Fix coverage demo launch on Windows: prepend DLL directory to PATH

The demo exe is built into build/examples/<target>/<config>/ but the
Slang runtime DLLs live in build/<config>/bin/. The Windows loader only
searches the exe's own directory, so the process aborts with
STATUS_DLL_NOT_FOUND (0xC0000135).

Derive the DLL directory from the already-located binary path and
prepend it to the child process PATH before launching the demo.
POSIX is unaffected (rpath handles DLL resolution there).

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

Author: jvepsalainen-nv

examples/shader-coverage-bvh-traversal/run_coverage.py

@@ -184,7 +184,14 @@ def main(argv=None):
     binary_cmd = [str(binary), f"--mode={mode}",
                   f"--output-dir={output_dir}", *demo_args]
     print(f"[1/3] running demo: {' '.join(str(a) for a in binary_cmd)}")
-    result = subprocess.run(binary_cmd)
+    # On Windows the runtime DLLs (slang.dll etc.) live in
+    # <build-root>/<config>/bin/, not next to the demo exe. Prepend that
+    # directory to PATH so the loader finds them (otherwise STATUS_DLL_NOT_FOUND).
+    demo_env = os.environ.copy()
+    if platform.system() == "Windows" and len(binary.parents) >= 4:
+        dll_dir = binary.parents[3] / binary.parent.name / "bin"
+        demo_env["PATH"] = str(dll_dir) + os.pathsep + demo_env.get("PATH", "")
+    result = subprocess.run(binary_cmd, env=demo_env)
     if result.returncode != 0:
         sys.exit(f"error: demo exited with code {result.returncode}")
 

examples/shader-coverage-image-pipeline/run_coverage.py

@@ -193,7 +193,14 @@ def main(argv=None):
     binary_cmd = [str(binary), f"--mode={mode}",
                   f"--output-dir={output_dir}", *demo_args]
     print(f"[1/2] running demo: {' '.join(str(a) for a in binary_cmd)}")
-    result = subprocess.run(binary_cmd)
+    # On Windows the runtime DLLs (slang.dll etc.) live in
+    # <build-root>/<config>/bin/, not next to the demo exe. Prepend that
+    # directory to PATH so the loader finds them (otherwise STATUS_DLL_NOT_FOUND).
+    demo_env = os.environ.copy()
+    if platform.system() == "Windows" and len(binary.parents) >= 4:
+        dll_dir = binary.parents[3] / binary.parent.name / "bin"
+        demo_env["PATH"] = str(dll_dir) + os.pathsep + demo_env.get("PATH", "")
+    result = subprocess.run(binary_cmd, env=demo_env)
     if result.returncode != 0:
         sys.exit(f"error: demo exited with code {result.returncode}")