From a78099f909124966ced36ef0afe72ebe9d4b3270 Mon Sep 17 00:00:00 2001
From: Mr-Wiseguy <68165316+Mr-Wiseguy@users.noreply.github.com>
Date: Fri, 3 Feb 2023 03:50:48 -0500
Subject: [PATCH] Named and documented visibility test functions (func_8011C80C
 and func_8011CFBC) (#932)

more s->w perspective renaming
---
 include/effects_internal.h                    |   4 +-
 include/functions.h                           |   4 +-
 src/325AD0.c                                  |   2 +-
 src/43F0.c                                    |   4 +-
 src/8800.c                                    |  12 +-
 src/a5dd0_len_114e0.c                         | 272 +++++++++++-------
 src/camera.c                                  |  12 +-
 src/cd180_len_38f0.c                          |  12 +-
 src/effects/bulb_glow.c                       |   2 +-
 src/effects/flame.c                           |   6 +-
 src/entity_model.c                            |   8 +-
 src/world/area_flo/flo_10/flo_10_6_waterfx.c  |  50 ++--
 .../dead/area_flo/flo_10/flo_10_6_waterfx.c   |  50 ++--
 ver/us/asm/bss3.s                             |   2 +-
 .../effects/bulb_glow/bulb_glow_appendGfx.s   |   2 +-
 .../motion_blur_flame_appendGfx.s             |   2 +-
 ver/us/effect_shims.yaml                      |   2 +-
 ver/us/symbol_addrs.txt                       |  10 +-
 18 files changed, 266 insertions(+), 190 deletions(-)

diff --git a/include/effects_internal.h b/include/effects_internal.h
index ced7131bb0..ab683af2e2 100644
--- a/include/effects_internal.h
+++ b/include/effects_internal.h
@@ -29,11 +29,11 @@ void shim_guPositionF(float mf[4][4], float r, float p, float h, float s, float
 void shim_guOrthoF(float mf[4][4], float l, float r, float b, float t, float n, float f, float scale);
 void shim_guFrustumF(float mf[4][4], float l, float r, float b, float t, float n, float f, float scale);
 void shim_mem_clear(void* data, s32 numBytes);
-void shim_transform_point(Matrix4f mtx, f32 inX, f32 inY, f32 inZ, f32 inS, f32* outX, f32* outY, f32* outZ, f32* outS);
+void shim_transform_point(Matrix4f mtx, f32 inX, f32 inY, f32 inZ, f32 inS, f32* outX, f32* outY, f32* outZ, f32* outW);
 s32 shim_npc_raycast_down_sides(s32, f32*, f32*, f32*, f32*);
 void shim_sfx_play_sound_at_position(s32 soundID, s32 value2, f32 posX, f32 posY, f32 posZ);
 void shim_mdl_draw_hidden_panel_surface(Gfx**, u16 treeIndex);
-s32 shim_func_8011CFBC(f32, f32, f32, s32, f32*, f32*);
+s32 shim_is_point_visible(f32, f32, f32, s32, f32*, f32*);
 void shim_draw_box(s32 flags, WindowStyle windowStyle, s32 posX, s32 posY, s32 posZ, s32 width, s32 height, u8 opacity,
                    u8 darkening, f32 scaleX, f32 scaleY, f32 rotX, f32 rotY, f32 rotZ, void (*fpDrawContents)(void*),
                    void* drawContentsArg0, Matrix4f rotScaleMtx, s32 translateX, s32 translateY, f32 (*outMtx)[4]);
diff --git a/include/functions.h b/include/functions.h
index 3ebf3e991f..140512d3c6 100644
--- a/include/functions.h
+++ b/include/functions.h
@@ -218,7 +218,7 @@ void set_time_freeze_mode(s32);
 s32 get_map_IDs_by_name(const char* mapName, s16* areaID, s16* mapID);
 
 void get_dpad_input_radial(f32* angle, f32* magnitude);
-void transform_point(Matrix4f mtx, f32 inX, f32 inY, f32 inZ, f32 inS, f32* outX, f32* outY, f32* outZ, f32* outS);
+void transform_point(Matrix4f mtx, f32 inX, f32 inY, f32 inZ, f32 inS, f32* outX, f32* outY, f32* outZ, f32* outW);
 void try_player_footstep_sounds(s32 arg0);
 void phys_update_interact_collider(void);
 void phys_reset_spin_history(void);
@@ -821,7 +821,7 @@ void* load_asset_by_name(const char* assetName, u32* decompressedSize);
 Gfx* mdl_get_copied_gfx(s32 copyIndex);
 void mdl_get_copied_vertices(s32 copyIndex, Vtx** firstVertex, Vtx** copiedVertices, s32* numCopied);
 void mdl_draw_hidden_panel_surface(Gfx** arg0, u16 treeIndex);
-s32 func_8011CFBC(f32 arg0, f32 arg1, f32 arg2, s32 arg3, f32* arg4, f32* arg5);
+s32 is_point_visible(f32 x, f32 y, f32 z, s32 depthQueryID, f32* screenX, f32* screenY);
 void set_screen_overlay_center_worldpos(s32 idx, s32 posIdx, s32 x, s32 y, s32 z);
 void* mdl_get_next_texture_address(s32);
 s32 cancel_current_message(void);
diff --git a/src/325AD0.c b/src/325AD0.c
index 309f5e89d4..3062a808a1 100644
--- a/src/325AD0.c
+++ b/src/325AD0.c
@@ -7,7 +7,7 @@ u32 D_E0200690 = 0x1E6D3457;
 void* effectFuncs[] = {
     guRotateF, guTranslateF, guTranslate, guScaleF, guMtxCatF, guMtxF2L, guMtxL2F, queue_render_task,
     create_effect_instance, remove_effect, general_heap_malloc, mem_clear, NULL, rand_int, clamp_angle, sin_deg,
-    cos_deg, atan2, npc_raycast_down_sides, load_effect, sqrtf, mdl_draw_hidden_panel_surface, func_8011CFBC,
+    cos_deg, atan2, npc_raycast_down_sides, load_effect, sqrtf, mdl_draw_hidden_panel_surface, is_point_visible,
     guPerspectiveF, guMtxIdentF, transform_point, guLookAtHiliteF, set_screen_overlay_params_back,
     set_screen_overlay_center, set_screen_overlay_center_worldpos, mdl_get_next_texture_address, guPositionF, guOrthoF,
     guFrustumF, func_80138D88, draw_box, draw_msg, get_msg_width, get_background_color_blend, sfx_play_sound_at_position
diff --git a/src/43F0.c b/src/43F0.c
index da5e18e28f..fafb819c86 100644
--- a/src/43F0.c
+++ b/src/43F0.c
@@ -424,11 +424,11 @@ void mem_clear(void* data, s32 numBytes) {
     }
 }
 
