`code_80140E80` OK and preliminary documentation, Fbdemo_Wipe4 OK and documented (#1106)

* OK, start documentation

* More documentation

Co-authored-by: Tharo <17233964+Thar0@users.noreply.github.com>

* Decompile func_80167F0C

* FbdemoWipe4 OK and documented

* Mark bug in Wipe4

* More docs

Co-authored-by: Tharo <17233964+Thar0@users.noreply.github.com>

* Mark bug

* Few more notes

* Fix function in Play

* Format

* Review

* Name Play_PostWorldDraw

* functions.h...

* Revert func_80167F0C

* Review

* functions.h

* Review

* Update Wipe4

* Rename system

* Format

* Put skeleton back in the cupboard

* bss

* Fix build

* rename to z_visfbuf

* review

* format

* bss

* some bss cleanup

* review

* bss

* review

---------

Co-authored-by: Tharo <17233964+Thar0@users.noreply.github.com>
Co-authored-by: angie <angheloalf95@gmail.com>

16 files changed, 490 insertions, 81 deletions

diff --git a/src/code/code_80140E80.c b/src/code/code_80140E80.c
deleted file mode 100644
index 56fcb663c..000000000
--- a/src/code/code_80140E80.c
+++ /dev/null
@@ -1,21 +0,0 @@
-#include "global.h"
-
-#pragma GLOBAL_ASM("asm/non_matchings/code/code_80140E80/func_80140E80.s")
-
-#pragma GLOBAL_ASM("asm/non_matchings/code/code_80140E80/func_80140EA0.s")
-
-#pragma GLOBAL_ASM("asm/non_matchings/code/code_80140E80/func_80140EAC.s")
-
-#pragma GLOBAL_ASM("asm/non_matchings/code/code_80140E80/func_80141008.s")
-
-#pragma GLOBAL_ASM("asm/non_matchings/code/code_80140E80/func_8014116C.s")
-
-#pragma GLOBAL_ASM("asm/non_matchings/code/code_80140E80/func_801411B4.s")
-
-#pragma GLOBAL_ASM("asm/non_matchings/code/code_80140E80/func_80141200.s")
-
-#pragma GLOBAL_ASM("asm/non_matchings/code/code_80140E80/func_8014151C.s")
-
-#pragma GLOBAL_ASM("asm/non_matchings/code/code_80140E80/func_80141678.s")
-
-#pragma GLOBAL_ASM("asm/non_matchings/code/code_80140E80/func_80141778.s")
diff --git a/src/code/z_actor.c b/src/code/z_actor.c
index e68f06809..f2b39de4e 100644
--- a/src/code/z_actor.c
+++ b/src/code/z_actor.c
@@ -4,12 +4,14 @@
  */
 
 #include "z64actor.h"
+#include "prevent_bss_reordering.h"
 #include "fault.h"
 #include "sys_cfb.h"
 #include "loadfragment.h"
 #include "z64horse.h"
 #include "z64quake.h"
 #include "z64rumble.h"
+
 #include "overlays/actors/ovl_En_Horse/z_en_horse.h"
 #include "overlays/actors/ovl_En_Part/z_en_part.h"
 #include "overlays/actors/ovl_En_Box/z_en_box.h"
diff --git a/src/code/z_bgcheck.c b/src/code/z_bgcheck.c
index 2bef40dce..f0807172c 100644
--- a/src/code/z_bgcheck.c
+++ b/src/code/z_bgcheck.c
@@ -1,3 +1,4 @@
+#include "prevent_bss_reordering.h"
 #include "global.h"
 #include "fault.h"
 #include "fixed_point.h"
diff --git a/src/code/z_camera.c b/src/code/z_camera.c
index d019ee395..56c6baf15 100644
--- a/src/code/z_camera.c
+++ b/src/code/z_camera.c
@@ -43,7 +43,6 @@
  *
  */
 
-#include "prevent_bss_reordering.h"
 #include "global.h"
 #include "libc/string.h"
 #include "z64quake.h"
diff --git a/src/code/z_collision_check.c b/src/code/z_collision_check.c
index 39b57cbd0..af1f4ad6c 100644
--- a/src/code/z_collision_check.c
+++ b/src/code/z_collision_check.c
@@ -1,3 +1,4 @@
+#include "prevent_bss_reordering.h"
 #include "global.h"
 #include "z64collision_check.h"
 
diff --git a/src/code/z_demo.c b/src/code/z_demo.c
index 1e3b74dfe..fa0419de4 100644
--- a/src/code/z_demo.c
+++ b/src/code/z_demo.c
@@ -1,3 +1,6 @@
+#include "prevent_bss_reordering.h"
+#include "prevent_bss_reordering2.h"
+
 #include "PR/ultratypes.h"
 
 // Variables are put before most headers as a hacky way to bypass bss reordering
@@ -11,16 +14,6 @@ static s16 sBssPad;
 u8 gDisablePlayerCsActionStartPos;
 s16 gDungeonBossWarpSceneId;
 
