d_envse mostly OK. more work on kankyo_rain (#1969)

* d_envse OK, work on kankyo_rain

* remove asm

include/SSystem/SComponent/c_m3d.h

@@ -3,6 +3,7 @@
 
 #include "MSL_C/math.h"
 #include "dolphin/types.h"
+#include "dolphin/mtx/vec.h"
 
 class cM3dGAab;
 class cM3dGCps;
@@ -95,4 +96,8 @@ inline bool cM3d_IsZero_inverted(f32 param_0) {
     return !(fabsf(param_0) < G_CM3D_F_ABS_MIN);
 }
 
+inline f32 cM3d_LenSq(const Vec* a, const Vec* b) {
+    return VECSquareDistance(a, b);
+}
+
 #endif