-void transform_point(Matrix4f mtx, f32 inX, f32 inY, f32 inZ, f32 inS, f32* outX, f32* outY, f32* outZ, f32* outS) {
+void transform_point(Matrix4f mtx, f32 inX, f32 inY, f32 inZ, f32 inS, f32* outX, f32* outY, f32* outZ, f32* outW) {
     *outX = (mtx[0][0] * inX) + (mtx[1][0] * inY) + (mtx[2][0] * inZ) + mtx[3][0];
     *outY = (mtx[0][1] * inX) + (mtx[1][1] * inY) + (mtx[2][1] * inZ) + mtx[3][1];
     *outZ = (mtx[0][2] * inX) + (mtx[1][2] * inY) + (mtx[2][2] * inZ) + mtx[3][2];
-    *outS = (mtx[0][3] * inX) + (mtx[1][3] * inY) + (mtx[2][3] * inZ) + mtx[3][3];
+    *outW = (mtx[0][3] * inX) + (mtx[1][3] * inY) + (mtx[2][3] * inZ) + mtx[3][3];
 }
 
 void copy_matrix(Matrix4f src, Matrix4f dest) {
diff --git a/src/8800.c b/src/8800.c
index 63be0ae59c..f9db462eec 100644
--- a/src/8800.c
+++ b/src/8800.c
@@ -442,12 +442,12 @@ void get_cam_viewport(s32 camID, u16* x, u16* y, u16* width, u16* height) {
 
 void get_screen_coords(s32 camID, f32 x, f32 y, f32 z, s32* screenX, s32* screenY, s32* screenZ) {
     Camera* camera = &gCameras[camID];
-    f32 tS;
+    f32 tW;
     f32 tZ;
     f32 tY;
     f32 tX;
 
-    transform_point(camera->perspectiveMatrix, x, y, z, 1.0f, &tX, &tY, &tZ, &tS);
+    transform_point(camera->perspectiveMatrix, x, y, z, 1.0f, &tX, &tY, &tZ, &tW);
 
     *screenZ = tZ + 5000.0f;
     if (*screenZ < 0) {
@@ -456,14 +456,14 @@ void get_screen_coords(s32 camID, f32 x, f32 y, f32 z, s32* screenX, s32* screen
         *screenZ = 10000;
     }
 
-    if (tS < 0.01 && tS > -0.01) {
+    if (tW < 0.01 && tW > -0.01) {
         *screenX = 0;
         *screenY = 0;
         *screenZ = 0;
     } else {
-        tS = 1.0f / tS;
-        *screenX = (s32) ((camera->viewportW / 2) + (tX * tS * camera->viewportW * 0.5f)) + camera->viewportStartX;
-        *screenY = (s32) ((camera->viewportH / 2) - (tY * tS * camera->viewportH * 0.5f)) + camera->viewportStartY;
+        tW = 1.0f / tW;
+        *screenX = (s32) ((camera->viewportW / 2) + (tX * tW * camera->viewportW * 0.5f)) + camera->viewportStartX;
+        *screenY = (s32) ((camera->viewportH / 2) - (tY * tW * camera->viewportH * 0.5f)) + camera->viewportStartY;
     }
 }
 
diff --git a/src/a5dd0_len_114e0.c b/src/a5dd0_len_114e0.c
index b7531ac50b..aa004b3d8a 100644
--- a/src/a5dd0_len_114e0.c
+++ b/src/a5dd0_len_114e0.c
@@ -29,11 +29,6 @@ typedef struct Fog {
     /* 0x18 */ s32 endDistance;
 } Fog; // size = 0x1C
 
-typedef struct Struct_8011CFBC {
-    /* 0x00 */ s32 unk_00;
-    /* 0x04 */ s32 unk_04;
-} Struct_8011CFBC; // size = 0x08
-
 extern s32 D_801516FC;
 
 extern Gfx D_8014B7F8[];
@@ -447,7 +442,28 @@ Matrix4s mdl_RDPIdentity = {
     }
 };
 
-Struct_8011CFBC D_8014B7A8[] = {
+// The depth buffer contains values encoded in a custom 18-bit floating-point format.
+// There are 3 bits of exponent, 11 bits of mantissa, and 4 bits of "dz".
+// However, two of the "dz" bits are inaccessible to the CPU because it can only access 8 of the 9
+//   bits of each RDRAM byte (the N64 has 9-bit RAM).
+// Therefore, the CPU sees it as a 16-bit value.
+
+// Fields in floating point depth buffer format
+#define DEPTH_EXPONENT_MASK 0xE000
+#define DEPTH_MANTISSA_MASK 0x1FFC
+#define DEPTH_DZ_MASK       0x0003
+
+#define DEPTH_EXPONENT_SHIFT 13
+#define DEPTH_MANTISSA_SHIFT 2
+#define DEPTH_DZ_SHIFT       0
+
+// Lookup table for converting depth buffer values to a 15.3 fixed-point format.
+typedef struct DepthFloatFactors {
+    /* 0x00 */ s32 shift;
+    /* 0x04 */ s32 bias;
+} DepthFloatFactors;
+
+DepthFloatFactors depthFloatLookupTable[] = {
     { 6, 0x00000 },
     { 5, 0x20000 },
     { 4, 0x30000 },
@@ -459,6 +475,11 @@ Struct_8011CFBC D_8014B7A8[] = {
     { 0, 0x00000 },
 };
 
+// Maximum depth value after the viewport transform.
+// The multiplication by 2 comes from transforming depth from (-0.5, 0.5) to (0.0, 1.0).
+// The multiplication by 32 comes from scaling the RSP does to increase depth precision.
+#define MAX_VIEWPORT_DEPTH (2 * 32 * ((G_MAXZ / 2)))
+
 s32 D_8014B7F0 = 0;
 
 // padding?
@@ -1098,7 +1119,7 @@ extern RenderTask mdl_clearRenderTasks[3][0x100];
 
 extern s32 D_801A7000; // todo ???
 
-extern u16 D_80153380[16];
+extern u16 depthCopyBuffer[16];
 
 void update_shadows(void);
 s32 step_entity_commandlist(Entity* entity);
@@ -4286,7 +4307,7 @@ void func_80116698(void) {
 void render_models(void) {
     RenderTask rt;
     RenderTask* rtPtr = &rt;
-    f32 outX, outY, outZ, outS;
+    f32 outX, outY, outZ, outW;
     f32 m00, m01, m02, m03;
     f32 m10, m11, m12, m13;
     f32 m20, m21, m22, m23;
@@ -4308,14 +4329,15 @@ void render_models(void) {
     outX = (m00 * xComp) + (m10 * yComp) + (m20 * zComp) + m30; \
     outY = (m01 * xComp) + (m11 * yComp) + (m21 * zComp) + m31; \
     outZ = (m02 * xComp) + (m12 * yComp) + (m22 * zComp) + m32; \
-    outS = (m03 * xComp) + (m13 * yComp) + (m23 * zComp) + m33; \
-    if (outS == 0.0f) { \
+    outW = (m03 * xComp) + (m13 * yComp) + (m23 * zComp) + m33; \
+    if (outW == 0.0f) { \
         break; \
     } \
-    outS = 1.0f / outS; \
-    xComp = outX * outS; \
-    yComp = outY * outS; \
-    zComp = outZ * outS; \
+    /* Perspective divide */ \
+    outW = 1.0f / outW; \
+    xComp = outX * outW; \
+    yComp = outY * outW; \
+    zComp = outZ * outW; \
     if (zComp > -1.0f && xComp >= -1.0f && xComp <= 1.0f && yComp >= -1.0f && yComp <= 1.0f) { \
         break; \
     }
@@ -4433,7 +4455,7 @@ void render_models(void) {
             }
         }
 
