Area: Implement ExtForceArea (#931)

data/file_list.yml

@@ -1025,19 +1025,19 @@ Area/ExtForceArea.o:
   - offset: 0x00546c
     size: 88
     label: _ZN12ExtForceAreaC2EPKc
-    status: NotDecompiled
+    status: Matching
   - offset: 0x0054c4
     size: 100
     label: _ZN12ExtForceAreaC1EPKc
-    status: NotDecompiled
+    status: Matching
   - offset: 0x005528
     size: 156
     label: _ZN12ExtForceArea4initERKN2al12AreaInitInfoE
-    status: NotDecompiled
+    status: Matching
   - offset: 0x0055c4
     size: 640
     label: _ZNK12ExtForceArea12calcExtForceEPN4sead7Vector3IfEERKS2_S5_S5_
-    status: NotDecompiled
+    status: Matching
 Area/ForceRecoveryKidsArea.o:
   '.text':
   - offset: 0x005844

src/Area/ExtForceArea.cpp

@@ -0,0 +1,76 @@
+#include "Area/ExtForceArea.h"
+
+#include "Library/Area/AreaInitInfo.h"
+#include "Library/Area/AreaObjUtil.h"
+#include "Library/Base/StringUtil.h"
+#include "Library/Math/MathUtil.h"
+#include "Library/Placement/PlacementFunction.h"
+
+ExtForceArea::ExtForceArea(const char* name) : al::AreaObj(name) {}
+
+void ExtForceArea::init(const al::AreaInitInfo& info) {
+    al::AreaObj::init(info);
+
+    const char* forceType = "Normal";
+    if (!al::tryGetStringArg(&forceType, static_cast<const al::PlacementInfo&>(info), "ForceType"))
+        return;
+
+    if (al::isEqualString(forceType, "Normal")) {
+        mSpeedVStep = 2.0f;
+        mSpeedVTarget = -40.0f;
+        mForceH = 0.98f;
+    } else if (al::isEqualString(forceType, "Weak")) {
+        mSpeedVStep = 0.25f;
+        mSpeedVTarget = -40.0f;
+        mForceH = 0.98f;
+    }
+}
+
+void ExtForceArea::calcExtForce(sead::Vector3f* force, const sead::Vector3f& pos,
+                                const sead::Vector3f& prevForce,
+                                const sead::Vector3f& velocity) const {
+    force->set(0.0f, 0.0f, 0.0f);
+
+    if (!isInVolume(pos))
+        return;
+
+    sead::Vector3f dirUp = {0.0f, 0.0f, 0.0f};
+    al::getAreaObjDirUp(&dirUp, this);
+
+    sead::Vector3f velH = {0.0f, 0.0f, 0.0f};
+    sead::Vector3f velV = {0.0f, 0.0f, 0.0f};
+    al::separateVectorHV(&velH, &velV, dirUp, velocity);
+
+    sead::Vector3f prevForceH = {0.0f, 0.0f, 0.0f};
+    sead::Vector3f prevForceV = {0.0f, 0.0f, 0.0f};
+    al::separateVectorHV(&prevForceH, &prevForceV, dirUp, prevForce);
+
+    f32 speedV = dirUp.dot(velV);
+    f32 prevForceMagnitudeV = dirUp.dot(prevForceV);
+
+    // --- Vertical force ---
+    sead::Vector3f forceV;
+
+    if (al::isSameSign(speedV, mSpeedVTarget) &&
+        sead::Mathf::abs(speedV) > sead::Mathf::abs(mSpeedVTarget)) {
+        forceV = dirUp * (-prevForceMagnitudeV);
+    } else {
+        f32 curSpeedV = speedV + prevForceMagnitudeV;
+        f32 newSpeedV = al::converge(curSpeedV, mSpeedVTarget, mSpeedVStep);
+        forceV = dirUp * (newSpeedV - curSpeedV);
+    }
+
+    // --- Horizontal force ---
+    sead::Vector3f dirVelH = {0.0f, 0.0f, 0.0f};
+    sead::Vector3f forceH;
+
+    if (al::tryNormalizeOrZero(&dirVelH, velH)) {
+        f32 diff = velH.length() - prevForceH.length();
+        f32 forceMag = sead::Mathf::clampMin(diff, 0.0f) * mForceH;
+        forceH = (dirVelH * forceMag) - (prevForceH + velH);
+    } else {
+        forceH = -prevForceH;
+    }
+
+    force->setAdd(forceV, forceH);
+}

src/Area/ExtForceArea.h

@@ -8,10 +8,11 @@ public:
 
     void init(const al::AreaInitInfo& info) override;
 
-    void calcExtForce(sead::Vector3f*, const sead::Vector3f&, const sead::Vector3f&,
-                      const sead::Vector3f&) const;
+    void calcExtForce(sead::Vector3f* force, const sead::Vector3f& pos,
+                      const sead::Vector3f& prevForce, const sead::Vector3f& velocity) const;
 
 private:
-    sead::Vector2f mUnknown;
-    f32 mMagnitude = 1.0;
+    f32 mSpeedVStep = 0.0f;
+    f32 mSpeedVTarget = 0.0f;
+    f32 mForceH = 1.0f;
 };