st/mesa: ignore gl_texture_object::BaseLevel when allocating gallium textures

Previously, when we created a gallium texture for a corresponding Mesa
texture we'd only allocate space for mipmap levels >= BaseLevel.

This patch undoes that mechanism.  This fixes a render-to-texture bug
when rendering to level 0 when BaseLevel=1.

Also, it makes sense to allocate the whole texture object memory when
BaseLevel > 0 since a common use of GL_TEXTURE_BASE_LEVEL is to
progressively load/render mipmaps.  Eventually, the app almost always
fills in the level=0 mipmap image.

Finally, the texture image code is bit easier to understand now.

1 files changed, 6 insertions, 3 deletions

diff --git a/src/mesa/state_tracker/st_atom_sampler.c b/src/mesa/state_tracker/st_atom_sampler.c
index a8262a5e1a..92fe72d4df 100644
--- a/src/mesa/state_tracker/st_atom_sampler.c
+++ b/src/mesa/state_tracker/st_atom_sampler.c
@@ -194,9 +194,12 @@ update_samplers(struct st_context *st)
             sampler->normalized_coords = 1;
 
          sampler->lod_bias = st->ctx->Texture.Unit[su].LodBias;
-         sampler->min_lod = MAX2(0.0f, texobj->MinLod);
-         sampler->max_lod = MIN2(texobj->MaxLevel - texobj->BaseLevel,
-                                 texobj->MaxLod);
+
+         sampler->min_lod = texobj->BaseLevel + texobj->MinLod;
+         if (sampler->min_lod < texobj->BaseLevel)
+            sampler->min_lod = texobj->BaseLevel;
+
+         sampler->max_lod = MIN2((GLfloat) texobj->MaxLevel, texobj->MaxLod);
          if (sampler->max_lod < sampler->min_lod) {
             /* The GL spec doesn't seem to specify what to do in this case.
              * Swap the values.