-        transform_point(camera->perspectiveMatrix, x, y, z, 1.0f, &outX, &outY, &outZ, &outS);
+        transform_point(camera->perspectiveMatrix, x, y, z, 1.0f, &outX, &outY, &outZ, &outW);
         distance = outZ + 5000.0f;
         if (distance < 0) {
             distance = 0;
@@ -4472,13 +4494,13 @@ void render_models(void) {
         transform_point(
             camera->perspectiveMatrix,
             xComp, yComp, zComp, 1.0f,
-            &outX, &outY, &outZ, &outS
+            &outX, &outY, &outZ, &outW
         );
-        if (outS == 0.0f) {
-            outS = 1.0f;
+        if (outW == 0.0f) {
+            outW = 1.0f;
         }
 
-        distance = ((outZ / outS) * 10000.0f);
+        distance = ((outZ / outW) * 10000.0f);
 
         if (!(transformGroup->flags & 2)) {
             rtPtr->appendGfx = render_transform_group;
@@ -5818,42 +5840,57 @@ void mdl_project_tex_coords(s32 modelID, Gfx* destGfx, f32 (*destMtx)[4], void*
 INCLUDE_ASM(s32, "a5dd0_len_114e0", mdl_project_tex_coords);
 #endif
 
-s32 func_8011C80C(u16 arg0, s32 arg3, f32* arg4, f32* arg5) {
+// Checks if the center of a model is visible.
+// If `depthQueryID` is nonnegative, the depth buffer is checked to see if the model's center is occluded by geometry.
+//   Otherwise, the occlusion check is skipped.
+// `depthQueryID` must be between 0 and the size of `depthCopyBuffer` minus 1.
+// Every nonnegative value of `depthQueryID` must be unique within a frame, otherwise the result will corrupt the data
+//   of the previous query that shared the same ID.
+// Occlusion visibility checks are always one frame out of date, as they reference the previous frame's depth buffer.
+s32 is_model_center_visible(u16 modelID, s32 depthQueryID, f32* screenX, f32* screenY) {
     Camera* camera = &gCameras[gCurrentCameraID];
-    Model* model = get_model_from_list_index(get_model_list_index_from_tree_index(arg0));
+    Model* model = get_model_from_list_index(get_model_list_index_from_tree_index(modelID));
     f32 outX;
     f32 outY;
     f32 outZ;
-    f32 outS;
+    f32 outW;
 
-    s32 temp1;
-    s32 temp2;
-    u32 temp3, temp4;
-    u32 temp6;
-    s32 temp5;
-    Struct_8011CFBC* v1;
+    s32 depthExponent;
+    s32 depthMantissa;
+    u32 shiftedMantissa, mantissaBias;
+    u32 decodedDepth;
+    s32 scaledDepth;
 
-    if (arg3 >= 16) {
+    // If an invalid depth query id was provided, return false.
+    if (depthQueryID >= ARRAY_COUNT(depthCopyBuffer)) {
         return FALSE;
     }
-    transform_point(camera->perspectiveMatrix, model->center.x, model->center.y, model->center.z, 1.0f, &outX, &outY, &outZ, &outS);
-    if (outS == 0.0f) {
-        *arg4 = 0.0f;
-        *arg5 = 0.0f;
+    // Transform the model's center into clip space.
+    transform_point(camera->perspectiveMatrix, model->center.x, model->center.y, model->center.z, 1.0f, &outX, &outY, &outZ, &outW);
+    if (outW == 0.0f) {
+        *screenX = 0.0f;
+        *screenY = 0.0f;
         return TRUE;
     }
-    outS = 1.0f / outS;
-    outX *= outS;
-    outY *= -outS;
-    outZ *= outS;
+    // Perform the perspective divide (divide xyz by w) to convert to normalized device coords.
+    // Normalized device coords have a range of (-1, 1) on each axis.
+    outW = 1.0f / outW;
+    outX *= outW;
+    outY *= -outW;
+    outZ *= outW;
+    // Perform the viewport transform for x and y (convert normalized device coords to viewport coords).
+    // Viewport coords have a range of (0, Width) for x and (0, Height) for y.
     outX = (outX * camera->viewportW + camera->viewportW) * 0.5;
     outX += camera->viewportStartX;
     outY = (outY * camera->viewportH + camera->viewportH) * 0.5;
     outY += camera->viewportStartY;
+    // Convert depth from (-1, 1) to (0, 1).
     outZ = (outZ + 1.0f) * 0.5;
-    *arg4 = (s32)outX;
-    *arg5 = (s32)outY;
-    if (arg3 < 0) {
+    // Write out the calculated x and y values.
+    *screenX = (s32)outX;
+    *screenY = (s32)outY;
+    // If a depth query wasn't requested, simply check if the point is within the view frustum.
+    if (depthQueryID < 0) {
         if (outZ > 0.0f) {
             return FALSE;
         } else {
@@ -5862,119 +5899,158 @@ s32 func_8011C80C(u16 arg0, s32 arg3, f32* arg4, f32* arg5) {
     }
     if (outX >= 0.0f && outY >= 0.0f && outX < 320.0f && outY < 240.0f) {
         gDPPipeSync(gMasterGfxPos++);
-        gDPSetTextureImage(gMasterGfxPos++, G_IM_FMT_RGBA, G_IM_SIZ_16b, 320, osVirtualToPhysical(&nuGfxZBuffer[(s32) outY * 320]));
-        gDPSetTile(gMasterGfxPos++, G_IM_FMT_RGBA, G_IM_SIZ_16b, 1, 0x0000, G_TX_LOADTILE, 0, G_TX_NOMIRROR | G_TX_WRAP, G_TX_NOMASK, G_TX_NOLOD, G_TX_NOMIRROR | G_TX_WRAP, 9, G_TX_NOLOD);
-        gDPLoadSync(gMasterGfxPos++);
-        gDPLoadTile(gMasterGfxPos++, G_TX_LOADTILE, (s32) outX * 4, 0, ((s32) outX + 3) * 4, 0);
+        // Load a 4x1 pixel tile of the depth buffer 
+        gDPLoadTextureTile(gMasterGfxPos++, osVirtualToPhysical(&nuGfxZBuffer[(s32) outY * 320]), G_IM_FMT_RGBA, G_IM_SIZ_16b, 320, 1, 
+            (s32) outX, 0, (s32) outX + 3, 0,
+            0,
+            G_TX_NOMIRROR | G_TX_WRAP, G_TX_NOMIRROR | G_TX_WRAP,
+            9, G_TX_NOMASK,
+            G_TX_NOLOD, G_TX_NOLOD);
         gDPPipeSync(gMasterGfxPos++);
-        gDPSetTile(gMasterGfxPos++, G_IM_FMT_RGBA, G_IM_SIZ_16b, 1, 0x0000, G_TX_RENDERTILE, 0, G_TX_NOMIRROR | G_TX_WRAP, G_TX_NOMASK, G_TX_NOLOD, G_TX_NOMIRROR | G_TX_WRAP, 9, G_TX_NOLOD);
-        gDPSetTileSize(gMasterGfxPos++, G_TX_RENDERTILE, (s32) outX * 4, 0, ((s32) outX + 3) * 4, 0);
-        gDPPipeSync(gMasterGfxPos++);
-        gDPSetColorImage(gMasterGfxPos++, G_IM_FMT_RGBA, G_IM_SIZ_16b, 320, D_80153380);
+        // Set the current color image to the buffer where copied depth values are stored.
+        gDPSetColorImage(gMasterGfxPos++, G_IM_FMT_RGBA, G_IM_SIZ_16b, 320, depthCopyBuffer);
         gDPPipeSync(gMasterGfxPos++);
+        // Set up 1 cycle mode and all other relevant othermode params.
+        // One cycle mode must be used here because only one pixel is copied, and copy mode only supports multiples of 4 pixels.
         gDPSetCycleType(gMasterGfxPos++, G_CYC_1CYCLE);
         gDPSetRenderMode(gMasterGfxPos++, G_RM_OPA_SURF, G_RM_OPA_SURF2);
         gDPSetCombineMode(gMasterGfxPos++, G_CC_DECALRGBA, G_CC_DECALRGBA);
         gDPSetTextureFilter(gMasterGfxPos++, G_TF_POINT);
         gDPSetTexturePersp(gMasterGfxPos++, G_TP_NONE);
-        gSPTexture(gMasterGfxPos++, -1, -1, 0, G_TX_RENDERTILE, G_ON);
+        gSPTexture(gMasterGfxPos++, 0xFFFF, 0xFFFF, 0, G_TX_RENDERTILE, G_ON);
         gDPSetTextureLUT(gMasterGfxPos++, G_TT_NONE);
         gDPSetTextureDetail(gMasterGfxPos++, G_TD_CLAMP);
         gDPSetTextureLOD(gMasterGfxPos++, G_TL_TILE);
-        gDPSetScissor(gMasterGfxPos++, G_SC_NON_INTERLACE, arg3, 0, arg3 + 1, 1);
-        gSPTextureRectangle(gMasterGfxPos++, arg3 * 4, 0 * 4, 4 * 4, 1 * 4, G_TX_RENDERTILE, (s32) outX * 32, 0, 0x0400, 0x0400);
+        // Adjust the scissor to only draw to the specified pixel.
+        gDPSetScissor(gMasterGfxPos++, G_SC_NON_INTERLACE, depthQueryID, 0, depthQueryID + 1, 1);
+        // Draw a texrect to copy one pixel of the loaded depth tile to the output buffer.
+        gSPTextureRectangle(gMasterGfxPos++, depthQueryID << 2, 0 << 2, 4 << 2, 1 << 2, G_TX_RENDERTILE, (s32) outX << 5, 0, 1 << 10, 1 << 10);
+        // Sync and swap the color image back to the current framebuffer.
         gDPPipeSync(gMasterGfxPos++);
         gDPSetColorImage(gMasterGfxPos++, G_IM_FMT_RGBA, G_IM_SIZ_16b, 320, osVirtualToPhysical(nuGfxCfb_ptr));
         gDPPipeSync(gMasterGfxPos++);
+        // Reconfigure the frame's normal scissor.
         gDPSetScissor(gMasterGfxPos++, G_SC_NON_INTERLACE, camera->viewportStartX, camera->viewportStartY, camera->viewportStartX + camera->viewportW, camera->viewportStartY + camera->viewportH);
 
