Add option to disable libjpeg-turbo.

Instead of always disabling it for Emscripten, when this is really only
need when building for Unity.

Author: kring

CMakeLists.txt

@@ -32,6 +32,7 @@ endif()
 
 option(CESIUM_USE_EZVCPKG "use ezvcpkg helper" ${CESIUM_USE_EZVCPKG_DEFAULT})
 option(CESIUM_DISABLE_CURL "Disable cesium-native's use of libcurl" OFF)
+option(CESIUM_DISABLE_LIBJPEG_TURBO "Disable cesium-native's use of libjpeg-turbo. JPEG images will be decoded with STB instead." OFF)
 option(CESIUM_WASM64 "Enable 64-bit WebAssembly target" OFF)
 
 if (CESIUM_TARGET_WASM)
@@ -126,7 +127,7 @@ set(PACKAGES_PUBLIC asyncplusplus expected-lite fmt glm rapidjson spdlog stb ada
 # OpenSSL and abseil are both dependencies of s2geometry
 set(PACKAGES_PRIVATE
     abseil draco ktx[core] modp-base64 meshoptimizer openssl s2geometry
-    libjpeg-turbo sqlite3 tinyxml2 libwebp zlib-ng picosha2
+    sqlite3 tinyxml2 libwebp zlib-ng picosha2
     earcut-hpp libmorton zstd
 )
 
@@ -142,6 +143,10 @@ if(NOT CESIUM_DISABLE_CURL)
     list(APPEND PACKAGES_PRIVATE curl)
 endif()
 
+if(NOT CESIUM_DISABLE_LIBJPEG_TURBO)
+    list(APPEND PACKAGES_PRIVATE libjpeg-turbo)
+endif()
+
 # We use cpp-httplib to host a local web server for OAuth2 authorization. That's not
 # going to work at all on the web, and the latest versions of cpp-httplib only support
 # 64-bit platforms anyway, so skip it entirely for WebAssembly builds.
@@ -373,7 +378,6 @@ find_package(draco CONFIG REQUIRED)
 find_package(expected-lite CONFIG REQUIRED)
 find_package(glm CONFIG REQUIRED)
 find_package(Ktx CONFIG REQUIRED)
-find_package(libjpeg-turbo CONFIG REQUIRED)
 find_package(libmorton CONFIG REQUIRED)
 find_package(meshoptimizer CONFIG REQUIRED)
 find_package(OpenSSL REQUIRED)
@@ -393,6 +397,10 @@ if(NOT CESIUM_DISABLE_CURL)
     find_package(CURL REQUIRED)
 endif()
 
+if(NOT CESIUM_DISABLE_LIBJPEG_TURBO)
+    find_package(libjpeg-turbo CONFIG REQUIRED)
+endif()
+
 if(NOT CESIUM_TARGET_WASM)
     find_package(httplib CONFIG REQUIRED)
 endif()

CesiumGltfReader/CMakeLists.txt

@@ -62,6 +62,20 @@ target_link_libraries(CesiumGltfReader
         meshoptimizer::meshoptimizer
         modp_b64::modp_b64
         KTX::ktx
-        WebP::webp WebP::webpdecoder
-        $<IF:$<TARGET_EXISTS:libjpeg-turbo::turbojpeg>,libjpeg-turbo::turbojpeg,libjpeg-turbo::turbojpeg-static>
+        WebP::webp
+        WebP::webpdecoder
 )
+
+if(CESIUM_DISABLE_LIBJPEG_TURBO)
+    target_compile_definitions(
+        CesiumGltfReader
+        PRIVATE
+            CESIUM_DISABLE_LIBJPEG_TURBO
+    )
+else()
+    target_link_libraries(
+        CesiumGltfReader
+        PRIVATE
+            $<IF:$<TARGET_EXISTS:libjpeg-turbo::turbojpeg>,libjpeg-turbo::turbojpeg,libjpeg-turbo::turbojpeg-static>
+    )
+endif()

CesiumGltfReader/src/ImageDecoder.cpp

@@ -5,7 +5,6 @@
 #include <CesiumUtility/Tracing.h>
 
 #include <ktx.h>
-#include <turbojpeg.h>
 #include <webp/decode.h>
 
 #include <algorithm>
@@ -28,6 +27,10 @@
 #define STB_IMAGE_RESIZE_STATIC
 #include <stb_image_resize2.h>
 
+#ifndef CESIUM_DISABLE_LIBJPEG_TURBO
+#include <turbojpeg.h>
+#endif
+
 namespace CesiumGltfReader {
 
 using namespace CesiumGltf;
@@ -287,7 +290,7 @@ ImageReaderResult ImageDecoder::readImage(
   }
 
   {
-#ifndef __EMSCRIPTEN__ // Conflict between turbojpeg and Unity
+#ifndef CESIUM_DISABLE_LIBJPEG_TURBO
     tjhandle tjInstance = tjInitDecompress();
     int inSubsamp, inColorspace;
     if (!tjDecompressHeader3(
@@ -318,7 +321,7 @@ ImageReaderResult ImageDecoder::readImage(
         result.pImage = nullptr;
       }
     } else
-#endif // __EMSCRIPTEN__
+#endif // !CESIUM_DISABLE_LIBJPEG_TURBO
     {
       CESIUM_TRACE("Decode PNG");
       image.bytesPerChannel = 1;
@@ -352,9 +355,9 @@ ImageReaderResult ImageDecoder::readImage(
         result.errors.emplace_back(stbi_failure_reason());
       }
     }
-#ifndef __EMSCRIPTEN__
+#ifndef CESIUM_DISABLE_LIBJPEG_TURBO
     tjDestroy(tjInstance);
-#endif // __EMSCRIPTEN__
+#endif
   }
   return result;
 }