compressed L or L/A image.
---
 src/mesa/drivers/common/meta.c |   24 ++++++++++++++++++++++--
 src/mesa/main/pixel.c          |    2 +-
 src/mesa/main/pixel.h          |    9 +++++++++
 3 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c
index b6e80d7..b47eb2c 100644
--- a/src/mesa/drivers/common/meta.c
+++ b/src/mesa/drivers/common/meta.c
@@ -49,6 +49,7 @@
 #include "main/macros.h"
 #include "main/matrix.h"
 #include "main/mipmap.h"
+#include "main/pixel.h"
 #include "main/pbo.h"
 #include "main/polygon.h"
 #include "main/readpix.h"
@@ -3235,8 +3236,27 @@ decompress_texture_image(struct gl_context *ctx,
    }
 
    /* read pixels from renderbuffer */
-   ctx->Pack.RowLength = destRowLength;
-   _mesa_ReadPixels(0, 0, width, height, destFormat, destType, dest);
+   {
+      GLenum baseTexFormat = _mesa_get_format_base_format(texImage->TexFormat);
+
+      /* The pixel transfer state will be set to default values at this point
+       * (see MESA_META_PIXEL_TRANSFER) so pixel transfer ops are effectively
+       * turned off (as required by glGetTexImage) but we need to handle some
+       * special cases.  In particular, single-channel texture values are
+       * returned as red and two-channel texture values are returned as
+       * red/alpha.
+       */
+      if (baseTexFormat == GL_LUMINANCE ||
+          baseTexFormat == GL_LUMINANCE_ALPHA ||
+          baseTexFormat == GL_INTENSITY) {
+         /* Green and blue must be zero */
+         _mesa_PixelTransferf(GL_GREEN_SCALE, 0.0f);
+         _mesa_PixelTransferf(GL_BLUE_SCALE, 0.0f);
+      }
+
+      ctx->Pack.RowLength = destRowLength;
+      _mesa_ReadPixels(0, 0, width, height, destFormat, destType, dest);
+   }
 
    /* disable texture unit */
    _mesa_set_enable(ctx, target, GL_FALSE);
diff --git a/src/mesa/main/pixel.c b/src/mesa/main/pixel.c
index c87f5e0..e73c5a4 100644
--- a/src/mesa/main/pixel.c
+++ b/src/mesa/main/pixel.c
@@ -506,7 +506,7 @@ _mesa_GetPixelMapusv( GLenum map, GLushort *values )
  * Implements glPixelTransfer[fi] whether called immediately or from a
  * display list.
  */
-static void GLAPIENTRY
+void GLAPIENTRY
 _mesa_PixelTransferf( GLenum pname, GLfloat param )
 {
    GET_CURRENT_CONTEXT(ctx);
diff --git a/src/mesa/main/pixel.h b/src/mesa/main/pixel.h
index 6f04eb6..558b106 100644
--- a/src/mesa/main/pixel.h
+++ b/src/mesa/main/pixel.h
@@ -43,6 +43,9 @@ struct gl_context;
 
 #if FEATURE_pixel_transfer
 
+extern void GLAPIENTRY
+_mesa_PixelTransferf(GLenum pname, GLfloat param);
+
 extern void 
 _mesa_update_pixel( struct gl_context *ctx, GLuint newstate );
 
@@ -51,6 +54,12 @@ _mesa_init_pixel_dispatch( struct _glapi_table * disp );
 
 #else /* FEATURE_pixel_transfer */
 
+static inline void GLAPIENTRY
+_mesa_PixelTransferf(GLenum pname, GLfloat param)
+{
+}
+
+
 static INLINE void
 _mesa_update_pixel(struct gl_context *ctx, GLuint newstate)
 {
-- 
1.7.3.4