Fix mirror decal not rendering on some walls (#7052)

3 files changed, 26 insertions, 1 deletions

diff --git a/soh/soh/Enhancements/AlwaysOnFixes.cpp b/soh/soh/Enhancements/AlwaysOnFixes.cpp
index 639330f68..66c270c22 100644
--- a/soh/soh/Enhancements/AlwaysOnFixes.cpp
+++ b/soh/soh/Enhancements/AlwaysOnFixes.cpp
@@ -8,6 +8,7 @@ extern "C" {
 #include "include/z64camera.h"
 #include "src/overlays/actors/ovl_En_Test/z_en_test.h"
 #include "src/overlays/actors/ovl_En_Horse/z_en_horse.h"
+#include "src/overlays/actors/ovl_Mir_Ray/z_mir_ray.h"
 void UnregisterActorSkeletons(struct Actor* actor);
 extern void Player_UseItem(PlayState*, Player*, s32);
 extern PlayState* gPlayState;
@@ -110,6 +111,20 @@ void RegisterAlwaysOnFixes() {
         }
     });
 
+    // Mir_Ray draws the reflection image straight on the collision poly's plane, but CollisionPoly
+    // stores that plane quantized (s16 normal, integer dist), so for about half of all walls it
+    // lands a fraction of a unit inside the drawn surface. N64 RDP's decal mode handled that,
+    // but our graphics pipeline does not. Lift the image off the plane along the poly normal.
+    COND_VB_SHOULD(VB_MIRRAY_DRAW_REFLECTION, true, {
+        if (*should) {
+            MirRayShieldReflection* reflection = va_arg(args, MirRayShieldReflection*);
+            CollisionPoly* poly = reflection->reflectionPoly;
+            reflection->pos.x += COLPOLY_GET_NORMAL(poly->normal.x);
+            reflection->pos.y += COLPOLY_GET_NORMAL(poly->normal.y);
+            reflection->pos.z += COLPOLY_GET_NORMAL(poly->normal.z);
+        }
+    });
+
     // Handle first person aiming camera settings
     COND_VB_SHOULD(VB_CHANGE_AIMING_CAMERA, true, {
         s8* heldItemAction = va_arg(args, s8*);
diff --git a/soh/soh/Enhancements/game-interactor/vanilla-behavior/GIVanillaBehavior.h b/soh/soh/Enhancements/game-interactor/vanilla-behavior/GIVanillaBehavior.h
index f0b91582c..e41669089 100644
--- a/soh/soh/Enhancements/game-interactor/vanilla-behavior/GIVanillaBehavior.h
+++ b/soh/soh/Enhancements/game-interactor/vanilla-behavior/GIVanillaBehavior.h
@@ -1642,6 +1642,14 @@ typedef enum {
 
     // #### `result`
     // ```c
+    // reflection[i].reflectionPoly != NULL
+    // ```
+    // #### `args`
+    // - `*MirRayShieldReflection`
+    VB_MIRRAY_DRAW_REFLECTION,
+
+    // #### `result`
+    // ```c
     // false
     // ```
     // #### `args`
diff --git a/soh/src/overlays/actors/ovl_Mir_Ray/z_mir_ray.c b/soh/src/overlays/actors/ovl_Mir_Ray/z_mir_ray.c
index 334c1fdf6..ae1b130bd 100644
--- a/soh/src/overlays/actors/ovl_Mir_Ray/z_mir_ray.c
+++ b/soh/src/overlays/actors/ovl_Mir_Ray/z_mir_ray.c
@@ -7,6 +7,7 @@
 #include "z_mir_ray.h"
 #include "objects/object_mir_ray/object_mir_ray.h"
 #include "soh/frame_interpolation.h"
+#include "soh/Enhancements/game-interactor/GameInteractor_Hooks.h"
 
 #define FLAGS (ACTOR_FLAG_UPDATE_CULLING_DISABLED | ACTOR_FLAG_DRAW_CULLING_DISABLED)
 
@@ -510,7 +511,8 @@ void MirRay_Draw(Actor* thisx, PlayState* play) {
                 }
             }
             for (i = 0; i < 6; i++) {
-                if (reflection[i].reflectionPoly != NULL) {
+                if (GameInteractor_Should(VB_MIRRAY_DRAW_REFLECTION, reflection[i].reflectionPoly != NULL,
+                                          &reflection[i])) {
                     FrameInterpolation_RecordOpenChild(&reflection[i], i);
                     Matrix_Translate(reflection[i].pos.x, reflection[i].pos.y, reflection[i].pos.z, MTXMODE_NEW);
                     Matrix_Scale(0.01f, 0.01f, 0.01f, MTXMODE_APPLY);