mesa: call ctx->Driver.ChooseTextureFormat() only when necessary.

When defining mipmap level 'L' and level L-1 exists and the new level's
internalFormat matches level L-1's internalFormat, then use the same hw
format.  Otherwise, do the regular ctx->Driver.ChooseTextureFormat() call.

This avoids a problem where we end up choosing different hw formats for
different mipmap levels depending on how the levels are defined (glTexImage
vs. glCopyTexImage vs. glGenerateMipmap, etc).

The root problem is the ChooseTextureFormat() implementation in some
drivers uses the user's glTexImage format/type parameters in the choosing
heuristic.  Later mipmap levels might be generated with different calls
(ex: glCopyTexImage()) so we don't always have format/type info and the
driver may choose a different format.

For more background info see the July 2010 mesa-dev thread "Bug in
_mesa_meta_GenerateMipmap"

3 files changed, 84 insertions, 51 deletions

diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c
index c548e104203..dc6e7120c63 100644
--- a/src/mesa/drivers/common/meta.c
+++ b/src/mesa/drivers/common/meta.c
@@ -2570,12 +2570,6 @@ copy_tex_image(GLcontext *ctx, GLuint dims, GLenum target, GLint level,
       return;
    }
 
-   if (texImage->TexFormat == MESA_FORMAT_NONE)
-      texImage->TexFormat = ctx->Driver.ChooseTextureFormat(ctx,
-                                                            internalFormat,
-                                                            format,
-                                                            type);
-
    _mesa_unlock_texture(ctx, texObj); /* need to unlock first */
 
    /*
@@ -2604,6 +2598,9 @@ copy_tex_image(GLcontext *ctx, GLuint dims, GLenum target, GLint level,
                               postConvWidth, postConvHeight, 1,
                               border, internalFormat);
 
+   _mesa_choose_texture_format(ctx, texObj, texImage, target, level,
+                               internalFormat, GL_NONE, GL_NONE);
+
    /*
     * Store texture data (with pixel transfer ops)
     */
diff --git a/src/mesa/main/teximage.c b/src/mesa/main/teximage.c
index 29b721d0bee..9b7a0215619 100644
--- a/src/mesa/main/teximage.c
+++ b/src/mesa/main/teximage.c
@@ -2183,6 +2183,45 @@ override_internal_format(GLenum internalFormat, GLint width, GLint height)
 }
 
 
+/**
+ * Choose the actual hardware format for a texture image.
+ * Try to use the same format as the previous image level when possible.
+ * Otherwise, ask the driver for the best format.
+ * It's important to try to choose a consistant format for all levels
+ * for efficient texture memory layout/allocation.  In particular, this
+ * comes up during automatic mipmap generation.
+ */
+void
+_mesa_choose_texture_format(GLcontext *ctx,
+                            struct gl_texture_object *texObj,
+                            struct gl_texture_image *texImage,
+                            GLenum target, GLint level,
+                            GLenum internalFormat, GLenum format, GLenum type)
+{
+   /* see if we've already chosen a format for the previous level */
+   if (level > 0) {
+      struct gl_texture_image *prevImage =
+	 _mesa_select_tex_image(ctx, texObj, target, level - 1);
+      /* See if the prev level is defined and has an internal format which
+       * matches the new internal format.
+       */
+      if (prevImage &&
+          prevImage->Width > 0 &&
+          prevImage->InternalFormat == internalFormat) {
+         /* use the same format */
+         texImage->TexFormat = prevImage->TexFormat;
+         return;
+      }
+   }
+
+   /* choose format from scratch */
+   texImage->TexFormat = ctx->Driver.ChooseTextureFormat(ctx, internalFormat,
+                                                         format, type);
+   ASSERT(texImage->TexFormat != MESA_FORMAT_NONE);
+}
+
+
+
 /*
  * Called from the API.  Note that width includes the border.
  */
@@ -2243,11 +2282,8 @@ _mesa_TexImage1D( GLenum target, GLint level, GLint internalFormat,
                                        postConvWidth, 1, 1,
                                        border, internalFormat);
 
-            /* Choose actual texture format */
-            texImage->TexFormat =
-               ctx->Driver.ChooseTextureFormat(ctx, internalFormat,
-                                               format, type);
-            ASSERT(texImage->TexFormat != MESA_FORMAT_NONE);
+            _mesa_choose_texture_format(ctx, texObj, texImage, target, level,
+                                        internalFormat, format, type);
 