-#include "prevent_bss_reordering.h"
-#include "prevent_bss_reordering2.h"
-// clang-format off
-// Partial structs taken from "prevent_bss_reordering.h"
-struct Dummy200 { int x; };
-struct Dummy201 { int x; };
-struct Dummy202 { int x; };
-// clang-format on
-
-#include "global.h"
 #include "z64quake.h"
 #include "z64rumble.h"
 #include "z64shrink_window.h"
diff --git a/src/code/z_lifemeter.c b/src/code/z_lifemeter.c
index 5d1299bbf..d9abe151d 100644
--- a/src/code/z_lifemeter.c
+++ b/src/code/z_lifemeter.c
@@ -1,3 +1,4 @@
+#include "prevent_bss_reordering.h"
 #include "global.h"
 #include "overlays/kaleido_scope/ovl_kaleido_scope/z_kaleido_scope.h"
 #include "interface/parameter_static/parameter_static.h"
diff --git a/src/code/z_message.c b/src/code/z_message.c
index 3fb8f5bac..4d717d8df 100644
--- a/src/code/z_message.c
+++ b/src/code/z_message.c
@@ -5107,6 +5107,7 @@ void Message_Draw(PlayState* play) {
     GraphicsContext* gfxCtx = play->state.gfxCtx;
 
     OPEN_DISPS(gfxCtx);
+
     polyOpa = POLY_OPA_DISP;
     nextDisplayList = Graph_GfxPlusOne(polyOpa);
     gSPDisplayList(OVERLAY_DISP++, nextDisplayList);
@@ -5118,6 +5119,7 @@ void Message_Draw(PlayState* play) {
     gSPEndDisplayList(nextDisplayList++);
     Graph_BranchDlist(polyOpa, nextDisplayList);
     POLY_OPA_DISP = nextDisplayList;
+
     CLOSE_DISPS(gfxCtx);
 }
 
diff --git a/src/code/z_play.c b/src/code/z_play.c
index 5d9b2c048..17449e042 100644
--- a/src/code/z_play.c
+++ b/src/code/z_play.c
@@ -3,6 +3,7 @@
 #include "regs.h"
 #include "functions.h"
 #include "z64vismono.h"
+#include "z64visfbuf.h"
 
 // Variables are put before most headers as a hacky way to bypass bss reordering
 s16 sTransitionFillTimer;
@@ -11,8 +12,8 @@ TransitionTile sTransitionTile;
 s32 gTransitionTileState;
 VisMono sPlayVisMono;
 Color_RGBA8_u32 gVisMonoColor;
-Struct_80140E80 D_801F6D38;
-Struct_80140E80* D_801F6D4C;
+VisFbuf sPlayVisFbuf;
+VisFbuf* sPlayVisFbufInstance;
 BombersNotebook sBombersNotebook;
 u8 sBombersNotebookOpen;
 u8 sMotionBlurStatus;
@@ -417,8 +418,8 @@ void Play_Destroy(GameState* thisx) {
     ShrinkWindow_Destroy();
     TransitionFade_Destroy(&this->unk_18E48);
     VisMono_Destroy(&sPlayVisMono);
-    func_80140EA0(D_801F6D4C);
-    D_801F6D4C = NULL;
+    VisFbuf_Destroy(sPlayVisFbufInstance);
+    sPlayVisFbufInstance = NULL;
 
     if (CHECK_WEEKEVENTREG(WEEKEVENTREG_92_80)) {
         Actor_CleanupContext(&this->actorCtx, this);
@@ -1110,7 +1111,7 @@ void Play_PostWorldDraw(PlayState* this) {
         Gfx* opa;
         GraphicsContext* gfxCtx = this->state.gfxCtx;
 
-        D_801F6D4C->scale = gSaveContext.screenScale / 1000.0f;
+        sPlayVisFbufInstance->scale = gSaveContext.screenScale / 1000.0f;
 
         OPEN_DISPS(gfxCtx);
 
@@ -1118,7 +1119,7 @@ void Play_PostWorldDraw(PlayState* this) {
         nextOpa = Graph_GfxPlusOne(opa);
         gSPDisplayList(OVERLAY_DISP++, nextOpa);
 
-        func_80141778(D_801F6D4C, &nextOpa, this->unk_18E60, gfxCtx);
+        VisFbuf_Draw(sPlayVisFbufInstance, &nextOpa, this->unk_18E60);
 
         gSPEndDisplayList(nextOpa++);
         Graph_BranchDlist(opa, nextOpa);
@@ -2311,18 +2312,18 @@ void Play_Init(GameState* thisx) {
     VisMono_Init(&sPlayVisMono);
 
