[Mesa-dev] [PATCH 4/6] st/mesa: fix guessing the base level size

[Marek Olšák]

It was pretty broken with array textures, where the array size (height or
depth depending on the target) shouldn't be magnified.

The guessing also doesn't fail for 1D and cube textures. (I guess the problem
was only with non-square or non-cube textures, right?)

NOTE: This is a candidate for the stable branches.
---
 src/mesa/state_tracker/st_cb_texture.c |   94 +++++++++++++++-----------------
 1 file changed, 44 insertions(+), 50 deletions(-)

diff --git a/src/mesa/state_tracker/st_cb_texture.c b/src/mesa/state_tracker/st_cb_texture.c
index b2711c3..9619dd2 100644
--- a/src/mesa/state_tracker/st_cb_texture.c
+++ b/src/mesa/state_tracker/st_cb_texture.c
@@ -253,37 +253,6 @@ default_bindings(struct st_context *st, enum pipe_format format)
 }
 
 
-/** Return number of image dimensions (1, 2 or 3) for a texture target. */
-static GLuint
-get_texture_dims(GLenum target)
-{
-   switch (target) {
-   case GL_TEXTURE_1D:
-   case GL_TEXTURE_1D_ARRAY_EXT:
-   case GL_TEXTURE_BUFFER:
-      return 1;
-   case GL_TEXTURE_2D:
-   case GL_TEXTURE_CUBE_MAP_ARB:
-   case GL_TEXTURE_CUBE_MAP_POSITIVE_X_ARB:
-   case GL_TEXTURE_CUBE_MAP_NEGATIVE_X_ARB:
-   case GL_TEXTURE_CUBE_MAP_POSITIVE_Y_ARB:
-   case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y_ARB:
-   case GL_TEXTURE_CUBE_MAP_POSITIVE_Z_ARB:
-   case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z_ARB:
-   case GL_TEXTURE_RECTANGLE_NV:
-   case GL_TEXTURE_2D_ARRAY_EXT:
-   case GL_TEXTURE_EXTERNAL_OES:
-      return 2;
-   case GL_TEXTURE_3D:
-   case GL_TEXTURE_CUBE_MAP_ARRAY:
-      return 3;
-   default:
-      assert(0 && "invalid texture target in get_texture_dims()");
-      return 1;
-   }
-}
-
-
 /**
  * Given the size of a mipmap image, try to compute the size of the level=0
  * mipmap image.
@@ -298,32 +267,57 @@ guess_base_level_size(GLenum target,
                       GLuint width, GLuint height, GLuint depth, GLuint level,
                       GLuint *width0, GLuint *height0, GLuint *depth0)
 { 
-   const GLuint dims = get_texture_dims(target);
-
    assert(width >= 1);
    assert(height >= 1);
    assert(depth >= 1);
 
    if (level > 0) {
-      /* Depending on the image's size, we can't always make a guess here */
-      if ((dims >= 1 && width == 1) ||
-          (dims >= 2 && height == 1) ||
-          (dims >= 3 && depth == 1)) {
-         /* we can't determine the image size at level=0 */
-         return GL_FALSE;
-      }
+      /* Guess the size of the base level.
+       * Depending on the image's size, we can't always make a guess here.
+       */
+      switch (target) {
+      case GL_TEXTURE_1D:
+      case GL_TEXTURE_1D_ARRAY:
+         width <<= level;
+         break;
+
+      case GL_TEXTURE_2D:
+      case GL_TEXTURE_2D_ARRAY:
+         /* We can't make a good guess here, because the base level dimensions
+          * can be non-square.
+          */
+         if (width == 1 || height == 1) {
+            return GL_FALSE;
+         }
+         width <<= level;
+         height <<= level;
+         break;
+
+      case GL_TEXTURE_CUBE_MAP:
+      case GL_TEXTURE_CUBE_MAP_ARRAY:
+         width <<= level;
+         height <<= level;
+         break;
+
+      case GL_TEXTURE_3D:
+         /* We can't make a good guess here, because the base level dimensions
+          * can be non-cube.
+          */
+         if (width == 1 || height == 1 || depth == 1) {
+            return GL_FALSE;
+         }
+         width <<= level;
+         height <<= level;
+         depth <<= level;
+         break;
+
+      case GL_TEXTURE_RECTANGLE:
+         break;
 
-      /* grow the image size until we hit level = 0 */
-      while (level > 0) {
-         if (width > 1)
-            width <<= 1;
-         if (height > 1)
-            height <<= 1;
-         if (depth > 1)
-            depth <<= 1;
-         level--;
+      default:
+         assert(0);
       }
-   }      
+   }
 
    *width0 = width;
    *height0 = height;
-- 
1.7.9.5