From 7499c84d0b8dc49deabaa2162938bb6e4c2d4210 Mon Sep 17 00:00:00 2001
From: Mitch Richters <mjr4077au@gmail.com>
Date: Sat, 6 Nov 2021 14:00:41 +1100
Subject: [PATCH] - Add `interpolatedhorizon()` inlines to handle interpolating
 `fixedhoriz` objects without having to convert old and new values back to
 Q16.16 first.

---
 source/core/binaryangle.h             | 10 ++++++++++
 source/core/gameinput.h               |  2 +-
 source/games/blood/src/prediction.cpp |  4 ++--
 source/games/blood/src/view.cpp       | 10 ++--------
 source/games/duke/src/render.cpp      |  2 +-
 5 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/source/core/binaryangle.h b/source/core/binaryangle.h
index fcae89074..8fdd77a8e 100644
--- a/source/core/binaryangle.h
+++ b/source/core/binaryangle.h
@@ -405,3 +405,13 @@ inline constexpr binangle interpolatedangle(binangle oang, binangle ang, int con
 {
 	return bamang(oang.asbam() + MulScale(((ang.asbam() + 0x80000000 - oang.asbam()) & 0xFFFFFFFF) - 0x80000000, smoothratio, scale));
 }
+
+inline constexpr fixedhoriz interpolatedhorizon(fixedhoriz oval, fixedhoriz val, double const smoothratio, int const scale = 16)
+{
+	return q16horiz(oval.asq16() + MulScale((val - oval).asq16(), int(smoothratio), scale));
+}
+
+inline constexpr fixedhoriz interpolatedhorizon(fixedhoriz oval, fixedhoriz val, int const smoothratio, int const scale = 16)
+{
+	return q16horiz(oval.asq16() + MulScale((val - oval).asq16(), smoothratio, scale));
+}
diff --git a/source/core/gameinput.h b/source/core/gameinput.h
index b08b4b9f8..1920792aa 100644
--- a/source/core/gameinput.h
+++ b/source/core/gameinput.h
@@ -52,7 +52,7 @@ struct PlayerHorizon
 	// Commonly used getters.
 	fixedhoriz osum() { return ohoriz + ohorizoff; }
 	fixedhoriz sum() { return horiz + horizoff; }
-	fixedhoriz interpolatedsum(double const smoothratio) { return q16horiz(interpolatedvalue(osum().asq16(), sum().asq16(), smoothratio)); }
+	fixedhoriz interpolatedsum(double const smoothratio) { return interpolatedhorizon(osum(), sum(), smoothratio); }
 
 	// Ticrate playsim adjustment helpers.
 	void addadjustment(double value) { __addadjustment(buildfhoriz(value));	}
diff --git a/source/games/blood/src/prediction.cpp b/source/games/blood/src/prediction.cpp
index 44ced83a6..f09280d1e 100644
--- a/source/games/blood/src/prediction.cpp
+++ b/source/games/blood/src/prediction.cpp
@@ -248,12 +248,12 @@ static void fakeProcessInput(PLAYER *pPlayer, InputPacket *pInput)
         if (nSector2 == nSector)
         {
             int z2 = getflorzofslope(nSector2, x2, y2);
-            predict.horizoff = q16horiz(interpolatedvalue(predict.horizoff.asq16(), IntToFixed(z1 - z2) >> 3, 0x4000));
+            predict.horizoff = interpolatedhorizon(predict.horizoff, q16horiz((z1 - z2) << 13), 0x4000);
         }
     }
     else
     {
-        predict.horizoff = q16horiz(interpolatedvalue(predict.horizoff.asq16(), 0, 0x4000));
+        predict.horizoff = interpolatedhorizon(predict.horizoff, q16horiz(0), 0x4000);
         if (abs(predict.horizoff.asq16()) < 4)
             predict.horizoff = q16horiz(0);
     }
diff --git a/source/games/blood/src/view.cpp b/source/games/blood/src/view.cpp
index 3875d0cce..f367cdb5e 100644
--- a/source/games/blood/src/view.cpp
+++ b/source/games/blood/src/view.cpp
@@ -445,14 +445,8 @@ void SetupView(int &cX, int& cY, int& cZ, binangle& cA, fixedhoriz& cH, int& nSe
         }
         else
         {
-            auto oang = predictOld.angle + predictOld.look_ang;
-            auto ang = predict.angle + predict.look_ang;
-            cA = interpolatedangle(oang, ang, gInterpolate);
-
-            fixed_t ohoriz = (predictOld.horiz + predictOld.horizoff).asq16();
-            fixed_t horiz = (predict.horiz + predict.horizoff).asq16();
-            cH = q16horiz(interpolatedvalue(ohoriz, horiz, gInterpolate));
-
+            cA = interpolatedangle(predictOld.angle + predictOld.look_ang, predict.angle + predict.look_ang, gInterpolate);
+            cH = interpolatedhorizon(predictOld.horiz + predictOld.horizoff, predict.horiz + predict.horizoff, gInterpolate);
             rotscrnang = interpolatedangle(predictOld.rotscrnang, predict.rotscrnang, gInterpolate);
         }
     }
diff --git a/source/games/duke/src/render.cpp b/source/games/duke/src/render.cpp
index 0aae20676..e75de10fd 100644
--- a/source/games/duke/src/render.cpp
+++ b/source/games/duke/src/render.cpp
@@ -322,7 +322,7 @@ void displayrooms(int snum, double smoothratio)
 			cposz = interpolatedvalue(omyz, myz, smoothratio);
 			if (SyncInput())
 			{
-				choriz = q16horiz(interpolatedvalue((omyhoriz + omyhorizoff).asq16(), (myhoriz + myhorizoff).asq16(), smoothratio));
+				choriz = interpolatedhorizon(omyhoriz + omyhorizoff, myhoriz + myhorizoff, smoothratio);
 				cang = interpolatedangle(omyang, myang, smoothratio);
 			}
 			else