-        temp1 = D_80153380[arg3] >> 13;
-        temp2 = (D_80153380[arg3] & 0x1FFF) / 4;
-        v1 = &D_8014B7A8[temp1];
-        temp3 = temp2 << v1->unk_00;
-        temp4 = v1->unk_04;
-        temp6 = (temp3 + temp4) / 8;
-        temp5 = outZ * 32704.0f;
-        if (temp6 < temp5) {
+        // The following code will use last frame's depth value, since the copy that was just written won't be executed until the current frame is drawn.
+
+        // Extract the exponent and mantissa from the depth buffer value.
+        depthExponent = depthCopyBuffer[depthQueryID] >> DEPTH_EXPONENT_SHIFT;
+        depthMantissa = (depthCopyBuffer[depthQueryID] & (DEPTH_MANTISSA_MASK | DEPTH_DZ_MASK)) >> DEPTH_MANTISSA_SHIFT;
+        // Convert the exponent and mantissa into a fixed-point value.
+        shiftedMantissa = depthMantissa << depthFloatLookupTable[depthExponent].shift;
+        mantissaBias = depthFloatLookupTable[depthExponent].bias;
+        // Remove the 3 fractional bits of precision.
+        decodedDepth = (shiftedMantissa + mantissaBias) >> 3;
+        // Convert the calculated screen depth into viewport depth.
+        scaledDepth = outZ * MAX_VIEWPORT_DEPTH;
+        if (decodedDepth < scaledDepth) {
             return FALSE;
         }
     }
     return outZ > 0.0f;
 }
 
-s32 func_8011CFBC(f32 x, f32 y, f32 z, s32 arg3, f32* arg4, f32* arg5) {
+// Checks if a point is visible on screen.
+// If `depthQueryID` is nonnegative, the depth buffer is checked to see if the point is occluded by geometry.
+//   Otherwise, the occlusion check is skipped.
+// `depthQueryID` must be between 0 and the size of `depthCopyBuffer` minus 1.
+// Every nonnegative value of `depthQueryID` must be unique within a frame, otherwise the result will corrupt the data
+//   of the previous query that shared the same ID.
+// Occlusion visibility checks are always one frame out of date, as they reference the previous frame's depth buffer.
+s32 is_point_visible(f32 x, f32 y, f32 z, s32 depthQueryID, f32* screenX, f32* screenY) {
     Camera* camera = &gCameras[gCurrentCameraID];
     f32 outX;
     f32 outY;
     f32 outZ;
-    f32 outS;
+    f32 outW;
 
-    s32 temp1;
-    s32 temp2;
-    u32 temp3, temp4;
-    u32 temp6;
-    s32 temp5;
-    Struct_8011CFBC* v1;
+    s32 depthExponent;
+    s32 depthMantissa;
+    u32 shiftedMantissa, mantissaBias;
+    u32 decodedDepth;
+    s32 scaledDepth;
 
-    if (arg3 >= 16) {
+    // If an invalid depth query id was provided, return false.
+    if (depthQueryID >= ARRAY_COUNT(depthCopyBuffer)) {
         return FALSE;
     }
-    transform_point(camera->perspectiveMatrix, x, y, z, 1.0f, &outX, &outY, &outZ, &outS);
-    if (outS == 0.0f) {
-        *arg4 = 0.0f;
-        *arg5 = 0.0f;
+    // Transform the point into clip space.
+    transform_point(camera->perspectiveMatrix, x, y, z, 1.0f, &outX, &outY, &outZ, &outW);
+    if (outW == 0.0f) {
+        *screenX = 0.0f;
+        *screenY = 0.0f;
         return TRUE;
     }
-    outS = 1.0f / outS;
-    outX *= outS;
-    outY *= -outS;
-    outZ *= outS;
+    // Perform the perspective divide (divide xyz by w) to convert to normalized device coords.
+    // Normalized device coords have a range of (-1, 1) on each axis.
+    outW = 1.0f / outW;
+    outX *= outW;
+    outY *= -outW;
+    outZ *= outW;
+    // Perform the viewport transform for x and y (convert normalized device coords to viewport coords).
+    // Viewport coords have a range of (0, Width) for x and (0, Height) for y.
     outX = (outX * camera->viewportW + camera->viewportW) * 0.5;
     outX += camera->viewportStartX;
     outY = (outY * camera->viewportH + camera->viewportH) * 0.5;
     outY += camera->viewportStartY;
+    // Convert depth from (-1, 1) to (0, 1).
     outZ = (outZ + 1.0f) * 0.5;
-    *arg4 = outX;
-    *arg5 = outY;
-    if (arg3 < 0) {
+    // Write out the calculated x and y values.
+    *screenX = outX;
+    *screenY = outY;
+    // If a depth query wasn't requested, simply check if the point is within the view frustum.
+    if (depthQueryID < 0) {
         return outZ > 0.0f;
     }
     if (outX >= 0.0f && outY >= 0.0f && outX < 320.0f && outY < 240.0f) {
         gDPPipeSync(gMasterGfxPos++);
-        gDPSetTextureImage(gMasterGfxPos++, G_IM_FMT_RGBA, G_IM_SIZ_16b, 320, osVirtualToPhysical(&nuGfxZBuffer[(s32) outY * 320]));
-        gDPSetTile(gMasterGfxPos++, G_IM_FMT_RGBA, G_IM_SIZ_16b, 1, 0x0000, G_TX_LOADTILE, 0, G_TX_NOMIRROR | G_TX_WRAP, G_TX_NOMASK, G_TX_NOLOD, G_TX_NOMIRROR | G_TX_WRAP, 9, G_TX_NOLOD);
-        gDPLoadSync(gMasterGfxPos++);
-        gDPLoadTile(gMasterGfxPos++, G_TX_LOADTILE, (s32) outX * 4, 0, ((s32) outX + 3) * 4, 0);
+        // Load a 4x1 pixel tile of the depth buffer 
+        gDPLoadTextureTile(gMasterGfxPos++, osVirtualToPhysical(&nuGfxZBuffer[(s32) outY * 320]), G_IM_FMT_RGBA, G_IM_SIZ_16b, 320, 1, 
+            (s32) outX, 0, (s32) outX + 3, 0,
+            0,
+            G_TX_NOMIRROR | G_TX_WRAP, G_TX_NOMIRROR | G_TX_WRAP,
+            9, G_TX_NOMASK,
+            G_TX_NOLOD, G_TX_NOLOD);
         gDPPipeSync(gMasterGfxPos++);
-        gDPSetTile(gMasterGfxPos++, G_IM_FMT_RGBA, G_IM_SIZ_16b, 1, 0x0000, G_TX_RENDERTILE, 0, G_TX_NOMIRROR | G_TX_WRAP, G_TX_NOMASK, G_TX_NOLOD, G_TX_NOMIRROR | G_TX_WRAP, 9, G_TX_NOLOD);
-        gDPSetTileSize(gMasterGfxPos++, G_TX_RENDERTILE, (s32) outX * 4, 0, ((s32) outX + 3) * 4, 0);
-        gDPPipeSync(gMasterGfxPos++);
-        gDPSetColorImage(gMasterGfxPos++, G_IM_FMT_RGBA, G_IM_SIZ_16b, 320, D_80153380);
+        // Set the current color image to the buffer where copied depth values are stored.
+        gDPSetColorImage(gMasterGfxPos++, G_IM_FMT_RGBA, G_IM_SIZ_16b, 320, depthCopyBuffer);
         gDPPipeSync(gMasterGfxPos++);
+        // Set up 1 cycle mode and all other relevant othermode params.
+        // One cycle mode must be used here because only one pixel is copied, and copy mode only supports multiples of 4 pixels.
         gDPSetCycleType(gMasterGfxPos++, G_CYC_1CYCLE);
         gDPSetRenderMode(gMasterGfxPos++, G_RM_OPA_SURF, G_RM_OPA_SURF2);
         gDPSetCombineMode(gMasterGfxPos++, G_CC_DECALRGBA, G_CC_DECALRGBA);
         gDPSetTextureFilter(gMasterGfxPos++, G_TF_POINT);
         gDPSetTexturePersp(gMasterGfxPos++, G_TP_NONE);
-        gSPTexture(gMasterGfxPos++, -1, -1, 0, G_TX_RENDERTILE, G_ON);
+        gSPTexture(gMasterGfxPos++, 0xFFFF, 0xFFFF, 0, G_TX_RENDERTILE, G_ON);
         gDPSetTextureLUT(gMasterGfxPos++, G_TT_NONE);
         gDPSetTextureDetail(gMasterGfxPos++, G_TD_CLAMP);
         gDPSetTextureLOD(gMasterGfxPos++, G_TL_TILE);
-        gDPSetScissor(gMasterGfxPos++, G_SC_NON_INTERLACE, arg3, 0, arg3 + 1, 1);
-        gSPTextureRectangle(gMasterGfxPos++, arg3 * 4, 0 * 4, (arg3 + 1) * 4, 1 * 4, G_TX_RENDERTILE, (s32) outX * 32, 0, 0x0400, 0x0400);
+        // Adjust the scissor to only draw to the specified pixel.
+        gDPSetScissor(gMasterGfxPos++, G_SC_NON_INTERLACE, depthQueryID, 0, depthQueryID + 1, 1);
+        // Draw a texrect to copy one pixel of the loaded depth tile to the output buffer.
+        gSPTextureRectangle(gMasterGfxPos++, depthQueryID << 2, 0 << 2, (depthQueryID + 1) << 2, 1 << 2, G_TX_RENDERTILE, (s32) outX << 5, 0, 1 << 10, 1 << 10);
+        // Sync and swap the color image back to the current framebuffer.
         gDPPipeSync(gMasterGfxPos++);
         gDPSetColorImage(gMasterGfxPos++, G_IM_FMT_RGBA, G_IM_SIZ_16b, 320, osVirtualToPhysical(nuGfxCfb_ptr));
         gDPPipeSync(gMasterGfxPos++);
+        // Reconfigure the frame's normal scissor.
         gDPSetScissor(gMasterGfxPos++, G_SC_NON_INTERLACE, camera->viewportStartX, camera->viewportStartY, camera->viewportStartX + camera->viewportW, camera->viewportStartY + camera->viewportH);
 
-        temp1 = D_80153380[arg3] >> 13;
-        temp2 = (D_80153380[arg3] & 0x1FFF) / 4;
-        v1 = &D_8014B7A8[temp1];
-        temp3 = temp2 << v1->unk_00;
-        temp4 = v1->unk_04;
-        temp6 = (temp3 + temp4) / 8;
-        temp5 = outZ * 32704.0f;
-        if (temp6 < temp5) {
+        // The following code will use last frame's depth value, since the copy that was just written won't be executed until the current frame is drawn.
+
+        // Extract the exponent and mantissa from the depth buffer value.
+        depthExponent = depthCopyBuffer[depthQueryID] >> DEPTH_EXPONENT_SHIFT;
+        depthMantissa = (depthCopyBuffer[depthQueryID] & (DEPTH_MANTISSA_MASK | DEPTH_DZ_MASK)) >> DEPTH_MANTISSA_SHIFT;
+        // Convert the exponent and mantissa into a fixed-point value.
+        shiftedMantissa = depthMantissa << depthFloatLookupTable[depthExponent].shift;
+        mantissaBias = depthFloatLookupTable[depthExponent].bias;
+        // Remove the 3 fractional bits of precision.
+        decodedDepth = (shiftedMantissa + mantissaBias) >> 3;
+        // Convert the calculated screen depth into viewport depth.
+        scaledDepth = outZ * MAX_VIEWPORT_DEPTH;
+        if (decodedDepth < scaledDepth) {
             return FALSE;
         }
     }
diff --git a/src/camera.c b/src/camera.c
index e409b8f300..b4cc4c5182 100644
--- a/src/camera.c
+++ b/src/camera.c
@@ -165,7 +165,7 @@ void func_80032C64(Camera* camera) {
     CameraControlSettings* settings2;
     CameraControlSettings* settings3;
     s32 s2;
-    f32 X, Y, Z, S;
+    f32 X, Y, Z, W;
     f32 product;
     f32 newPosX, newPosZ;
     Collider* zone;
@@ -189,12 +189,12 @@ void func_80032C64(Camera* camera) {
                                (f32)camera->viewportW / (f32)camera->viewportH, camera->nearClip, camera->farClip, 1.0f);
                 guMtxCatF(camera->viewMtxPlayer, camera->perspectiveMatrix, camera->perspectiveMatrix);
                 transform_point(camera->perspectiveMatrix, camera->targetPos.x, camera->targetPos.y, camera->targetPos.z,
-                                1.0f, &X, &Y, &Z, &S);
-                if (S == 0.0f) {
-                    S = 1.0f;
+                                1.0f, &X, &Y, &Z, &W);
+                if (W == 0.0f) {
+                    W = 1.0f;
                 }
-                S = 1.0f / S;
-                X *= S;
+                W = 1.0f / W;
+                X *= W;
                 camera->unk_52C = (X > 0.0f) ? 1 : (X < 0.0f) ? -1 : 0;
                 camera->unk_530 = 0;
             } else {
diff --git a/src/cd180_len_38f0.c b/src/cd180_len_38f0.c
index a9f963f3a9..b2acf3b595 100644
--- a/src/cd180_len_38f0.c
+++ b/src/cd180_len_38f0.c
@@ -412,16 +412,16 @@ void set_screen_overlay_center(s32 idx, s32 arg1, s32 arg2, s32 arg3) {
 
