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, 12 insertions, 4 deletions

diff --git a/src/gallium/drivers/r300/r300_emit.c b/src/gallium/drivers/r300/r300_emit.c
index db783ff0ad..3a1085d2dc 100644
--- a/src/gallium/drivers/r300/r300_emit.c
+++ b/src/gallium/drivers/r300/r300_emit.c
@@ -89,7 +89,7 @@ static const float * get_rc_constant_state(
 {
     struct r300_textures_state* texstate = r300->textures_state.state;
     static float vec[4] = { 0.0, 0.0, 0.0, 1.0 };
-    struct pipe_resource *tex;
+    struct r300_texture *tex;
 
     assert(constant->Type == RC_CONSTANT_STATE);
 
@@ -97,9 +97,17 @@ static const float * get_rc_constant_state(
         /* Factor for converting rectangle coords to
          * normalized coords. Should only show up on non-r500. */
         case RC_STATE_R300_TEXRECT_FACTOR:
-            tex = texstate->sampler_views[constant->u.State[1]]->base.texture;
-            vec[0] = 1.0 / tex->width0;
-            vec[1] = 1.0 / tex->height0;
+            tex = r300_texture(texstate->sampler_views[constant->u.State[1]]->base.texture);
+            vec[0] = 1.0 / tex->desc.width0;
+            vec[1] = 1.0 / tex->desc.height0;
+            break;
+
+        case RC_STATE_R300_TEXSCALE_FACTOR:
+            tex = r300_texture(texstate->sampler_views[constant->u.State[1]]->base.texture);
+            /* Add a small number to the texture size to work around rounding errors in hw. */
+            vec[0] = tex->desc.b.b.width0  / (tex->desc.width0  + 0.001f);
+            vec[1] = tex->desc.b.b.height0 / (tex->desc.height0 + 0.001f);
+            vec[2] = tex->desc.b.b.depth0  / (tex->desc.depth0  + 0.001f);
             break;
 
         case RC_STATE_R300_VIEWPORT_SCALE: