1 files changed, 20 insertions, 0 deletions
diff --git a/src/gallium/drivers/r300/r300_state_derived.c b/src/gallium/drivers/r300/r300_state_derived.c
index 727ae7ade6..242716fccc 100644
--- a/src/gallium/drivers/r300/r300_state_derived.c
+++ b/src/gallium/drivers/r300/r300_state_derived.c
@@ -410,6 +410,26 @@ static void r300_update_rs_block(struct r300_context* r300,
         }
     }
 
+    /* Rasterize WPOS. */
+    if (vs_outputs->wpos != ATTR_UNUSED) {
+        /* Always rasterize if it's written by the VS,
+         * otherwise it locks up. */
+        rX00_rs_tex(rs, tex_count, tex_count, FALSE);
+
+        /* Write it to the FS input register if it's used by the FS. */
+        if (fs_inputs->wpos != ATTR_UNUSED) {
+            rX00_rs_tex_write(rs, tex_count, fp_offset);
+            fp_offset++;
+        }
+        tex_count++;
+    } else {
+        /* Skip the FS input register, leave it uninitialized. */
+        /* If we try to set it to (0,0,0,1), it will lock up. */
+        if (fs_inputs->wpos != ATTR_UNUSED) {
+            fp_offset++;
+        }
+    }
+
     /* Rasterize at least one color, or bad things happen. */
     if (col_count == 0 && tex_count == 0) {
         rX00_rs_col(rs, 0, 0, TRUE);