 void set_screen_overlay_center_worldpos(s32 idx, s32 posIdx, s32 x, s32 y, s32 z) {
     Camera* camera = &gCameras[gCurrentCameraID];
-    f32 tx, ty, tz, ts;
+    f32 tx, ty, tz, tw;
 
     switch (idx) {
         case 0:
         case 1:
-            transform_point(camera->perspectiveMatrix, x, y, z, 1.0f, &tx, &ty, &tz, &ts);
-            ts = 1.0f / ts;
-            tx *= ts;
-            ty *= -ts;
-            tz *= ts;
+            transform_point(camera->perspectiveMatrix, x, y, z, 1.0f, &tx, &ty, &tz, &tw);
+            tw = 1.0f / tw;
+            tx *= tw;
+            ty *= -tw;
+            tz *= tw;
             tx = (((tx * camera->viewportW) + camera->viewportW) * 0.5) + camera->viewportStartX;
             ty = (((ty * camera->viewportH) + camera->viewportH) * 0.5) + camera->viewportStartY;
 
diff --git a/src/effects/bulb_glow.c b/src/effects/bulb_glow.c
index 41366d3a44..32d27d06dd 100644
--- a/src/effects/bulb_glow.c
+++ b/src/effects/bulb_glow.c
@@ -200,7 +200,7 @@ void bulb_glow_appendGfx(void* effect) {
     temp_s6 = temp_s1->unk_10;
     temp_s3 = temp_s1->unk_14;
 
-    var_v1 = shim_func_8011CFBC(data->pos.x, data->pos.y, data->pos.z, data->unk_1C, &sp18, &sp1C);
+    var_v1 = shim_is_point_visible(data->pos.x, data->pos.y, data->pos.z, data->unk_1C, &sp18, &sp1C);
     if (unk_00 == 5) {
         var_v1 = 1;
     }
diff --git a/src/effects/flame.c b/src/effects/flame.c
index a5d50ed869..e2661c79a9 100644
--- a/src/effects/flame.c
+++ b/src/effects/flame.c
@@ -118,10 +118,10 @@ void flame_render(EffectInstance* effect) {
     f32 outX;
     f32 outY;
     f32 outZ;
-    f32 outS;
+    f32 outW;
 
     shim_transform_point(gCameras[gCurrentCameraID].perspectiveMatrix, data->pos.x, data->pos.y, data->pos.z, 1.0f,
-                         &outX, &outY, &outZ, &outS);
+                         &outX, &outY, &outZ, &outW);
 
     outDist = outZ + 5000;
     if (outDist < 0) {
@@ -130,7 +130,7 @@ void flame_render(EffectInstance* effect) {
         outDist = 10000;
     }
 
-    if (outS < 0.01 && -0.01 < outS) {
+    if (outW < 0.01 && -0.01 < outW) {
         outDist = 0;
     }
 
diff --git a/src/entity_model.c b/src/entity_model.c
index aaad6adb9b..15d1b5a699 100644
--- a/src/entity_model.c
+++ b/src/entity_model.c
@@ -415,7 +415,7 @@ void draw_entity_model_A(s32 modelIdx, Mtx* transformMtx) {
     RenderTask* rtPtr = &rt;
     Camera* camera = &gCameras[gCurrentCamID];
     Matrix4f mtx;
-    f32 x, y, z, s;
+    f32 x, y, z, w;
     f32 inX, inY, inZ;
 
     if ((gGameStatusPtr->isBattle == 0) || (modelIdx & 0x800)) {
@@ -433,7 +433,7 @@ void draw_entity_model_A(s32 modelIdx, Mtx* transformMtx) {
                             inX = mtx[3][0];
                             inY = mtx[3][1];
                             inZ = mtx[3][2];
-                            transform_point(camera->perspectiveMatrix, inX, inY, inZ, 1.0f, &x, &y, &z, &s);
+                            transform_point(camera->perspectiveMatrix, inX, inY, inZ, 1.0f, &x, &y, &z, &w);
                             rtPtr->renderMode = model->renderMode;
                             rtPtr->appendGfxArg = model;
                             rtPtr->appendGfx = (void(*)(void*))appendGfx_entity_model;
@@ -453,7 +453,7 @@ void draw_entity_model_B(s32 modelIdx, Mtx* transformMtx, s32 vertexSegment, Vec
     RenderTask* rtPtr = &rt;
     Camera* camera = &gCameras[gCurrentCamID];
     Matrix4f mtx;
-    f32 x, y, z, s;
+    f32 x, y, z, w;
     f32 inX, inY, inZ;
 
     if ((gGameStatusPtr->isBattle == 0) || (modelIdx & 0x800)) {
@@ -472,7 +472,7 @@ void draw_entity_model_B(s32 modelIdx, Mtx* transformMtx, s32 vertexSegment, Vec
                             inX = mtx[3][0];
                             inY = mtx[3][1];
                             inZ = mtx[3][2];
-                            transform_point(camera->perspectiveMatrix, inX, inY, inZ, 1.0f, &x, &y, &z, &s);
+                            transform_point(camera->perspectiveMatrix, inX, inY, inZ, 1.0f, &x, &y, &z, &w);
                             rtPtr->renderMode = model->renderMode;
                             rtPtr->appendGfxArg = model;
                             rtPtr->appendGfx = (void(*)(void*))appendGfx_entity_model;
diff --git a/src/world/area_flo/flo_10/flo_10_6_waterfx.c b/src/world/area_flo/flo_10/flo_10_6_waterfx.c
index b03269a106..62d8646f0b 100644
--- a/src/world/area_flo/flo_10/flo_10_6_waterfx.c
+++ b/src/world/area_flo/flo_10/flo_10_6_waterfx.c
@@ -101,7 +101,7 @@ void N(UnkModelFunc001)(void) {
     ModelBoundingBox* bb = (ModelBoundingBox*) model->modelNode->propertyList;
     f32 bbHalfX = bb->halfSizeX;
     f32 bbHalfZ = bb->halfSizeZ;
-    f32 outX, outY, outZ, outS;
+    f32 outX, outY, outZ, outW;
     f32 temp_f24;
     f32 temp_f26;
     f32 temp_f20;
@@ -109,14 +109,14 @@ void N(UnkModelFunc001)(void) {
 
     transform_point(camera->perspectiveMatrix,
                     model->center.x - bbHalfX, model->center.y, model->center.z - bbHalfZ, 1.0f,
-                    &outX, &outY, &outZ, &outS);
+                    &outX, &outY, &outZ, &outW);
 