     gVisMonoColor.a = 0;
-    D_801F6D4C = &D_801F6D38;
-    func_80140E80(D_801F6D4C);
-    D_801F6D4C->lodProportion = 0.0f;
-    D_801F6D4C->mode = 1;
-    D_801F6D4C->primColor.r = 0;
-    D_801F6D4C->primColor.g = 0;
-    D_801F6D4C->primColor.b = 0;
-    D_801F6D4C->primColor.a = 0;
-    D_801F6D4C->envColor.r = 0;
-    D_801F6D4C->envColor.g = 0;
-    D_801F6D4C->envColor.b = 0;
-    D_801F6D4C->envColor.a = 0;
+    sPlayVisFbufInstance = &sPlayVisFbuf;
+    VisFbuf_Init(sPlayVisFbufInstance);
+    sPlayVisFbufInstance->lodProportion = 0.0f;
+    sPlayVisFbufInstance->mode = VIS_FBUF_MODE_GENERAL;
+    sPlayVisFbufInstance->primColor.r = 0;
+    sPlayVisFbufInstance->primColor.g = 0;
+    sPlayVisFbufInstance->primColor.b = 0;
+    sPlayVisFbufInstance->primColor.a = 0;
+    sPlayVisFbufInstance->envColor.r = 0;
+    sPlayVisFbufInstance->envColor.g = 0;
+    sPlayVisFbufInstance->envColor.b = 0;
+    sPlayVisFbufInstance->envColor.a = 0;
     CutsceneFlags_UnsetAll(this);
     THA_GetRemaining(&this->state.tha);
     zAllocSize = THA_GetRemaining(&this->state.tha);
diff --git a/src/code/z_visfbuf.c b/src/code/z_visfbuf.c
new file mode 100644
index 000000000..62242bcec
--- /dev/null
+++ b/src/code/z_visfbuf.c
@@ -0,0 +1,329 @@
+/**
+ * @file z_visfbuf.c
+ * @brief Copies images between color images (generally framebuffers), possibly with filling, scaling, and colour
+ * interpolation.
+ *
+ * Used for several transition effects, and in z_play to shrink the screen at the end of the First and Second Days.
+ *
+ * @note to use the functions in this file, with the exception of VisFbuf_Draw(), it is necessary to load the S2DEX2
+ * microcode first, and then re-load the 3D microcode afterwards for the rest of the drawing in the frame; see
+ * VisFbuf_Draw() for how to do this.
+ */
+
+#include "global.h"
+#include "z64visfbuf.h"
+#include "sys_cfb.h"
+
+#define SCALE_MIN 0.032f
+#define SCALE_MAX 1.0f //!< also unchanged scale
+
+void VisFbuf_Init(VisFbuf* this) {
+    bzero(this, sizeof(VisFbuf));
+}
+
+void VisFbuf_Destroy(VisFbuf* this) {
+}
+
+// internal, only used in VisFbuf_SetBg
+/**
+ * Draw a bg to the specified color image.
+ *
+ * @param[in,out] gfxP      Pointer to current displaylist
+ * @param[in]     bg        BG object to draw
+ * @param[out]    img       Pointer to beginning of destination color image
+ * @param[in]     width     Output width in pixels
+ * @param[in]     height    Output height in pixels
+ * @param[in]     cycleMode Which BG mode to use
+ */
+void VisFbuf_DrawBgToColorImage(Gfx** gfxP, uObjBg* bg, void* img, s32 width, s32 height, VisFbufBgMode cycleMode) {
+    Gfx* gfx = *gfxP;
+
+    gDPPipeSync(gfx++);
+    // Set up color image to draw bg to
+    gDPSetColorImage(gfx++, G_IM_FMT_RGBA, G_IM_SIZ_16b, width, img);
+    gDPSetScissor(gfx++, 0, 0, 0, width, height);
+
+    // Draw bg in appropriate type
+    gSPObjRenderMode(gfx++, G_OBJRM_ANTIALIAS | G_OBJRM_BILERP);
+    if (!!(cycleMode & VIS_FBUF_BG_CYC_COPY) != 0) { //! FAKE: may possibly be a better way
+        gSPBgRectCopy(gfx++, bg);
+    } else {
+        gSPBgRect1Cyc(gfx++, bg);
+    }
+
+    gDPPipeSync(gfx++);
+    // Reset the color image and scissor to frame's defaults
+    gDPSetColorImage(gfx++, G_IM_FMT_RGBA, G_IM_SIZ_16b, gCfbWidth, D_0F000000);
+    gSPDisplayList(gfx++, D_0E000000.setScissor);
+
+    *gfxP = gfx;
+}
+
+// internal
+/**
+ * Set up a BG from a specified source image and draw it to the specified color image with
+ * VisFbuf_DrawBgToColorImage(), using the BG's settings. Use VisFbuf_SetBgSimple() or
+ * VisFbuf_SetBgGeneral()
+ *
+ * @param[out] gfxP     Pointer to current displaylist
+ * @param[in] source    Pointer to beginning of source color image
+ * @param[out] img      Pointer to beginning of destination color image
+ * @param[in] width     Output width in pixels
+ * @param[in] height    Output height in pixels
+ * @param[in] x         Left of drawn output
+ * @param[in] y         Top of drawn output
+ * @param[in] scaleX    Amount to rescale the image, (dsdx). No effect if `cycleMode` is `VIS_FBUF_BG_CYC_COPY`.
+ * @param[in] scaleY    Amount to rescale the image, (dtdy). No effect if `cycleMode` is `VIS_FBUF_BG_CYC_COPY`.
+ * @param[in] cycleMode Which BG mode to use
+ */
+void VisFbuf_SetBg(Gfx** gfxP, void* source, void* img, s32 width, s32 height, f32 x, f32 y, f32 scaleX, f32 scaleY,
+                   VisFbufBgMode cycleMode) {
+    Gfx* gfx = *gfxP;
+    Gfx* gfxTemp;
+    uObjBg* bg;
+
+    // Allocate for BG
+    gfxTemp = gfx;
+    bg = Graph_DlistAlloc(&gfxTemp, sizeof(uObjBg));
+    gfx = gfxTemp;
+
+    // Set up BG
+    bg->b.imageX = 0;
+    bg->b.imageW = width << 2;
+    bg->b.frameX = x * 4;
+    bg->b.frameW = width << 2;
+    bg->b.imageY = 0;
+    bg->b.imageH = height << 2;
+    bg->b.frameY = y * 4;
+    bg->b.frameH = height << 2;
+    bg->b.imageLoad = G_BGLT_LOADTILE;
+    bg->b.imageFmt = G_IM_FMT_RGBA;
+    bg->b.imageSiz = G_IM_SIZ_16b;
+    bg->b.imagePal = 0;
+    bg->b.imageFlip = 0;
+    bg->b.imagePtr = source;
+
