wrapper: give cmake CUDA explicitly (needed to configure) by SoC arch

The wrapper enables the CUDA language, so it will not configure without a working
CUDA — even though libk4arecord_v2.so does not use it. A non-interactive shell
has no cuda/bin on PATH, so point cmake at nvcc and pass the architecture derived
from the SoC (Orin = sm_87).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

scripts/build_k4a_wrapper.sh

@@ -22,6 +22,29 @@ eval "$("$here/detect_platform.sh")"
 REPO_URL="${OB_K4A_REPO:-https://github.com/orbbec/OrbbecSDK-K4A-Wrapper}"
 REF="${OB_K4A_REF:-v1.10.4}"
 
+# The wrapper enables the CUDA language (its bundled OrbbecSDK does), so it will
+# not even CONFIGURE without a working CUDA — regardless of libk4arecord_v2.so not
+# using it. A non-interactive shell has no cuda/bin on PATH, so point cmake at it
+# and give the architecture by SoC (cmake needs it explicit here). Empty when no
+# CUDA is found, letting cmake try its own detection.
+cuda_flags() {
+    local nvcc
+    for nvcc in /usr/local/cuda/bin/nvcc /usr/local/cuda-*/bin/nvcc; do
+        [[ -x "$nvcc" ]] && break
+    done
+    [[ -x "$nvcc" ]] || return 0
+    local arch
+    case "$SOC" in
+        tegra210) arch=53 ;;   # Nano, TX1
+        tegra186) arch=62 ;;   # TX2
+        tegra194) arch=72 ;;   # Xavier
+        tegra234) arch=87 ;;   # Orin
+        tegra264) arch=101 ;;  # Thor
+        *)        arch=87 ;;   # a reasonable modern default
+    esac
+    printf -- '-DCMAKE_CUDA_COMPILER=%s -DCMAKE_CUDA_ARCHITECTURES=%s' "$nvcc" "$arch"
+}
+
 # A usable wrapper base: headers and the stock libk4a. The v2 target is ensured
 # separately, so a wrapper built before this repo existed still qualifies.
 find_wrapper() {
@@ -49,7 +72,7 @@ ensure_recordv2() {
     fi
 
     ( cd "$d/build"
-      cmake .. -DCMAKE_BUILD_TYPE=Release >&2
+      cmake .. -DCMAKE_BUILD_TYPE=Release $(cuda_flags) >&2
       make -j"$(nproc)" k4arecord_v2 >&2 )
 
     [[ -f "$d/build/lib/libk4arecord_v2.so" ]]
@@ -82,7 +105,7 @@ fi
 
 mkdir -p "$dir/build"
 ( cd "$dir/build"
-  cmake .. -DCMAKE_BUILD_TYPE=Release >&2
+  cmake .. -DCMAKE_BUILD_TYPE=Release $(cuda_flags) >&2
   make -j"$(nproc)" k4a k4arecord >&2 )
 
 if ! find_wrapper "$dir" >/dev/null 2>&1 || ! ensure_recordv2 "$dir"; then