-    outX *= 1.0f / outS;
-    outY *= -(1.0f / outS);
-    outZ *= 1.0f / outS;
-    outS = 1.0f / outS;
+    outX *= 1.0f / outW;
+    outY *= -(1.0f / outW);
+    outZ *= 1.0f / outW;
+    outW = 1.0f / outW;
 
-    if (outS < 0.0f) {
+    if (outW < 0.0f) {
         outX = 0.0f;
         outY = 1.0f;
     }
@@ -125,16 +125,16 @@ void N(UnkModelFunc001)(void) {
 
     transform_point(camera->perspectiveMatrix,
                     model->center.x - bbHalfX, model->center.y, model->center.z + bbHalfZ, 1.0f,
-                    &outX, &outY, &outZ, &outS);
+                    &outX, &outY, &outZ, &outW);
 
-    outX *= 1.0f / outS;
-    outY *= -(1.0f / outS);
-    outZ *= 1.0f / outS;
-    outS = 1.0f / outS;
+    outX *= 1.0f / outW;
+    outY *= -(1.0f / outW);
+    outZ *= 1.0f / outW;
+    outW = 1.0f / outW;
 
     temp_f24 = temp_f20;
     temp_f26 = temp_f22;
-    if (outS < 0.0f) {
+    if (outW < 0.0f) {
         outX = 0.0f;
         outY = 1.0f;
     }
@@ -157,14 +157,14 @@ void N(UnkModelFunc001)(void) {
 
     transform_point(camera->perspectiveMatrix,
                     model->center.x + bbHalfX, model->center.y, model->center.z + bbHalfZ, 1.0f,
-                    &outX, &outY, &outZ, &outS);
+                    &outX, &outY, &outZ, &outW);
 
-    outX *= 1.0f / outS;
-    outY *= -(1.0f / outS);
-    outZ *= 1.0f / outS;
-    outS = 1.0f / outS;
+    outX *= 1.0f / outW;
+    outY *= -(1.0f / outW);
+    outZ *= 1.0f / outW;
+    outW = 1.0f / outW;
 
-    if (outS < 0.0f) {
+    if (outW < 0.0f) {
         outX = 1.0f;
         outY = 1.0f;
     }
@@ -187,14 +187,14 @@ void N(UnkModelFunc001)(void) {
 
     transform_point(camera->perspectiveMatrix,
                     model->center.x + bbHalfX, model->center.y, model->center.z - bbHalfZ, 1.0f,
-                    &outX, &outY, &outZ, &outS);
+                    &outX, &outY, &outZ, &outW);
 
-    outX *= 1.0f / outS;
-    outY *= -(1.0f / outS);
-    outZ *= 1.0f / outS;
-    outS = 1.0f / outS;
+    outX *= 1.0f / outW;
+    outY *= -(1.0f / outW);
+    outZ *= 1.0f / outW;
+    outW = 1.0f / outW;
 
-    if (outS < 0.0f) {
+    if (outW < 0.0f) {
         outX = 1.0f;
         outY = 1.0f;
     }
diff --git a/src/world/dead/area_flo/flo_10/flo_10_6_waterfx.c b/src/world/dead/area_flo/flo_10/flo_10_6_waterfx.c
index 58fd8875b1..a639805fe9 100644
--- a/src/world/dead/area_flo/flo_10/flo_10_6_waterfx.c
+++ b/src/world/dead/area_flo/flo_10/flo_10_6_waterfx.c
@@ -171,7 +171,7 @@ void N(UnkModelFunc001)(void) {
     ModelBoundingBox* bb = (ModelBoundingBox*) model->modelNode->propertyList;
     f32 bbHalfX = bb->halfSizeX;
     f32 bbHalfZ = bb->halfSizeZ;
-    f32 outX, outY, outZ, outS;
+    f32 outX, outY, outZ, outW;
     Gfx* new_var;
     f32 temp_f24;
     f32 temp_f26;
@@ -180,14 +180,14 @@ void N(UnkModelFunc001)(void) {
 
     transform_point(camera->perspectiveMatrix,
                     model->center.x - bbHalfX, model->center.y, model->center.z - bbHalfZ, 1.0f,
-                    &outX, &outY, &outZ, &outS);
+                    &outX, &outY, &outZ, &outW);
 
-    outX *= 1.0f / outS;
-    outY *= -(1.0f / outS);
-    outZ *= 1.0f / outS;
-    outS = 1.0f / outS;
+    outX *= 1.0f / outW;
+    outY *= -(1.0f / outW);
+    outZ *= 1.0f / outW;
+    outW = 1.0f / outW;
 
-    if (outS < 0.0f) {
+    if (outW < 0.0f) {
         outX = 0.0f;
         outY = 1.0f;
     }
@@ -196,16 +196,16 @@ void N(UnkModelFunc001)(void) {
 
     transform_point(camera->perspectiveMatrix,
                     model->center.x - bbHalfX, model->center.y, model->center.z + bbHalfZ, 1.0f,
-                    &outX, &outY, &outZ, &outS);
+                    &outX, &outY, &outZ, &outW);
 
-    outX *= 1.0f / outS;
-    outY *= -(1.0f / outS);
-    outZ *= 1.0f / outS;
-    outS = 1.0f / outS;
+    outX *= 1.0f / outW;
+    outY *= -(1.0f / outW);
+    outZ *= 1.0f / outW;
+    outW = 1.0f / outW;
 
     temp_f24 = temp_f20;
     temp_f26 = temp_f22;
-    if (outS < 0.0f) {
+    if (outW < 0.0f) {
         outX = 0.0f;
         outY = 1.0f;
     }
@@ -228,14 +228,14 @@ void N(UnkModelFunc001)(void) {
 
     transform_point(camera->perspectiveMatrix,
                     model->center.x + bbHalfX, model->center.y, model->center.z + bbHalfZ, 1.0f,
-                    &outX, &outY, &outZ, &outS);
+                    &outX, &outY, &outZ, &outW);
 
-    outX *= 1.0f / outS;
-    outY *= -(1.0f / outS);
-    outZ *= 1.0f / outS;
-    outS = 1.0f / outS;
+    outX *= 1.0f / outW;
+    outY *= -(1.0f / outW);
+    outZ *= 1.0f / outW;
+    outW = 1.0f / outW;
 
-    if (outS < 0.0f) {
+    if (outW < 0.0f) {
         outX = 1.0f;
         outY = 1.0f;
     }
@@ -258,14 +258,14 @@ void N(UnkModelFunc001)(void) {
 
     transform_point(camera->perspectiveMatrix,
                     model->center.x + bbHalfX, model->center.y, model->center.z - bbHalfZ, 1.0f,
-                    &outX, &outY, &outZ, &outS);
+                    &outX, &outY, &outZ, &outW);
 
-    outX *= 1.0f / outS;
-    outY *= -(1.0f / outS);
-    outZ *= 1.0f / outS;
-    outS = 1.0f / outS;
+    outX *= 1.0f / outW;
+    outY *= -(1.0f / outW);
+    outZ *= 1.0f / outW;
+    outW = 1.0f / outW;
 