+    if (!!(cycleMode & VIS_FBUF_BG_CYC_COPY) != 0) { //! FAKE: may possibly be a better way
+        guS2DInitBg(bg);
+    } else {
+        bg->s.scaleW = (s32)((1 << 10) / scaleX);
+        bg->s.scaleH = (s32)((1 << 10) / scaleY);
+        bg->s.imageYorig = bg->b.imageY;
+    }
+
+    // draw BG to `img`
+    VisFbuf_DrawBgToColorImage(&gfx, bg, img, width, height, cycleMode);
+
+    *gfxP = gfx;
+}
+
+// used in FbdemoWipe5 and internally
+// "default settings" wrapper for VisFbuf_SetBg
+/**
+ * Set up a BG from a specified source image and draw it to the specified color image with
+ * VisFbuf_DrawBgToColorImage(), using the BG's settings. Position uses the default (0,0), and no rescaling is done
+ * even if 1-cycle mode is enabled.
+ *
+ * @see VisFbuf_SetBg() for arguments.
+ */
+void VisFbuf_SetBgSimple(Gfx** gfxP, void* source, void* img, s32 width, s32 height, VisFbufBgMode cycleMode) {
+    VisFbuf_SetBg(gfxP, source, img, width, height, 0.0f, 0.0f, SCALE_MAX, SCALE_MAX, cycleMode);
+}
+
+// wrapper for VisFbuf_SetBg with general arguments, used in VisFbuf_ApplyEffects
+/**
+ * Set up a BG from a specified source image and draw it to the specified color image with
+ * VisFbuf_DrawBgToColorImage(). Fully general settings are available.
+ *
+ * @see VisFbuf_SetBg() for arguments.
+ */
+void VisFbuf_SetBgGeneral(Gfx** gfxP, void* source, void* img, s32 width, s32 height, f32 x, f32 y, f32 scaleX,
+                          f32 scaleY, VisFbufBgMode cycleMode) {
+    VisFbuf_SetBg(gfxP, source, img, width, height, x, y, scaleX, scaleY, cycleMode);
+}
+
+// internal, used in VisFbuf_DrawGeneral
+/**
+ * Most general redrawing function.
+ *
+ *  - Copies `source` to `img`,
+ *  - fills the current framebuffer with `this->primColor`,
+ *  - applies colour interpolation to `img`,
+ *  - copies `img` back to `source`, with rescaling.
+ *
+ * @param[in]     this
+ * @param[in,out] gfxP   Pointer to current displaylist
+ * @param[in,out] source Pointer to beginning of in/out color image
+ * @param[out]    img    Pointer to beginning of destination color image
+ * @param[in]     width  Output width in pixels
+ * @param[in]     height Output height in pixels
+ */
+void VisFbuf_ApplyEffects(VisFbuf* this, Gfx** gfxP, void* source, void* img, s32 width, s32 height) {
+    Gfx* gfx = *gfxP;
+    s32 pad[3];
+
+    gDPPipeSync(gfx++);
+    // copy source to img
+    gDPSetOtherMode(gfx++,
+                    G_AD_PATTERN | G_CD_MAGICSQ | G_CK_NONE | G_TC_CONV | G_TF_POINT | G_TT_NONE | G_TL_TILE |
+                        G_TD_CLAMP | G_TP_NONE | G_CYC_COPY | G_PM_NPRIMITIVE,
+                    G_AC_NONE | G_ZS_PIXEL | G_RM_NOOP | G_RM_NOOP2);
+    VisFbuf_SetBgSimple(&gfx, source, img, width, height, VIS_FBUF_BG_CYC_COPY);
+
+    gDPPipeSync(gfx++);
+    // fill framebuffer with primColor
+    gDPSetOtherMode(gfx++,
+                    G_AD_PATTERN | G_CD_MAGICSQ | G_CK_NONE | G_TC_CONV | G_TF_POINT | G_TT_NONE | G_TL_TILE |
+                        G_TD_CLAMP | G_TP_NONE | G_CYC_FILL | G_PM_NPRIMITIVE,
+                    G_AC_NONE | G_ZS_PIXEL | G_RM_NOOP | G_RM_NOOP2);
+    {
+        s32 color = GPACK_RGBA5551(this->primColor.r, this->primColor.g, (u32)this->primColor.b, 1);
+
+        gDPSetFillColor(gfx++, (color << 0x10) | color);
+    }
+    //! @bug VisFbuf_SetBgSimple() sets the current color image back to the frame's default framebuffer at the end,
+    //! so this will always fill in the default framebuffer, whatever are used as `source` and `img`. This does not
+    //! arise in-game since this function is always used with `source = D_0F000000`.
+    gDPFillRectangle(gfx++, 0, 0, width - 1, height - 1);
+
+    gDPPipeSync(gfx++);
+    // Set lod and primColor from struct, perform interpolation, draw image with scaling (this is the most general
+    // alteration this system can carry out).
+    {
+        s32 lodFrac = this->lodProportion * 255;
+
+        gDPSetLODColor(gfx++, G_SETPRIMCOLOR, 0, lodFrac, this->primColor.rgba);
+    }
+    if (this->envColor.a == 0) {
+        // Interpolate between primColor and texel color using lod (but with max alpha)
+        gDPSetOtherMode(gfx++,
+                        G_AD_DISABLE | G_CD_DISABLE | G_CK_NONE | G_TC_FILT | G_TF_BILERP | G_TT_NONE | G_TL_TILE |
+                            G_TD_CLAMP | G_TP_NONE | G_CYC_1CYCLE | G_PM_NPRIMITIVE,
+                        G_AC_THRESHOLD | G_ZS_PIXEL | AA_EN | CVG_DST_CLAMP | ZMODE_OPA | CVG_X_ALPHA | ALPHA_CVG_SEL |
+                            GBL_c1(G_BL_CLR_IN, G_BL_A_IN, G_BL_CLR_BL, G_BL_1MA) |
+                            GBL_c2(G_BL_CLR_IN, G_BL_A_IN, G_BL_CLR_BL, G_BL_1MA));
+        gDPSetCombineLERP(gfx++, PRIMITIVE, TEXEL0, PRIM_LOD_FRAC, TEXEL0, 0, 0, 0, 1, PRIMITIVE, TEXEL0, PRIM_LOD_FRAC,
+                          TEXEL0, 0, 0, 0, 1);
+    } else {
+        // Interpolate between envColor (the new black) and primColor (the new white)
+        gDPSetOtherMode(gfx++,
+                        G_AD_DISABLE | G_CD_DISABLE | G_CK_NONE | G_TC_FILT | G_TF_POINT | G_TT_NONE | G_TL_TILE |
+                            G_TD_CLAMP | G_TP_NONE | G_CYC_1CYCLE | G_PM_NPRIMITIVE,
