diff --git a/include/SSystem/SComponent/c_m3d_g_pla.h b/include/SSystem/SComponent/c_m3d_g_pla.h
index 995d90053..6e9052ba5 100644
--- a/include/SSystem/SComponent/c_m3d_g_pla.h
+++ b/include/SSystem/SComponent/c_m3d_g_pla.h
@@ -24,10 +24,12 @@ public:
     cXyz* GetNP() { return &mNormal; }
     const cXyz* GetNP() const { return &mNormal; }
     f32 GetD() const { return mD; }
-    void getCrossY(const cXyz& i_axis, f32* i_value) const {
-        if (!cM3d_IsZero(mNormal.y)) {
-            *i_value = (-mNormal.x * i_axis.x - mNormal.z * i_axis.z - mD) / mNormal.y;
+    bool getCrossY(const cXyz& i_axis, f32* i_value) const {
+        if (cM3d_IsZero(mNormal.y)) {
+            return false;
         }
+        *i_value = (-mNormal.x * i_axis.x - mNormal.z * i_axis.z - mD) / mNormal.y;
+        return true;
     }
     f32 getCrossY_NonIsZero(const cXyz& i_axis) const {
         return (-mNormal.x * i_axis.x - mNormal.z * i_axis.z - mD) / mNormal.y;
diff --git a/include/d/d_bg_s_sph_chk.h b/include/d/d_bg_s_sph_chk.h
index 7eec9c8f6..5be3dc330 100644
--- a/include/d/d_bg_s_sph_chk.h
+++ b/include/d/d_bg_s_sph_chk.h
@@ -18,7 +18,7 @@ public:
     typedef void(*Callback)(dBgS_SphChk*, cBgD_Vtx_t*, int, int, int, cM3dGPla*, void*);
     void SetCallback(Callback cb) { mpCallback = cb; }
 
-private:
+public:
     /* 0x4c */ Callback mpCallback;
 };  // Size: 0x50
 
diff --git a/src/d/d_bg_w.cpp b/src/d/d_bg_w.cpp
index 96490f1d2..335261acd 100644
--- a/src/d/d_bg_w.cpp
+++ b/src/d/d_bg_w.cpp
@@ -107,8 +107,29 @@ bool dBgW::WallCorrectGrpRp(dBgS_Acch* acch, int grp_id, int depth) {
 }
 
 /* 800A7120-800A72E0       .text RwgRoofChk__4dBgWFUsP12dBgS_RoofChk */
-bool dBgW::RwgRoofChk(u16, dBgS_RoofChk*) {
+bool dBgW::RwgRoofChk(u16 poly_index, dBgS_RoofChk* chk) {
     /* Nonmatching */
+
+    bool ret = false;
+    while (true) {
+        f32 y;
+        if (pm_tri[poly_index].m_plane.getCrossY(*chk->GetPosP(), &y) && chk->GetPosP()->y > y && y < chk->GetNowY()) {
+            cBgD_Tri_t* tri;
+            tri = &pm_bgd->m_t_tbl[poly_index];
+            if (cM3d_CrossY_Tri(pm_vtx_tbl[tri->vtx0], pm_vtx_tbl[tri->vtx1], pm_vtx_tbl[tri->vtx2], pm_tri[poly_index].m_plane, chk->GetPosP()) && !ChkPolyThrough(poly_index, chk->GetPolyPassChk())) {
+                chk->SetNowY(y);
+                chk->SetPolyIndex(poly_index);
+                ret = true;
+            }
+        }
+
+        if (pm_rwg[poly_index].next == 0xFFFF)
+            break;
+
+        poly_index = pm_rwg[poly_index].next;
+    }
+
+    return ret;
 }
 
 /* 800A72E0-800A7514       .text RoofChkRp__4dBgWFP12dBgS_RoofChki */
@@ -176,8 +197,29 @@ bool dBgW::RoofChkGrpRp(dBgS_RoofChk* chk, int grp_id, int depth) {
 }
 
 /* 800A767C-800A783C       .text RwgSplGrpChk__4dBgWFUsP14dBgS_SplGrpChk */
-bool dBgW::RwgSplGrpChk(u16, dBgS_SplGrpChk* chk) {
+bool dBgW::RwgSplGrpChk(u16 poly_index, dBgS_SplGrpChk* chk) {
     /* Nonmatching */
+
+    bool ret = false;
+    while (true) {
+        f32 y;
+        if (pm_tri[poly_index].m_plane.getCrossY(*chk->GetPosP(), &y) && chk->GetPosP()->y > y && y < chk->GetHeight()) {
+            cBgD_Tri_t* tri;
+            tri = &pm_bgd->m_t_tbl[poly_index];
+            if (cM3d_CrossY_Tri(pm_vtx_tbl[tri->vtx0], pm_vtx_tbl[tri->vtx1], pm_vtx_tbl[tri->vtx2], pm_tri[poly_index].m_plane, chk->GetPosP()) && !ChkPolyThrough(poly_index, chk->GetPolyPassChk())) {
+                chk->SetHeight(y);
+                chk->SetPolyIndex(poly_index);
+                ret = true;
+            }
+        }
+
+        if (pm_rwg[poly_index].next == 0xFFFF)
+            break;
+
+        poly_index = pm_rwg[poly_index].next;
+    }
+
+    return ret;
 }
 
 /* 800A783C-800A7A74       .text SplGrpChkRp__4dBgWFP14dBgS_SplGrpChki */
@@ -244,8 +286,36 @@ bool dBgW::SplGrpChkGrpRp(dBgS_SplGrpChk* chk, int grp_id, int depth) {
 }
 
 /* 800A7BDC-800A7DCC       .text RwgSphChk__4dBgWFUsP11dBgS_SphChkPv */
-bool dBgW::RwgSphChk(u16, dBgS_SphChk* chk, void*) {
+bool dBgW::RwgSphChk(u16 poly_index, dBgS_SphChk* chk, void* user) {
     /* Nonmatching */
+    cM3dGTri gtri;
+
+    bool ret = false;
+    while (true) {
+        if (!ChkPolyThrough(poly_index, chk->GetPolyPassChk())) {
+            cBgW_TriElm* tri_elm;
+            cBgD_Tri_t* tri;
+
+            tri = &pm_bgd->m_t_tbl[poly_index];
+            tri_elm = &pm_tri[poly_index];
+
+            gtri.setBg(&pm_vtx_tbl[tri->vtx0], &pm_vtx_tbl[tri->vtx1], &pm_vtx_tbl[tri->vtx2], &tri_elm->m_plane);
+            if (cM3d_Cross_SphTri(chk, &gtri)) {
+                if (chk->mpCallback != NULL) {
+                    chk->mpCallback(chk, (cBgD_Vtx_t*)pm_vtx_tbl, tri->vtx0, tri->vtx1, tri->vtx2, &pm_tri[poly_index].m_plane, user);
+                }
+                chk->SetPolyIndex(poly_index);
+                ret = true;
+            }
+        }
+
+        if (pm_rwg[poly_index].next == 0xFFFF)
+            break;
+
+        poly_index = pm_rwg[poly_index].next;
+    }
+
+    return ret;
 }
 
 /* 800A7DCC-800A8038       .text SphChkRp__4dBgWFP11dBgS_SphChkPvi */