             /* Give the texture to the driver.  <pixels> may be null. */
             ASSERT(ctx->Driver.TexImage1D);
@@ -2282,12 +2318,14 @@ _mesa_TexImage1D( GLenum target, GLint level, GLint internalFormat,
       }
       else {
          /* no error, set the tex image parameters */
+         struct gl_texture_object *texObj =
+            _mesa_get_current_tex_object(ctx, target);
          ASSERT(texImage);
          _mesa_init_teximage_fields(ctx, target, texImage,
                                     postConvWidth, 1, 1,
                                     border, internalFormat);
-         texImage->TexFormat =
-            ctx->Driver.ChooseTextureFormat(ctx, internalFormat, format, type);
+         _mesa_choose_texture_format(ctx, texObj, texImage, target, level,
+                                     internalFormat, format, type);
       }
    }
    else {
@@ -2363,11 +2401,8 @@ _mesa_TexImage2D( GLenum target, GLint level, GLint internalFormat,
                                        postConvWidth, postConvHeight, 1,
                                        border, internalFormat);
 
-            /* Choose actual texture format */
-            texImage->TexFormat =
-               ctx->Driver.ChooseTextureFormat(ctx, internalFormat,
-                                               format, type);
-            ASSERT(texImage->TexFormat != MESA_FORMAT_NONE);
+            _mesa_choose_texture_format(ctx, texObj, texImage, target, level,
+                                        internalFormat, format, type);
 
             /* Give the texture to the driver.  <pixels> may be null. */
             ASSERT(ctx->Driver.TexImage2D);
@@ -2409,11 +2444,13 @@ _mesa_TexImage2D( GLenum target, GLint level, GLint internalFormat,
       }
       else {
          /* no error, set the tex image parameters */
+         struct gl_texture_object *texObj =
+            _mesa_get_current_tex_object(ctx, target);
          _mesa_init_teximage_fields(ctx, target, texImage,
                                     postConvWidth, postConvHeight, 1,
                                     border, internalFormat);
-         texImage->TexFormat =
-            ctx->Driver.ChooseTextureFormat(ctx, internalFormat, format, type);
+         _mesa_choose_texture_format(ctx, texObj, texImage, target, level,
+                                     internalFormat, format, type);
       }
    }
    else {
@@ -2479,11 +2516,8 @@ _mesa_TexImage3D( GLenum target, GLint level, GLint internalFormat,
                                        width, height, depth,
                                        border, internalFormat);
 
-            /* Choose actual texture format */
-            texImage->TexFormat =
-               ctx->Driver.ChooseTextureFormat(ctx, internalFormat,
-                                               format, type);
-            ASSERT(texImage->TexFormat != MESA_FORMAT_NONE);
+            _mesa_choose_texture_format(ctx, texObj, texImage, target, level,
+                                        internalFormat, format, type);
 
             /* Give the texture to the driver.  <pixels> may be null. */
             ASSERT(ctx->Driver.TexImage3D);
@@ -2520,10 +2554,12 @@ _mesa_TexImage3D( GLenum target, GLint level, GLint internalFormat,
       }
       else {
          /* no error, set the tex image parameters */
+         struct gl_texture_object *texObj =
+            _mesa_get_current_tex_object(ctx, target);
          _mesa_init_teximage_fields(ctx, target, texImage, width, height,
                                     depth, border, internalFormat);
-         texImage->TexFormat =
-            ctx->Driver.ChooseTextureFormat(ctx, internalFormat, format, type);
+         _mesa_choose_texture_format(ctx, texObj, texImage, target, level,
+                                     internalFormat, format, type);
       }
    }
    else {
@@ -2836,11 +2872,8 @@ _mesa_CopyTexImage1D( GLenum target, GLint level,
          _mesa_init_teximage_fields(ctx, target, texImage, postConvWidth, 1, 1,
                                     border, internalFormat);
 
-         /* Choose actual texture format */
-         texImage->TexFormat =
-            ctx->Driver.ChooseTextureFormat(ctx, internalFormat,
-                                            GL_NONE, GL_NONE);
-         ASSERT(texImage->TexFormat != MESA_FORMAT_NONE);
+         _mesa_choose_texture_format(ctx, texObj, texImage, target, level,
+                                     internalFormat, GL_NONE, GL_NONE);
 
          ASSERT(ctx->Driver.CopyTexImage1D);
          ctx->Driver.CopyTexImage1D(ctx, target, level, internalFormat,
@@ -2917,11 +2950,8 @@ _mesa_CopyTexImage2D( GLenum target, GLint level, GLenum internalFormat,
                                     postConvWidth, postConvHeight, 1,
                                     border, internalFormat);
 
-         /* Choose actual texture format */
-         texImage->TexFormat =
-            ctx->Driver.ChooseTextureFormat(ctx, internalFormat,
-                                            GL_NONE, GL_NONE);
-         ASSERT(texImage->TexFormat != MESA_FORMAT_NONE);
+         _mesa_choose_texture_format(ctx, texObj, texImage, target, level,
+                                     internalFormat, GL_NONE, GL_NONE);
 