+                        G_AC_NONE | G_ZS_PIXEL | G_RM_CLD_SURF | G_RM_NOOP2);
+        gDPSetColor(gfx++, G_SETENVCOLOR, this->envColor.rgba);
+        gDPSetCombineLERP(gfx++, PRIMITIVE, ENVIRONMENT, TEXEL0, ENVIRONMENT, PRIMITIVE, ENVIRONMENT, TEXEL0,
+                          ENVIRONMENT, PRIMITIVE, ENVIRONMENT, TEXEL0, ENVIRONMENT, PRIMITIVE, ENVIRONMENT, TEXEL0,
+                          ENVIRONMENT);
+    }
+
+    // Draw scaled image in centre of `width * height` rectangle in `source`
+    {
+        f32 scale = CLAMP_ALT(this->scale, SCALE_MIN, SCALE_MAX);
+
+        VisFbuf_SetBgGeneral(&gfx, img, source, width, height, width * 0.5f * (1.0f - scale),
+                             height * 0.5f * (1.0f - scale), scale, scale, VIS_FBUF_BG_CYC_1CYC);
+    }
+
+    gDPPipeSync(gfx++);
+
+    *gfxP = gfx;
+}
+
+// internal, used in VisFbuf_Draw, VIS_FBUF_MODE_GENERAL
+/**
+ * If scale is within `(SCALE_MIN, SCALE_MAX)`, apply VisFbuf_ApplyEffects().
+ * If it is smaller than `SCALE_MIN`, fill the framebuffer with `this->primColor`
+ *
+ * @param[in]     this
+ * @param[in,out] gfxP   Pointer to current displaylist
+ * @param[in,out] source Pointer to beginning of source color image
+ * @param[in,out] img    Pointer to beginning of destination color image
+ * @param[in]     width  Output width in pixels
+ * @param[in]     height Output height in pixels
+ */
+void VisFbuf_DrawGeneral(VisFbuf* this, Gfx** gfxP, void* source, void* img, s32 width, s32 height) {
+    if (this->scale < SCALE_MAX) {
+        Gfx* gfx = *gfxP;
+        u32 color;
+
+        if (this->scale > SCALE_MIN) {
+            VisFbuf_ApplyEffects(this, &gfx, source, img, width, height);
+        } else {
+            gDPPipeSync(gfx++);
+            // fill the framebuffer with this->primColor
+            gDPSetOtherMode(gfx++,
+                            G_AD_PATTERN | G_CD_MAGICSQ | G_CK_NONE | G_TC_CONV | G_TF_POINT | G_TT_NONE | G_TL_TILE |
+                                G_TD_CLAMP | G_TP_NONE | G_CYC_FILL | G_PM_NPRIMITIVE,
+                            G_AC_NONE | G_ZS_PIXEL | G_RM_NOOP | G_RM_NOOP2);
+            color = GPACK_RGBA5551(this->primColor.r, this->primColor.g, (u32)this->primColor.b, 1);
+            gDPSetFillColor(gfx++, (color << 0x10) | color);
+            //! @bug See corresponding note in VisFbuf_ApplyEffects()
+            gDPFillRectangle(gfx++, 0, 0, width - 1, height - 1);
+
+            gDPPipeSync(gfx++);
+        }
+
+        *gfxP = gfx;
+    }
+}
+
+/**
+ * Redraw `img` in-place, using texel color to interpolate between envColor (the new black) and primColor (the new
+ * white)
+ *
+ * @param[in]     this
+ * @param[in,out] gfxP   Pointer to current displaylist
+ * @param[in,out] img    Pointer to beginning of color image to modify in-place
+ * @param[in]     width  width of img
+ * @param[in]     height height of img
+ */
+void VisFbuf_DrawInterpolate(VisFbuf* this, Gfx** gfxP, void* img, s32 width, s32 height) {
+    Gfx* gfx = *gfxP;
+
+    gDPPipeSync(gfx++);
+
+    gDPSetOtherMode(gfx++,
+                    G_AD_DISABLE | G_CD_DISABLE | G_CK_NONE | G_TC_FILT | G_TF_POINT | G_TT_NONE | G_TL_TILE |
+                        G_TD_CLAMP | G_TP_NONE | G_CYC_1CYCLE | G_PM_NPRIMITIVE,
+                    G_AC_NONE | G_ZS_PIXEL | G_RM_CLD_SURF | G_RM_NOOP2);
+    gDPSetColor(gfx++, G_SETPRIMCOLOR, this->primColor.rgba);
+    gDPSetColor(gfx++, G_SETENVCOLOR, this->envColor.rgba);
+    gDPSetCombineLERP(gfx++, PRIMITIVE, ENVIRONMENT, TEXEL0, ENVIRONMENT, PRIMITIVE, ENVIRONMENT, TEXEL0, ENVIRONMENT,
+                      PRIMITIVE, ENVIRONMENT, TEXEL0, ENVIRONMENT, PRIMITIVE, ENVIRONMENT, TEXEL0, ENVIRONMENT);
+    VisFbuf_SetBgSimple(&gfx, img, img, width, height, VIS_FBUF_BG_CYC_1CYC);
+
+    gDPPipeSync(gfx++);
+
+    *gfxP = gfx;
+}
+
+// used in Play and FbdemoWipe4
+/**
+ * main drawing function in this file, draws depending on settings specified in `this`.
+ *
+ * @param[in]     this
+ * @param[in,out] gfxP Pointer to current displaylist
+ * @param[in,out] img  Pointer to beginning of destination color image
+ */
+void VisFbuf_Draw(VisFbuf* this, Gfx** gfxP, void* img) {
+    Gfx* gfx = *gfxP;
+
+    gSPLoadUcodeL(gfx++, gspS2DEX2_fifo);
+
+    switch (this->mode) {
+        case VIS_FBUF_MODE_GENERAL:
+            VisFbuf_DrawGeneral(this, &gfx, D_0F000000, img, gScreenWidth, gScreenHeight);
+            break;
+
+        case VIS_FBUF_MODE_INTERPOLATE:
+            VisFbuf_DrawInterpolate(this, &gfx, D_0F000000, gScreenWidth, gScreenHeight);
+            break;
+
+        default:
+            break;
+    }
+
+    gSPLoadUcode(gfx++, SysUcode_GetUCode(), SysUcode_GetUCodeData());
+
+    *gfxP = gfx;
+}
diff --git a/src/overlays/actors/ovl_En_Fishing/z_en_fishing.c b/src/overlays/actors/ovl_En_Fishing/z_en_fishing.c
index 572327d15..4d2fc4db8 100644
--- a/src/overlays/actors/ovl_En_Fishing/z_en_fishing.c
+++ b/src/overlays/actors/ovl_En_Fishing/z_en_fishing.c
@@ -4,7 +4,6 @@
  * Description: Fishing Pond Elements (Owner, Fish, Props, Effects...)
  */
 
