diff --git a/Makefile b/Makefile
index 9418d988..9dc3d28a 100644
--- a/Makefile
+++ b/Makefile
@@ -82,7 +82,7 @@ endif
 
 ### Compiler ###
 
-CC              := $(TOOLS)/ido_recomp/$(DETECTED_OS)/5.3/cc
+IDO              := $(TOOLS)/ido_recomp/$(DETECTED_OS)/5.3/cc
 AS              := $(MIPS_BINUTILS_PREFIX)as
 LD              := $(MIPS_BINUTILS_PREFIX)ld
 OBJCOPY         := $(MIPS_BINUTILS_PREFIX)objcopy
@@ -194,10 +194,12 @@ build/src/libultra/2D300.o: OPTFLAGS := -O1 -g0
 build/src/libultra/io/controller.o: OPTFLAGS := -O1 -g0
 build/src/libultra/libc/string.o: OPTFLAGS := -O2 -g0
 build/src/libultra/libc/ldiv.o: OPTFLAGS := -O2 -g0
-#build/src/libultra/gu/lookat.o: OPTFLAGS := -O3 -g0
+build/src/libultra/gu/lookat.o: OPTFLAGS := -O3 -g0
 
 # cc & asm-processor
-build/src/%.o: CC := $(ASM_PROC) $(ASM_PROC_FLAGS) $(CC) -- $(AS) $(ASFLAGS) --
+CC := $(ASM_PROC) $(ASM_PROC_FLAGS) $(IDO) -- $(AS) $(ASFLAGS) --
+build/src/libultra/gu/lookat.o: CC := $(IDO)
+#build/src/%.o: CC := $(ASM_PROC) $(ASM_PROC_FLAGS) $(IDO) -- $(AS) $(ASFLAGS) --
 
 all: uncompressed
 
diff --git a/diff_settings.py b/diff_settings.py
index 192cce88..ca3a3797 100644
--- a/diff_settings.py
+++ b/diff_settings.py
@@ -2,7 +2,7 @@
 
 def apply(config, args):
     config['baseimg'] = 'baserom.us.z64'
-    config['myimg'] = 'build/starfox64.us.z64'
+    config['myimg'] = 'build/starfox64.us.uncompressed.z64'
     config['mapfile'] = 'build/starfox64.us.map'
     config['source_directories'] = ['./src','./include']
     config['objdump_flags'] = ['-M','reg-names=32']
diff --git a/include/PR/ultratypes.h b/include/PR/ultratypes.h
index 6af7c9ff..6bc4c650 100644
--- a/include/PR/ultratypes.h
+++ b/include/PR/ultratypes.h
@@ -59,6 +59,8 @@ typedef double				f64;	/* double prec floating point */
 
 typedef u32 size_t;
 
+typedef float Matrix[4][4];
+
 #endif  /* _LANGUAGE_C */
 
 
diff --git a/include/macros.h b/include/macros.h
index 424291b7..1a5ab1f4 100644
--- a/include/macros.h
+++ b/include/macros.h
@@ -2,5 +2,6 @@
 #define MACROS_H
 
 #define ARRAY_COUNT(arr) (s32)(sizeof(arr) / sizeof(arr[0]))
+#define SQ(x) ((x) * (x))
 
 #endif // MACROS_H
diff --git a/src/libultra/gu/lookat.c b/src/libultra/gu/lookat.c
index e66f3fc1..a1829777 100644
--- a/src/libultra/gu/lookat.c
+++ b/src/libultra/gu/lookat.c
@@ -1,11 +1,73 @@
 #include "global.h"
 #include "PR/gbi.h"
 
-typedef float Matrix[4][4];
+void guMtxIdentF(float (*mf)[4]);
 
-#pragma GLOBAL_ASM("asm/us/nonmatchings/libultra/gu/lookat/guLookAtF.s")
+float sqrtf(float value);
+
+void guLookAtF(float mf[4][4], float xEye, float yEye, float zEye, float xAt, float yAt, float zAt, float xUp,
+               float yUp, float zUp) {
+    float len;
+    float xLook;
+    float yLook;
+    float zLook;
+    float xRight;
+    float yRight;
+    float zRight;
+
+    guMtxIdentF(mf);
+
+    xLook = xAt - xEye;
+    yLook = yAt - yEye;
+    zLook = zAt - zEye;
+
+    /* Negate because positive Z is behind us: */
+    len = -1.0 / sqrtf(xLook * xLook + yLook * yLook + zLook * zLook);
+    xLook *= len;
+    yLook *= len;
+    zLook *= len;
+
+    /* Right = Up x Look */
+
+    xRight = yUp * zLook - zUp * yLook;
+    yRight = zUp * xLook - xUp * zLook;
+    zRight = xUp * yLook - yUp * xLook;
+    len = 1.0 / sqrtf(xRight * xRight + yRight * yRight + zRight * zRight);
+    xRight *= len;
+    yRight *= len;
+    zRight *= len;
+
+    /* Up = Look x Right */
+
+    xUp = yLook * zRight - zLook * yRight;
+    yUp = zLook * xRight - xLook * zRight;
+    zUp = xLook * yRight - yLook * xRight;
+    len = 1.0 / sqrtf(xUp * xUp + yUp * yUp + zUp * zUp);
+    xUp *= len;
+    yUp *= len;
+    zUp *= len;
+
+    mf[0][0] = xRight;
+    mf[1][0] = yRight;
+    mf[2][0] = zRight;
+    mf[3][0] = -(xEye * xRight + yEye * yRight + zEye * zRight);
+
+    mf[0][1] = xUp;
+    mf[1][1] = yUp;
+    mf[2][1] = zUp;
+    mf[3][1] = -(xEye * xUp + yEye * yUp + zEye * zUp);
+
+    mf[0][2] = xLook;
+    mf[1][2] = yLook;
+    mf[2][2] = zLook;
+    mf[3][2] = -(xEye * xLook + yEye * yLook + zEye * zLook);
+
+    mf[0][3] = 0;
+    mf[1][3] = 0;
+    mf[2][3] = 0;
+    mf[3][3] = 1;
+}
 
-#if 0
 void guLookAt(Mtx* m, float xEye, float yEye, float zEye, float xAt, float yAt, float zAt, float xUp, float yUp,
               float zUp) {
     Matrix mf;
@@ -14,7 +76,3 @@ void guLookAt(Mtx* m, float xEye, float yEye, float zEye, float xAt, float yAt,
 
     guMtxF2L(mf, m);
 }
-#else
-#pragma GLOBAL_ASM("asm/us/nonmatchings/libultra/gu/lookat/guLookAt.s")
-#endif
-