From d0c3ed061c2e31b4428758ddb9572ee448abd8d6 Mon Sep 17 00:00:00 2001
From: lahm86 <33758420+lahm86@users.noreply.github.com>
Date: Tue, 25 Feb 2025 19:21:18 +0000
Subject: [PATCH] interpolation: handle specific effect deltas

This resolves the TR1 mutant missiles and TR2 flame blasts jittering.
---
 docs/tr1/CHANGELOG.md           |  1 +
 src/libtrx/game/interpolation.c | 34 ++++++++++++++++++++++++++++++---
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/docs/tr1/CHANGELOG.md b/docs/tr1/CHANGELOG.md
index bfa195605..cf1d61b65 100644
--- a/docs/tr1/CHANGELOG.md
+++ b/docs/tr1/CHANGELOG.md
@@ -1,6 +1,7 @@
 ## [Unreleased](https://github.com/LostArtefacts/TRX/compare/tr1-4.8.3...develop) - ××××-××-××
 - added support for custom levels to use `disable_floor` in the gameflow, similar to TR2's Floating Islands (#2541)
 - fixed issues with fixed cameras in 60 FPS shifting before settling on their target (#1186)
+- fixed missiles from mutants/centaurs/Natla jittering in 60 FPS (#1314)
 
 ## [4.8.3](https://github.com/LostArtefacts/TRX/compare/tr1-4.8.2...tr1-4.8.3) - 2025-02-17
 - fixed some of Lara's speech in the gym not playing in response to player action (#2514, regression from 4.8)
diff --git a/src/libtrx/game/interpolation.c b/src/libtrx/game/interpolation.c
index c6694a29d..7f2626493 100644
--- a/src/libtrx/game/interpolation.c
+++ b/src/libtrx/game/interpolation.c
@@ -88,6 +88,33 @@ static XYZ_32 M_GetItemMaxDelta(const ITEM *const item)
     return (XYZ_32) { .x = max_xz, .y = max_y, .z = max_xz };
 }
 
+static XYZ_32 M_GetEffectMaxDelta(const EFFECT *const effect)
+{
+    int32_t max_xz = 128;
+    int32_t max_y = MAX(128, effect->fall_speed * 2);
+    switch (effect->object_id) {
+#if TR_VERSION == 1
+    case O_MISSILE_1:
+    case O_MISSILE_3:
+#else
+    case O_MISSILE_FLAME:
+#endif
+        max_xz = 220;
+        break;
+
+#if TR_VERSION == 1
+    case O_MISSILE_2:
+        max_xz = 64;
+        break;
+#endif
+
+    default:
+        break;
+    }
+
+    return (XYZ_32) { .x = max_xz, .y = max_y, .z = max_xz };
+}
+
 bool Interpolation_IsEnabled(void)
 {
     return m_IsEnabled && M_GetFPS() == 60;
@@ -206,9 +233,10 @@ void Interpolation_Commit(void)
     int16_t effect_num = Effect_GetActiveNum();
     while (effect_num != NO_EFFECT) {
         EFFECT *const effect = Effect_Get(effect_num);
-        INTERPOLATE(effect, pos.x, ratio, 128);
-        INTERPOLATE(effect, pos.y, ratio, MAX(128, effect->fall_speed * 2));
-        INTERPOLATE(effect, pos.z, ratio, 128);
+        const XYZ_32 max_delta = M_GetEffectMaxDelta(effect);
+        INTERPOLATE(effect, pos.x, ratio, max_delta.x);
+        INTERPOLATE(effect, pos.y, ratio, max_delta.y);
+        INTERPOLATE(effect, pos.z, ratio, max_delta.z);
         INTERPOLATE_ROT(effect, rot.x, ratio, DEG_45);
         INTERPOLATE_ROT(effect, rot.y, ratio, DEG_45);
         INTERPOLATE_ROT(effect, rot.z, ratio, DEG_45);