-#include "prevent_bss_reordering.h"
 #include "z_en_fishing.h"
 #include "z64rumble.h"
 #include "z64shrink_window.h"
diff --git a/src/overlays/fbdemos/ovl_fbdemo_wipe3/z_fbdemo_wipe3.c b/src/overlays/fbdemos/ovl_fbdemo_wipe3/z_fbdemo_wipe3.c
index b12a9cb76..543fc6e08 100644
--- a/src/overlays/fbdemos/ovl_fbdemo_wipe3/z_fbdemo_wipe3.c
+++ b/src/overlays/fbdemos/ovl_fbdemo_wipe3/z_fbdemo_wipe3.c
@@ -32,9 +32,9 @@ TransitionInit TransitionWipe3_InitVars = {
     TransitionWipe3_SetColor, TransitionWipe3_SetEnvColor, TransitionWipe3_IsDone,
 };
 
-#define TRANS3_GET_SPEED(type) (type & 1)
-#define TRANS3_GET_TEX_INDEX(type) ((type >> 1) & 7)
-#define TRANS3_GET_COLOR(type) ((type >> 4) & 3)
+#define TRANS3_GET_SPEED(type) ((type)&1)
+#define TRANS3_GET_TEX_INDEX(type) (((type) >> 1) & 7)
+#define TRANS3_GET_COLOR(type) (((type) >> 4) & 3)
 
