From 15e809d65b7dc5c10f15f31d0738dc6d35618c49 Mon Sep 17 00:00:00 2001
From: Skyth <19259897+blueskythlikesclouds@users.noreply.github.com>
Date: Mon, 6 Jan 2025 16:14:56 +0300
Subject: [PATCH] Interpolate to original 4:3 scale.

---
 UnleashedRecomp/patches/csd_patches.cpp | 31 +++++++++++++------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/UnleashedRecomp/patches/csd_patches.cpp b/UnleashedRecomp/patches/csd_patches.cpp
index c8db64d5..b56c4a1a 100644
--- a/UnleashedRecomp/patches/csd_patches.cpp
+++ b/UnleashedRecomp/patches/csd_patches.cpp
@@ -175,8 +175,8 @@ PPC_FUNC(sub_825E2E60)
 static constexpr float NARROW_ASPECT_RATIO = 4.0f / 3.0f;
 static constexpr float WIDE_ASPECT_RATIO = 16.0f / 9.0f;
 static constexpr float STEAM_DECK_ASPECT_RATIO = 16.0f / 10.0f;
-static constexpr float INV_WIDE_ASPECT_RATIO = 1.0f / WIDE_ASPECT_RATIO;
-static constexpr float INV_WIDE_SCALE = 1280.0f / 960.0f;
+static constexpr float TALL_ASPECT_RATIO = 1.0f / WIDE_ASPECT_RATIO;
+static constexpr float TALL_SCALE = 1280.0f / 960.0f;
 
 static float g_offsetX;
 static float g_offsetY;
@@ -184,6 +184,11 @@ static float g_scale;
 
 static float g_worldMapOffset;
 
+static float ComputeScale(float aspectRatio)
+{
+    return ((aspectRatio * 720.0f) / 1280.0f) / sqrt((aspectRatio * 720.0f) / 1280.0f);
+}
+
 static void ComputeOffsets(float width, float height)
 {
     float aspectRatio = width / height;
@@ -195,12 +200,15 @@ static void ComputeOffsets(float width, float height)
         g_offsetX = 0.5f * (aspectRatio * 720.0f - 1280.0f);
         g_offsetY = 0.0f;
 
-        // narrow resolutions will zoom the UI in, but we want the gameplay
-        // UI to retain the same scale at Steam Deck's aspect ratio
+        // keep same scale above Steam Deck aspect ratio
         if (aspectRatio < WIDE_ASPECT_RATIO)
         {
-            float factor = std::clamp((aspectRatio - NARROW_ASPECT_RATIO) / (STEAM_DECK_ASPECT_RATIO - NARROW_ASPECT_RATIO), 0.0f, 1.0f);
-            g_scale = 1.0f + factor * (aspectRatio / WIDE_ASPECT_RATIO - 1.0f);
+            // interpolate to original 4:3 scale
+            float steamDeckScale = aspectRatio / WIDE_ASPECT_RATIO;
+            float narrowScale = ComputeScale(NARROW_ASPECT_RATIO);
+
+            float lerpFactor = std::clamp((aspectRatio - NARROW_ASPECT_RATIO) / (STEAM_DECK_ASPECT_RATIO - NARROW_ASPECT_RATIO), 0.0f, 1.0f);
+            g_scale = narrowScale + (steamDeckScale - narrowScale) * lerpFactor;
         }
     }
     else
@@ -210,17 +218,10 @@ static void ComputeOffsets(float width, float height)
         g_offsetY = 0.5f * (960.0f / aspectRatio - 720.0f);
 
         // scale to 16:9 as the aspect ratio becomes 9:16
-        float factor = std::clamp((aspectRatio - INV_WIDE_ASPECT_RATIO) / (NARROW_ASPECT_RATIO - INV_WIDE_ASPECT_RATIO), 0.0f, 1.0f);
-        g_scale = INV_WIDE_SCALE + factor * (1.0f - INV_WIDE_SCALE);
+        float factor = std::clamp((aspectRatio - TALL_ASPECT_RATIO) / (NARROW_ASPECT_RATIO - TALL_ASPECT_RATIO), 0.0f, 1.0f);
+        g_scale = TALL_SCALE + factor * (ComputeScale(NARROW_ASPECT_RATIO) - TALL_SCALE);
     } 
 
-    // use original 4:3 scaling if requested
-    if (Config::AspectRatio == EAspectRatio::OriginalNarrow)
-    {
-        aspectRatio = std::clamp(aspectRatio, NARROW_ASPECT_RATIO, WIDE_ASPECT_RATIO);
-        g_scale = ((aspectRatio * 720.0f) / 1280.0f) / sqrt((aspectRatio * 720.0f) / 1280.0f);
-    }
-
     g_worldMapOffset = std::clamp((aspectRatio - NARROW_ASPECT_RATIO) / (WIDE_ASPECT_RATIO - NARROW_ASPECT_RATIO), 0.0f, 1.0f);
 }