Initial public release of rem-essentials

third_party/flsharp/src/weapon_anim.cpp

@@ -0,0 +1,89 @@
+#include "weapon_anim.h"
+#include "utils.h"
+#include "fl_func.h"
+#include "logger.h"
+
+DWORD setModelCallAddr = 0;
+
+FL_FUNC(bool EngAnimation::SetModel(PDWORD unk, const EngModel* model), setModelCallAddr);
+
+// There exist many animations for the weapon models in Freelancer (e.g. barrels rotating or moving back and forth while shooting).
+// However, despite all weapon animations already being defined correctly in the ini files, there is a bug in engbase.dll that prevents these animations from playing properly.
+// In vanilla FL the internal weapon animation structs have their model set to their actual gun, but this way they don't work.
+// The fix is to set the animation structs model to its parent (the ship hull). With this the animations will play correctly.
+bool EngAnimation::SetModel_Hook(PDWORD unk, const EngModel* model)
+{
+    const EngModel* currentModel = model;
+
+    // Find the parent (ship hull) of the weapon model.
+    while (currentModel)
+    {
+        // If the parent has been found, ensure this is used as the model for the animation, but keep checking for greater parents.
+        if (currentModel->type == EngModelType::Object)
+        {
+            model = currentModel;
+        }
+
+        currentModel = currentModel->parent;
+    }
+
+    // Call original function.
+    return SetModel(unk, model);
+}
+
+// This hook allows for e.g. the Cruiser forward gun animation to work without having to modify the model.
+// Normally in FL the gun .cmp files have their gun animation included.
+// However, the cruiser gun model is part of the Cruiser ship model itself, and thus the animation is also in the ship model.
+// In vanilla FL it's not possible to call ship animations when firing a gun.
+// This hook allows an animation to be played on the parent of the gun if there is a leading underscore in the animation name (_).
+int IAnimation2::Open_Hook(LPCSTR animationScript, int scriptIndex, const CAttachedEquip &equip)
+{
+    // If the animation script has a leading underscore, open the animation on the parent of the equipment.
+    if (animationScript && animationScript[0] == '_')
+    {
+        // Remove the leading underscore.
+        // One could argue removing a leading underscore like this is bad practice
+        // since the address is no longer DWORD-aligned.
+        // However, these string addresses aren't DWORD-aligned out of the box, so it doesn't matter.
+        ++animationScript;
+
+        if (CObject* parent = equip.parent)
+        {
+            // Open the animation on the parent.
+            return Open(parent->get_archetype()->scriptIndex, parent->engineInstance, animationScript);
+        }
+    }
+
+    // Open the animation on the attached equipment (normal routine).
+    return Open(scriptIndex, equip.GetRootIndex(), animationScript);
+}
+
+// Fixes the weapon animations and allows weapons to play ship animations (e.g. wings).
+void InitWeaponAnimFix()
+{
+    #define SET_MODEL_FUNC_FILE_OFFSET_ENGBASE 0xADC0
+    #define SET_MODEL_CALL_FILE_OFFSET_ENGBASE 0xB83F
+    #define GET_ROOT_INDEX_CALL_ADDR 0x52C8AF
+    #define PUSH_ZERO_ADDR 0x52C8BF
+    #define ANIM_OPEN_CALL_ADDR 0x52C8C2
+
+    DWORD engbaseHandle = (DWORD) GetModuleHandle("engbase.dll");
+
+    if (engbaseHandle)
+    {
+        setModelCallAddr = engbaseHandle + SET_MODEL_FUNC_FILE_OFFSET_ENGBASE;
+        Hook(engbaseHandle + SET_MODEL_CALL_FILE_OFFSET_ENGBASE, &EngAnimation::SetModel_Hook, 5);
+    }
+    else
+    {
+        Logger::PrintModuleError("InitWeaponAnimFix", "engbase.dll");
+    }
+
+    // Setup for IAnimation2::Open hook
+    Patch<WORD>(GET_ROOT_INDEX_CALL_ADDR, 0x5551); // Replace GetRootIndex call with push ecx + push ebx
+    Nop(GET_ROOT_INDEX_CALL_ADDR + 2, 4);
+    Nop(PUSH_ZERO_ADDR, 2); // Nop out two zero pushes
+    Nop(ANIM_OPEN_CALL_ADDR, 1); // Nop another instruction
+
+    Hook(ANIM_OPEN_CALL_ADDR + 1, &IAnimation2::Open_Hook, 5);
+}