 typedef enum {
     /* 0 */ TRANS_WIPE3_DIR_IN,
diff --git a/src/overlays/fbdemos/ovl_fbdemo_wipe4/z_fbdemo_wipe4.c b/src/overlays/fbdemos/ovl_fbdemo_wipe4/z_fbdemo_wipe4.c
index 1acb8c07a..562e1920b 100644
--- a/src/overlays/fbdemos/ovl_fbdemo_wipe4/z_fbdemo_wipe4.c
+++ b/src/overlays/fbdemos/ovl_fbdemo_wipe4/z_fbdemo_wipe4.c
@@ -1,11 +1,25 @@
-/*
- * File: z_fbdemo_wipe4.c
+/**
+ * @file z_fbdemo_wipe4.c
  * Overlay: ovl_fbdemo_wipe4
  * Description:
+ *
+ * @note The bug in TransitionWipe4_Draw() makes this transition do nothing apart from increase its timer until it is
+ * finished.
  */
 
 #include "global.h"
 #include "z_fbdemo_wipe4.h"
+#include "sys_cfb.h"
+
+#define THIS ((TransitionWipe4*)thisx)
+
+#define TRANS4_GET_COLORTYPE(type) (((type) >> 1) & 3)
+#define TRANS4_GET_SPEEDTYPE(type) ((type)&1)
+
+typedef enum TransitionWipe4Direction {
+    /* 0 */ TRANS_WIPE4_DIR_IN,
+    /* 1 */ TRANS_WIPE4_DIR_OUT
+} TransitionWipe4Direction;
 
 void* TransitionWipe4_Init(void* thisx);
 void TransitionWipe4_Destroy(void* thisx);
@@ -17,35 +31,115 @@ void TransitionWipe4_SetColor(void* thisx, u32 color);
 void TransitionWipe4_SetEnvColor(void* thisx, u32 color);
 s32 TransitionWipe4_IsDone(void* thisx);
 
-#if 0
 TransitionInit TransitionWipe4_InitVars = {
-    TransitionWipe4_Init,
-    TransitionWipe4_Destroy,
-    TransitionWipe4_Update,
-    TransitionWipe4_Draw,
-    TransitionWipe4_Start,
-    TransitionWipe4_SetType,
-    TransitionWipe4_SetColor,
-    TransitionWipe4_SetEnvColor,
-    TransitionWipe4_IsDone,
+    TransitionWipe4_Init,     TransitionWipe4_Destroy,     TransitionWipe4_Update,
+    TransitionWipe4_Draw,     TransitionWipe4_Start,       TransitionWipe4_SetType,
+    TransitionWipe4_SetColor, TransitionWipe4_SetEnvColor, TransitionWipe4_IsDone,
 };
 
-#endif
+void TransitionWipe4_Start(void* thisx) {
+    TransitionWipe4* this = (TransitionWipe4*)thisx;
+
+    this->isDone = false;
+
+    switch (this->speedType) {
+        default:
+            this->baseSpeed = 0.2f;
+            break;
+
+        case 0:
+            this->baseSpeed = 0.1f;
+            break;
+
+        case 1:
+            this->baseSpeed = 0.05f;
+            break;
+    }
+
+    switch (this->colorType) {
+        default:
+            this->primColor.rgba = RGBA8(160, 160, 160, 255);
+            break;
+
+        case 0:
+            this->primColor.rgba = RGBA8(0, 0, 0, 255);
+            break;
+
+        case 1:
+            this->primColor.rgba = RGBA8(160, 160, 160, 255);
+            break;
+    }
+}
+
+void* TransitionWipe4_Init(void* thisx) {
+    TransitionWipe4* this = (TransitionWipe4*)thisx;
+
+    bzero(this, sizeof(TransitionWipe4));
+
+    return this;
+}
+
+void TransitionWipe4_Destroy(void* thisx) {
+}
+
+void TransitionWipe4_Update(void* thisx, s32 updateRate) {
+    TransitionWipe4* this = (TransitionWipe4*)thisx;
+
+    this->progress += (this->baseSpeed * 3.0f) / updateRate;
+    if (this->progress >= 1.0f) {
+        this->progress = 1.0f;
+        this->isDone = true;
+    }
+}
+
+// Use of THIS in this function is required to match
+void TransitionWipe4_Draw(void* thisx, Gfx** gfxP) {
+    Gfx* gfx = *gfxP;
+    VisFbuf* copyFx = &THIS->copyFx;
+
+    copyFx->primColor.rgba = THIS->primColor.rgba;
+
+    if (THIS->direction != 0) {
+        copyFx->scale = THIS->progress;
+        copyFx->lodProportion = 1.0f - THIS->progress;
+    } else {
+        copyFx->scale = 1.0f - THIS->progress;
+        copyFx->lodProportion = THIS->progress;
+    }
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_fbdemo_wipe4/TransitionWipe4_Start.s")
+    //! @bug (Possibly) Since copyFx->mode is never set after being initialised to 0, the switch in VisFbuf_Draw()
+    //! does nothing, so this function call does nothing but change to the sprite microcode, then back to 3D microcode.
+    VisFbuf_Draw(copyFx, &gfx, SysCfb_GetZBuffer());
+    *gfxP = gfx;
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_fbdemo_wipe4/TransitionWipe4_Init.s")
+s32 TransitionWipe4_IsDone(void* thisx) {
+    TransitionWipe4* this = (TransitionWipe4*)thisx;
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_fbdemo_wipe4/TransitionWipe4_Destroy.s")
+    return this->isDone;
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_fbdemo_wipe4/TransitionWipe4_Update.s")
+void TransitionWipe4_SetType(void* thisx, s32 type) {
+    TransitionWipe4* this = (TransitionWipe4*)thisx;
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_fbdemo_wipe4/TransitionWipe4_Draw.s")
+    if (type & TRANS_TYPE_SET_PARAMS) {
+        this->colorType = TRANS4_GET_COLORTYPE(type);
+        this->speedType = TRANS4_GET_SPEEDTYPE(type);
+    } else if (type == TRANS_INSTANCE_TYPE_FILL_OUT) {
+        this->direction = TRANS_WIPE4_DIR_OUT;
+    } else {
+        this->direction = TRANS_WIPE4_DIR_IN;
+    }
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_fbdemo_wipe4/TransitionWipe4_IsDone.s")
+void TransitionWipe4_SetColor(void* thisx, u32 color) {
+    TransitionWipe4* this = (TransitionWipe4*)thisx;
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_fbdemo_wipe4/TransitionWipe4_SetType.s")
+    this->primColor.rgba = color;
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_fbdemo_wipe4/TransitionWipe4_SetColor.s")
+void TransitionWipe4_SetEnvColor(void* thisx, u32 color) {
+    TransitionWipe4* this = (TransitionWipe4*)thisx;
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_fbdemo_wipe4/TransitionWipe4_SetEnvColor.s")
+    this->envColor.rgba = color;
+}
diff --git a/src/overlays/fbdemos/ovl_fbdemo_wipe4/z_fbdemo_wipe4.h b/src/overlays/fbdemos/ovl_fbdemo_wipe4/z_fbdemo_wipe4.h
index b0aec44be..11357855a 100644
--- a/src/overlays/fbdemos/ovl_fbdemo_wipe4/z_fbdemo_wipe4.h
+++ b/src/overlays/fbdemos/ovl_fbdemo_wipe4/z_fbdemo_wipe4.h
@@ -3,9 +3,18 @@
 
