examples: fix shader-coverage demo portability (#11623)

The two shader-coverage demos relied entirely on find_package(Vulkan)
for both the loader and headers, and skipped themselves if either was
missing. This left them unbuildable on machines that ship only the
Vulkan runtime loader (no -dev/SDK package) and on older Vulkan headers.

- CMakeLists: source headers from Slang's bundled Vulkan::Headers
target, and fall back to locating the runtime loader (libvulkan.so.1)
when find_package(Vulkan) is unavailable, instead of skipping the
example.
- vk_compute_demo.cpp: guard the VK_KHR_portability_enumeration
references behind #if defined so headers older than 1.3.x still compile.

Author: jvepsalainen-nv

examples/shader-coverage-bvh-traversal/CMakeLists.txt

@@ -3,13 +3,25 @@
 # See the image-pipeline demo's CMakeLists.txt for the rationale on
 # why this example uses raw Vulkan instead of slang-rhi.
 
-find_package(Vulkan)
-if(NOT Vulkan_FOUND)
-    message(
-        STATUS
-        "examples: skipping shader-coverage-bvh-traversal (Vulkan SDK not found)"
-    )
-    return()
+# Vulkan headers come from Slang's bundled Vulkan-Headers submodule (the
+# always-available Vulkan::Headers target, see external/CMakeLists.txt), so
+# this demo only needs to locate the loader library at build time. Prefer the
+# Vulkan SDK's imported target when present; otherwise fall back to the bare
+# runtime loader (e.g. libvulkan.so.1) so the demo still builds on machines
+# that ship only the Vulkan runtime and not a -dev/SDK package.
+find_package(Vulkan QUIET)
+if(TARGET Vulkan::Vulkan)
+    set(_vulkan_loader Vulkan::Vulkan)
+else()
+    find_library(SLANG_VULKAN_LOADER NAMES vulkan vulkan-1 libvulkan.so.1)
+    if(NOT SLANG_VULKAN_LOADER)
+        message(
+            STATUS
+            "examples: skipping shader-coverage-bvh-traversal (Vulkan loader not found)"
+        )
+        return()
+    endif()
+    set(_vulkan_loader ${SLANG_VULKAN_LOADER})
 endif()
 
 set(_asset_files
@@ -53,7 +65,7 @@ target_include_directories(
 )
 target_link_libraries(
     shader-coverage-bvh-traversal
-    PRIVATE Vulkan::Vulkan slang core
+    PRIVATE ${_vulkan_loader} Vulkan::Headers slang core
 )
 target_compile_features(shader-coverage-bvh-traversal PRIVATE cxx_std_17)
 set_target_properties(shader-coverage-bvh-traversal PROPERTIES FOLDER examples)

examples/shader-coverage-bvh-traversal/vk_compute_demo.cpp

@@ -6,6 +6,16 @@
 
 #include <cstring>
 
+// VK_KHR_portability_enumeration was introduced in Vulkan SDK 1.3.x headers.
+// Define string and flag fallbacks so the runtime detection below compiles
+// against any SDK version; both values are fixed by the Vulkan spec.
+#ifndef VK_KHR_PORTABILITY_ENUMERATION_EXTENSION_NAME
+#define VK_KHR_PORTABILITY_ENUMERATION_EXTENSION_NAME "VK_KHR_portability_enumeration"
+#endif
+#ifndef VK_INSTANCE_CREATE_ENUMERATE_PORTABILITY_BIT_KHR
+#define VK_INSTANCE_CREATE_ENUMERATE_PORTABILITY_BIT_KHR ((VkInstanceCreateFlagBits)0x00000001)
+#endif
+
 namespace vkdemo
 {
 

examples/shader-coverage-image-pipeline/CMakeLists.txt

@@ -10,13 +10,25 @@
 # Requires Vulkan SDK at build time for the loader (libvulkan).
 # Headers come from Slang's Vulkan-Headers submodule.
 
-find_package(Vulkan)
-if(NOT Vulkan_FOUND)
-    message(
-        STATUS
-        "examples: skipping shader-coverage-image-pipeline (Vulkan SDK not found)"
-    )
-    return()
+# Vulkan headers come from Slang's bundled Vulkan-Headers submodule (the
+# always-available Vulkan::Headers target, see external/CMakeLists.txt), so
+# this demo only needs to locate the loader library at build time. Prefer the
+# Vulkan SDK's imported target when present; otherwise fall back to the bare
+# runtime loader (e.g. libvulkan.so.1) so the demo still builds on machines
+# that ship only the Vulkan runtime and not a -dev/SDK package.
+find_package(Vulkan QUIET)
+if(TARGET Vulkan::Vulkan)
+    set(_vulkan_loader Vulkan::Vulkan)
+else()
+    find_library(SLANG_VULKAN_LOADER NAMES vulkan vulkan-1 libvulkan.so.1)
+    if(NOT SLANG_VULKAN_LOADER)
+        message(
+            STATUS
+            "examples: skipping shader-coverage-image-pipeline (Vulkan loader not found)"
+        )
+        return()
+    endif()
+    set(_vulkan_loader ${SLANG_VULKAN_LOADER})
 endif()
 
 set(_asset_files denoise.slang gamma.slang pipeline.slang tonemap.slang)
@@ -55,7 +67,7 @@ target_include_directories(
 )
 target_link_libraries(
     shader-coverage-image-pipeline
-    PRIVATE Vulkan::Vulkan slang core
+    PRIVATE ${_vulkan_loader} Vulkan::Headers slang core
 )
 target_compile_features(shader-coverage-image-pipeline PRIVATE cxx_std_17)
 set_target_properties(shader-coverage-image-pipeline PROPERTIES FOLDER examples)

examples/shader-coverage-image-pipeline/vk_compute_demo.cpp

@@ -6,6 +6,16 @@
 
 #include <cstring>
 
+// VK_KHR_portability_enumeration was introduced in Vulkan SDK 1.3.x headers.
+// Define string and flag fallbacks so the runtime detection below compiles
+// against any SDK version; both values are fixed by the Vulkan spec.
+#ifndef VK_KHR_PORTABILITY_ENUMERATION_EXTENSION_NAME
+#define VK_KHR_PORTABILITY_ENUMERATION_EXTENSION_NAME "VK_KHR_portability_enumeration"
+#endif
+#ifndef VK_INSTANCE_CREATE_ENUMERATE_PORTABILITY_BIT_KHR
+#define VK_INSTANCE_CREATE_ENUMERATE_PORTABILITY_BIT_KHR ((VkInstanceCreateFlagBits)0x00000001)
+#endif
+
 namespace vkdemo
 {