Alt Toggle for Custom animation (#6433)

Add explicit alt prefix checking to animation loading

Makes ResourceMgr_LoadAnimByName alt-toggleable this will work for Link and any other animations files

soh/soh/ResourceManagerHelpers.cpp

@@ -517,7 +517,47 @@ extern "C" int ResourceMgr_OTRSigCheck(char* imgData) {
     return 0;
 }
 
+// Load animation with explicit alt asset path checking.
+// When Alt Assets is OFF: use original path directly (O2R or vanilla)
+// When Alt Assets is ON: try alt/ prefix first, fall back to regular path if not found or invalid
 extern "C" AnimationHeaderCommon* ResourceMgr_LoadAnimByName(const char* path) {
+    bool isAlt = ResourceMgr_IsAltAssetsEnabled();
+
+    if (isAlt) {
+        std::string pathStr = std::string(path);
+        static const std::string sOtr = "__OTR__";
+
+        if (pathStr.starts_with(sOtr)) {
+            pathStr = pathStr.substr(sOtr.length());
+        }
+
+        // Try alt/ first
+        pathStr = Ship::IResource::gAltAssetPrefix + pathStr;
+        AnimationHeaderCommon* animHeader = (AnimationHeaderCommon*)ResourceGetDataByName(pathStr.c_str());
+
+        // If alt loaded successfully, verify it has valid data
+        if (animHeader != NULL) {
+            // Check for valid frame count (> 0)
+            if (animHeader->frameCount > 0) {
+                // For Normal animations: check frameData (comes after frameCount in AnimationHeader)
+                // For Link animations: check segment (comes after frameCount in LinkAnimationHeader)
+                // We check both to be safe - if either is valid, the animation is usable
+                AnimationHeader* normalAnim = (AnimationHeader*)animHeader;
+                LinkAnimationHeader* linkAnim = (LinkAnimationHeader*)animHeader;
+
+                // Valid if Normal animation has frameData OR Link animation has segment
+                if (normalAnim->frameData != NULL || linkAnim->segment != NULL) {
+                    return animHeader;
+                }
+            }
+            // Alt loaded but is invalid (broken), fall through to original path
+        }
+
+        // Fall back to original path
+        return (AnimationHeaderCommon*)ResourceGetDataByName(path);
+    }
+
+    // Alt OFF: use original path directly
     return (AnimationHeaderCommon*)ResourceGetDataByName(path);
 }
 

soh/soh/resource/importer/AnimationFactory.cpp

@@ -78,15 +78,33 @@ ResourceFactoryBinaryAnimationV0::ReadResource(std::shared_ptr<Ship::File> file,
         }
         animation->animationData.transformUpdateIndex.copyValues = animation->copyValuesArr.data();
     } else if (animType == AnimationType::Link) {
+        // Initialize segment to nullptr (important for alt asset fallback)
+        animation->animationData.linkAnimationHeader.segment = nullptr;
+
         // Read the frame count
         animation->animationData.linkAnimationHeader.common.frameCount = reader->ReadInt16();
 
         // Read the segment pointer (always 32 bit, doesn't adjust for system pointer size)
         std::string path = reader->ReadString();
-        const auto animData = std::static_pointer_cast<Animation>(
+        auto animData = std::static_pointer_cast<Animation>(
             Ship::Context::GetInstance()->GetResourceManager()->LoadResourceProcess(path.c_str()));
 
-        animation->animationData.linkAnimationHeader.segment = animData->GetPointer();
+        // If direct load failed and alt assets are enabled, try with alt/ prefix
+        if (animData == nullptr && Ship::Context::GetInstance()->GetResourceManager()->IsAltAssetsEnabled()) {
+            std::string altPath = path;
+            if (altPath.find("__OTR__") == 0) {
+                altPath = altPath.substr(7); // Strip __OTR__
+            }
+            altPath = "alt/" + altPath;
+            animData = std::static_pointer_cast<Animation>(
+                Ship::Context::GetInstance()->GetResourceManager()->LoadResourceProcess(altPath.c_str()));
+        }
+
+        if (animData != nullptr) {
+            animation->animationData.linkAnimationHeader.segment = animData->GetPointer();
+        } else {
+            SPDLOG_WARN("Animation data segment not found: {}", path);
+        }
     } else if (animType == AnimationType::Legacy) {
         SPDLOG_DEBUG("BEYTAH ANIMATION?!");
     }

soh/src/code/z_skelanime.c

@@ -902,6 +902,10 @@ void AnimationContext_SetLoadFrame(PlayState* play, LinkAnimationHeader* animati
         if (frame < 0) {
             frame = 0;
         }
+        // SOH [Alt Assets] Check if animData is null (can happen if animation data segment failed to load)
+        if (animData == NULL) {
+            return;
+        }
         memcpy(ram, (uintptr_t)animData + (((sizeof(Vec3s) * limbCount + 2) * frame)), sizeof(Vec3s) * limbCount + 2);
     }
 }