 #include "ultra64.h"
 #include "color.h"
+#include "z64visfbuf.h"
 
-typedef struct {
-    /* 0x00 */ char unk_0[0x28];
+typedef struct TransitionWipe4 {
+    /* 0x00 */ Color_RGBA8_u32 primColor;
+    /* 0x04 */ Color_RGBA8_u32 envColor;
+    /* 0x08 */ f32 baseSpeed;
+    /* 0x0C */ f32 progress;
+    /* 0x10 */ u8 direction;
+    /* 0x11 */ u8 colorType;
+    /* 0x12 */ u8 speedType;
+    /* 0x13 */ u8 isDone;
+    /* 0x14 */ VisFbuf copyFx;
 } TransitionWipe4; // size = 0x28
 
 #endif
diff --git a/src/overlays/fbdemos/ovl_fbdemo_wipe5/z_fbdemo_wipe5.c b/src/overlays/fbdemos/ovl_fbdemo_wipe5/z_fbdemo_wipe5.c
index ee8aa689f..8e307efd4 100644
--- a/src/overlays/fbdemos/ovl_fbdemo_wipe5/z_fbdemo_wipe5.c
+++ b/src/overlays/fbdemos/ovl_fbdemo_wipe5/z_fbdemo_wipe5.c
@@ -94,7 +94,7 @@ void TransitionWipe5_Draw(void* thisx, Gfx** gfxP) {
                         G_AD_PATTERN | G_CD_MAGICSQ | G_CK_NONE | G_TC_CONV | G_TF_POINT | G_TT_NONE | G_TL_TILE |
                             G_TD_CLAMP | G_TP_NONE | G_CYC_COPY | G_PM_NPRIMITIVE,
                         G_AC_NONE | G_ZS_PIXEL | G_RM_NOOP | G_RM_NOOP2);
-        func_8014116C(&gfx, D_0F000000, workBuffer, width, height, 1);
+        VisFbuf_SetBgSimple(&gfx, D_0F000000, workBuffer, width, height, VIS_FBUF_BG_CYC_COPY);
     } else {
         if (alpha == 255) {
             gDPSetOtherMode(gfx++,
@@ -110,7 +110,7 @@ void TransitionWipe5_Draw(void* thisx, Gfx** gfxP) {
         gDPSetEnvColor(gfx++, 255, 255, 255, alpha);
         gDPSetCombineLERP(gfx++, TEXEL0, 0, ENVIRONMENT, 0, 0, 0, 0, ENVIRONMENT, TEXEL0, 0, ENVIRONMENT, 0, 0, 0, 0,
                           ENVIRONMENT);
-        func_8014116C(&gfx, workBuffer, D_0F000000, width, height, 0);
+        VisFbuf_SetBgSimple(&gfx, workBuffer, D_0F000000, width, height, VIS_FBUF_BG_CYC_1CYC);
     }
     gDPPipeSync(gfx++);
     gSPLoadUcode(gfx++, SysUcode_GetUCode(), SysUcode_GetUCodeData());
diff --git a/src/overlays/kaleido_scope/ovl_kaleido_scope/z_kaleido_scope_NES.c b/src/overlays/kaleido_scope/ovl_kaleido_scope/z_kaleido_scope_NES.c
index c99e6d718..fee889b6b 100644
--- a/src/overlays/kaleido_scope/ovl_kaleido_scope/z_kaleido_scope_NES.c
+++ b/src/overlays/kaleido_scope/ovl_kaleido_scope/z_kaleido_scope_NES.c
@@ -4,7 +4,6 @@
  * Description: Pause Menu
  */
 
-#include "prevent_bss_reordering.h"
 #include "z_kaleido_scope.h"
 #include "z64view.h"
 #include "overlays/gamestates/ovl_opening/z_opening.h"