-    if (outS < 0.0f) {
+    if (outW < 0.0f) {
         outX = 1.0f;
         outY = 1.0f;
     }
diff --git a/ver/us/asm/bss3.s b/ver/us/asm/bss3.s
index ef9ad9fab1..f28d914a61 100644
--- a/ver/us/asm/bss3.s
+++ b/ver/us/asm/bss3.s
@@ -289,7 +289,7 @@ dlabel D_80153376
 dlabel D_80153378
 .space 8
 
-dlabel D_80153380
+dlabel depthCopyBuffer
 .space 0x00000020
 
 dlabel mdl_renderTaskLists
diff --git a/ver/us/asm/nonmatchings/effects/bulb_glow/bulb_glow_appendGfx.s b/ver/us/asm/nonmatchings/effects/bulb_glow/bulb_glow_appendGfx.s
index cbd90579c7..0d5b43a994 100644
--- a/ver/us/asm/nonmatchings/effects/bulb_glow/bulb_glow_appendGfx.s
+++ b/ver/us/asm/nonmatchings/effects/bulb_glow/bulb_glow_appendGfx.s
@@ -55,7 +55,7 @@ glabel bulb_glow_appendGfx
 /* 37A730 E0078340 8E06000C */  lw        $a2, 0xc($s0)
 /* 37A734 E0078344 8E07001C */  lw        $a3, 0x1c($s0)
 /* 37A738 E0078348 24840008 */  addiu     $a0, $a0, 8
-/* 37A73C E007834C 0C08015C */  jal       shim_func_8011CFBC
+/* 37A73C E007834C 0C08015C */  jal       shim_is_point_visible
 /* 37A740 E0078350 AEA40000 */   sw       $a0, ($s5)
 /* 37A744 E0078354 0040182D */  daddu     $v1, $v0, $zero
 /* 37A748 E0078358 24020005 */  addiu     $v0, $zero, 5
diff --git a/ver/us/asm/nonmatchings/effects/motion_blur_flame/motion_blur_flame_appendGfx.s b/ver/us/asm/nonmatchings/effects/motion_blur_flame/motion_blur_flame_appendGfx.s
index 6a6cffc7e1..0484c240e7 100644
--- a/ver/us/asm/nonmatchings/effects/motion_blur_flame/motion_blur_flame_appendGfx.s
+++ b/ver/us/asm/nonmatchings/effects/motion_blur_flame/motion_blur_flame_appendGfx.s
@@ -70,7 +70,7 @@ glabel motion_blur_flame_appendGfx
 /* 3A2CCC E00A233C 27A2004C */  addiu     $v0, $sp, 0x4c
 /* 3A2CD0 E00A2340 44060000 */  mfc1      $a2, $f0
 /* 3A2CD4 E00A2344 2407FFFF */  addiu     $a3, $zero, -1
-/* 3A2CD8 E00A2348 0C08015C */  jal       shim_func_8011CFBC
+/* 3A2CD8 E00A2348 0C08015C */  jal       shim_is_point_visible
 /* 3A2CDC E00A234C AFA20014 */   sw       $v0, 0x14($sp)
 /* 3A2CE0 E00A2350 080288D9 */  j         .LE00A2364
 /* 3A2CE4 E00A2354 0040302D */   daddu    $a2, $v0, $zero
diff --git a/ver/us/effect_shims.yaml b/ver/us/effect_shims.yaml
index 2fb17c8044..824f1d4327 100644
--- a/ver/us/effect_shims.yaml
+++ b/ver/us/effect_shims.yaml
@@ -20,7 +20,7 @@
 - shim_load_effect
 - shim_sqrtf
 - shim_mdl_draw_hidden_panel_surface
-- shim_func_8011CFBC
+- shim_is_point_visible
 - shim_guPerspectiveF
 - shim_guMtxIdentF
 - shim_transform_point
diff --git a/ver/us/symbol_addrs.txt b/ver/us/symbol_addrs.txt
index 34949c31a0..1418ec0be0 100644
--- a/ver/us/symbol_addrs.txt
+++ b/ver/us/symbol_addrs.txt
@@ -4066,8 +4066,8 @@ mdl_make_local_vertex_copy = 0x8011C164; // type:func rom:0xB2864
 mdl_get_copied_vertices = 0x8011C2B0; // type:func rom:0xB29B0
 mdl_get_copied_gfx = 0x8011C2EC; // type:func rom:0xB29EC
 mdl_project_tex_coords = 0x8011C32C; // type:func rom:0xB2A2C
-func_8011C80C = 0x8011C80C; // type:func rom:0xB2F0C
-func_8011CFBC = 0x8011CFBC; // type:func rom:0xB36BC
+is_model_center_visible = 0x8011C80C; // type:func rom:0xB2F0C
+is_point_visible = 0x8011CFBC; // type:func rom:0xB36BC
 mdl_draw_hidden_panel_surface = 0x8011D72C; // type:func rom:0xB3E2C
 mdl_get_next_texture_address = 0x8011D7E4; // type:func rom:0xB3EE4
 mdl_set_all_fog_mode = 0x8011D82C; // type:func rom:0xB3F2C
@@ -4522,7 +4522,7 @@ gRenderModelEnvB = 0x8014B765; // type:data rom:0xE1E65
 D_8014B766 = 0x8014B766; // type:data rom:0xE1E66
 D_8014B767 = 0x8014B767; // type:data rom:0xE1E67
 mdl_RDPIdentity = 0x8014B768; // type:data rom:0xE1E68
-D_8014B7A8 = 0x8014B7A8; // type:data rom:0xE1EA8
+depthFloatLookupTable = 0x8014B7A8; // type:data rom:0xE1EA8
 D_8014B7F0 = 0x8014B7F0; // type:data rom:0xE1EF0
 D_8014B7F8 = 0x8014B7F8; // type:data rom:0xE1EF8
 D_8014B820 = 0x8014B820; // type:data rom:0xE1F20
@@ -4958,7 +4958,7 @@ D_80153370 = 0x80153370; // type:data rom:0xE9A70
 D_80153374 = 0x80153374; // type:data rom:0xE9A74
 D_80153376 = 0x80153376; // type:data rom:0xE9A76
 D_80153378 = 0x80153378; // type:data rom:0xE9A78
-D_80153380 = 0x80153380; // type:data rom:0xE9A80
+depthCopyBuffer = 0x80153380; // type:data rom:0xE9A80
 mdl_renderTaskLists = 0x801533A0; // type:data rom:0xE9AA0
 mdl_renderTaskQueueIdx = 0x801533AC; // type:data rom:0xE9AAC
 mdl_renderTaskCount = 0x801533B0; // type:data rom:0xE9AB0
@@ -7984,7 +7984,7 @@ shim_npc_raycast_down_sides = 0xE0200530; // type:func rom:0x326000
 shim_load_effect = 0xE0200540; // type:func rom:0x326010
 shim_sqrtf = 0xE0200550; // type:func rom:0x326020
 shim_mdl_draw_hidden_panel_surface = 0xE0200560; // type:func rom:0x326030
-shim_func_8011CFBC = 0xE0200570; // type:func rom:0x326040
+shim_is_point_visible = 0xE0200570; // type:func rom:0x326040
 shim_guPerspectiveF = 0xE0200580; // type:func rom:0x326050
 shim_guMtxIdentF = 0xE0200590; // type:func rom:0x326060
 shim_transform_point = 0xE02005A0; // type:func rom:0x326070