r300g: add support for 3D NPOT textures without mipmapping

The driver actually creates a 3D texture aligned to POT and does all
the magic with texture coordinates in the fragment shader. It first
emulates REPEAT and MIRRORED wrap modes in the fragment shader to get
the coordinates into the range [0, 1]. (already done for 2D NPOT)
Then it scales them to get the coordinates of the NPOT subtexture.

NPOT textures are now less of a lie and we can at least display
something meaningful even for the 3D ones.

Supported wrap modes:
- REPEAT
- MIRRORED_REPEAT
- CLAMP_TO_EDGE (NEAREST filtering only)
- MIRROR_CLAMP_TO_EDGE (NEAREST filtering only)
- The behavior of other CLAMP modes is undefined on borders, but they usually
  give results very close to CLAMP_TO_EDGE with mirroring working perfectly.

This fixes:
- piglit/fbo-3d
- piglit/tex3d-npot

1 files changed, 7 insertions, 0 deletions

diff --git a/src/gallium/drivers/r300/r300_context.h b/src/gallium/drivers/r300/r300_context.h
index 1927370325e..b59bc002610 100644
--- a/src/gallium/drivers/r300/r300_context.h
+++ b/src/gallium/drivers/r300/r300_context.h
@@ -336,6 +336,13 @@ struct r300_texture_desc {
     /* Parent class. */
     struct u_resource b;
 
+    /* Width, height, and depth.
+     * Most of the time, these are equal to pipe_texture::width0, height0,
+     * and depth0. However, NPOT 3D textures must have dimensions aligned
+     * to POT, and this is the only case when these variables differ from
+     * pipe_texture. */
+    unsigned width0, height0, depth0;
+
     /* Buffer tiling.
      * Macrotiling is specified per-level because small mipmaps cannot
      * be macrotiled. */