From 47ab0a9d026a62c1cb3e0f37aa00927da5bed348 Mon Sep 17 00:00:00 2001
From: alessamothdream <mothdreams666@gmail.com>
Date: Thu, 20 Aug 2026 22:50:35 -0700
Subject: [PATCH] begin `MathUtil.c`, migrate data

---
 config/kuon.yaml              |  2 +-
 include/common.h              | 11 +++--
 src/cs4/Seimei/src/MathUtil.c | 79 ++++++++++++++++++++++++++++++++---
 3 files changed, 83 insertions(+), 9 deletions(-)

diff --git a/config/kuon.yaml b/config/kuon.yaml
index c259220..0538828 100644
--- a/config/kuon.yaml
+++ b/config/kuon.yaml
@@ -848,7 +848,7 @@ segments:
         - { vram: 0x003254B0, type: .bss, name: cs4/Seimei/src/File}
         - { vram: 0x003255B0, type: .bss, name: cs4/Seimei/src/Load}
         - { vram: 0x003A5E10, type: .bss, name: cs4/Seimei/src/Main}
-        # - { vram: 0x003A5E40, type: .bss, name: cs4/Seimei/src/Model} # maybe MathUtil?
+        - { vram: 0x003A5E40, type: .bss, name: cs4/Seimei/src/MathUtil}
         - { vram: 0x003A5E50, type: .bss, name: cs4/Seimei/src/Model}
         - { vram: 0x006F51D0, type: .bss, name: cs4/Seimei/src/Pad}
         - { vram: 0x006F5390, type: .bss, name: cs4/Seimei/src/Sprite}
diff --git a/include/common.h b/include/common.h
index 6a66e81..0c2ce1b 100644
--- a/include/common.h
+++ b/include/common.h
@@ -18,10 +18,15 @@
 #define ARRAY_COUNT(arr) (s32)(sizeof(arr) / sizeof(arr[0]))
 #define ARRAY_COUNTU(arr) (u32)(sizeof(arr) / sizeof(arr[0]))
 
-// #define PI 3.1415928f
+#define PI 3.1415927f
+#define HALF_PI 1.5707964f
+#define TWO_PI 6.2831855f
 
-f32 cosf(f32);
-f32 atan2f(f32, f32);
+float atan2f(float, float);
+float atanf(float);
+float cosf(float);
+float sinf(float);
+float sqrtf(float);
 
 #define BSS __attribute__ ((section (".bss")))
 
diff --git a/src/cs4/Seimei/src/MathUtil.c b/src/cs4/Seimei/src/MathUtil.c
index 4358b8c..35bc6cb 100644
--- a/src/cs4/Seimei/src/MathUtil.c
+++ b/src/cs4/Seimei/src/MathUtil.c
@@ -1,5 +1,20 @@
 #include "common.h"
 
+#define REVOLUTIONS(angle) (TWO_PI * (int) ((PI + angle) / TWO_PI))
+
+float V0[4]; // size: 0x10, address: 0x3A5E40
+float V1[4] = {1.0, 1.0, 1.0, 1.0}; // size: 0x10, address: 0x2286F0
+float VX[4] = {1.0, 0.0, 0.0, 0.0}; // size: 0x10, address: 0x228700
+float VY[4] = {0.0, 1.0, 0.0, 0.0}; // size: 0x10, address: 0x228710
+float VZ[4] = {0.0, 0.0, 1.0, 0.0}; // size: 0x10, address: 0x228720
+float VW[4] = {0.0, 0.0, 0.0, 1.0}; // size: 0x10, address: 0x228730
+float MRX1[4][4] = {
+    {1.0, 0.0, 0.0, 0.0},
+    {0.0, 1.0, 0.0, 0.0},
+    {0.0, 0.0, 1.0, 0.0},
+    {0.0, 0.0, 0.0, 1.0},
+}; // size: 0x40, address: 0x228740
+
 INCLUDE_ASM("config/asm/nonmatchings/cs4/Seimei/src/MathUtil", Math_GetPosToAngle);
 
 INCLUDE_ASM("config/asm/nonmatchings/cs4/Seimei/src/MathUtil", Math_GotoVector2);
@@ -10,16 +25,70 @@ INCLUDE_ASM("config/asm/nonmatchings/cs4/Seimei/src/MathUtil", Math_GotoVectorXZ
 
 INCLUDE_ASM("config/asm/nonmatchings/cs4/Seimei/src/MathUtil", Math_GetAngleDist);
 
-INCLUDE_ASM("config/asm/nonmatchings/cs4/Seimei/src/MathUtil", Math_GetAngle360);
+float Math_GetAngle360(float ang) {
+    return ang >= 0.0f ? ang : ang + TWO_PI;
 
-INCLUDE_ASM("config/asm/nonmatchings/cs4/Seimei/src/MathUtil", Math_GetDistXZ);
+}
 
-INCLUDE_ASM("config/asm/nonmatchings/cs4/Seimei/src/MathUtil", Math_GetDist2);
+float Math_GetDistXZ(float* v1, float* v2) {
+    float dx;
+    float dz;
+    float dd;
+
+    dx = v2[0] - v1[0];
+    dz = v2[2] - v1[2];
+    dd = sqrtf(dx * dx + dz * dz);
+
+    return dd;
+}
+
+float Math_GetDist2(float* v1, float* v2) {
+    float dx;
+    float dy;
+    float dz;
+
+    dx = v2[0] - v1[0];
+    dy = v2[1] - v1[1];
+    dz = v2[2] - v1[2];
+
+    return dx * dx + dy * dy + dz * dz;
+}
 
 INCLUDE_ASM("config/asm/nonmatchings/cs4/Seimei/src/MathUtil", Math_GetDist);
 
 INCLUDE_ASM("config/asm/nonmatchings/cs4/Seimei/src/MathUtil", Math_GotoAngle);
 
-INCLUDE_ASM("config/asm/nonmatchings/cs4/Seimei/src/MathUtil", Math_VectorToAngleXY);
+void Math_VectorToAngleXY(float* Ang, float* Vec) {
+    float dist = sqrtf(Vec[0] * Vec[0] + Vec[2] * Vec[2]);
 
-INCLUDE_ASM("config/asm/nonmatchings/cs4/Seimei/src/MathUtil", Math_VectorToAngle);
+    if (dist == 0.0f) {
+        if (Vec[1] < 0.0f) Ang[0] = HALF_PI;
+        else if (Vec[1] > 0.0f) Ang[0] = -HALF_PI;
+        else Ang[0] = 0.0f;
+    } else {
+        // treat distance as x-axis
+        Ang[0] = atanf(-Vec[1] / dist);
+    }
+    
+    Ang[1] = atan2f(Vec[0], Vec[2]);
+    Ang[3] = Ang[2] = 0;
+}
+
+float Math_VectorToAngle(float xx, float zz) {
+    float Angle;
+ 
+    if (zz != 0.0f) {
+        Angle = atanf(xx / -zz);
+        
+        if (-zz > 0.0f) {
+            if (xx > 0.0f) Angle -= PI;
+            else Angle += PI;
+        }
+    }
+        
+    else if (xx > 0.0f) Angle = -HALF_PI;
+    else Angle = HALF_PI;
+
+    if (PI - Angle >= 0.0f) return -Angle - REVOLUTIONS(-Angle);
+    return TWO_PI + (-Angle - REVOLUTIONS(-Angle));
+}