          ASSERT(ctx->Driver.CopyTexImage2D);
          ctx->Driver.CopyTexImage2D(ctx, target, level, internalFormat,
@@ -3446,11 +3476,8 @@ _mesa_CompressedTexImage1DARB(GLenum target, GLint level,
             _mesa_init_teximage_fields(ctx, target, texImage, width, 1, 1,
                                        border, internalFormat);
 
-            /* Choose actual texture format */
-            texImage->TexFormat =
-               ctx->Driver.ChooseTextureFormat(ctx, internalFormat,
-                                               GL_NONE, GL_NONE);
-            ASSERT(texImage->TexFormat != MESA_FORMAT_NONE);
+            _mesa_choose_texture_format(ctx, texObj, texImage, target, level,
+                                        internalFormat, GL_NONE, GL_NONE);
 
             ASSERT(ctx->Driver.CompressedTexImage1D);
             ctx->Driver.CompressedTexImage1D(ctx, target, level,
@@ -3498,6 +3525,8 @@ _mesa_CompressedTexImage1DARB(GLenum target, GLint level,
 	    texImage = _mesa_select_tex_image(ctx, texObj, target, level);
 	    _mesa_init_teximage_fields(ctx, target, texImage, width, 1, 1,
 				       border, internalFormat);
+            _mesa_choose_texture_format(ctx, texObj, texImage, target, level,
+                                        internalFormat, GL_NONE, GL_NONE);
 	 }
 	 _mesa_unlock_texture(ctx, texObj);
       }
@@ -3573,11 +3602,8 @@ _mesa_CompressedTexImage2DARB(GLenum target, GLint level,
             _mesa_init_teximage_fields(ctx, target, texImage, width, height, 1,
                                        border, internalFormat);
 
-            /* Choose actual texture format */
-            texImage->TexFormat =
-               ctx->Driver.ChooseTextureFormat(ctx, internalFormat,
-                                               GL_NONE, GL_NONE);
-            ASSERT(texImage->TexFormat != MESA_FORMAT_NONE);
+            _mesa_choose_texture_format(ctx, texObj, texImage, target, level,
+                                        internalFormat, GL_NONE, GL_NONE);
 
             ASSERT(ctx->Driver.CompressedTexImage2D);
             ctx->Driver.CompressedTexImage2D(ctx, target, level,
@@ -3627,6 +3653,8 @@ _mesa_CompressedTexImage2DARB(GLenum target, GLint level,
 	    texImage = _mesa_select_tex_image(ctx, texObj, target, level);
 	    _mesa_init_teximage_fields(ctx, target, texImage, width, height, 1,
 				       border, internalFormat);
+            _mesa_choose_texture_format(ctx, texObj, texImage, target, level,
+                                        internalFormat, GL_NONE, GL_NONE);
 	 }
 	 _mesa_unlock_texture(ctx, texObj);
       }
@@ -3683,10 +3711,8 @@ _mesa_CompressedTexImage3DARB(GLenum target, GLint level,
                                        border, internalFormat);
 
             /* Choose actual texture format */
-            texImage->TexFormat =
-               ctx->Driver.ChooseTextureFormat(ctx, internalFormat,
-                                               GL_NONE, GL_NONE);
-            ASSERT(texImage->TexFormat != MESA_FORMAT_NONE);
+            _mesa_choose_texture_format(ctx, texObj, texImage, target, level,
+                                        internalFormat, GL_NONE, GL_NONE);
 
             ASSERT(ctx->Driver.CompressedTexImage3D);
             ctx->Driver.CompressedTexImage3D(ctx, target, level,
@@ -3735,6 +3761,8 @@ _mesa_CompressedTexImage3DARB(GLenum target, GLint level,
 	    texImage = _mesa_select_tex_image(ctx, texObj, target, level);
 	    _mesa_init_teximage_fields(ctx, target, texImage, width, height,
 				       depth, border, internalFormat);
+            _mesa_choose_texture_format(ctx, texObj, texImage, target, level,
+                                        internalFormat, GL_NONE, GL_NONE);
 	 }
 	 _mesa_unlock_texture(ctx, texObj);
       }
diff --git a/src/mesa/main/teximage.h b/src/mesa/main/teximage.h
index d82cc985211..0dcacab3cd0 100644
--- a/src/mesa/main/teximage.h
+++ b/src/mesa/main/teximage.h
@@ -73,6 +73,14 @@ _mesa_init_teximage_fields(GLcontext *ctx, GLenum target,
 
 
 extern void
+_mesa_choose_texture_format(GLcontext *ctx,
+                            struct gl_texture_object *texObj,
+                            struct gl_texture_image *texImage,
+                            GLenum target, GLint level,
+                            GLenum internalFormat, GLenum format, GLenum type);
+
+
+extern void
 _mesa_clear_texture_image(GLcontext *ctx, struct gl_texture_image *texImage);