From 26f54b0ba49d3f32b95d9849f066d835ff18003a Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <c.oelckers@zdoom.fake>
Date: Thu, 28 Apr 2016 12:18:33 +0200
Subject: [PATCH] - eliminated tantoangle and cleaned up r_tables.h

---
 src/r_main.cpp    |  6 ++++--
 src/r_utility.cpp | 24 +----------------------
 src/tables.cpp    |  2 --
 src/tables.h      | 50 -----------------------------------------------
 4 files changed, 5 insertions(+), 77 deletions(-)

diff --git a/src/r_main.cpp b/src/r_main.cpp
index 0249544eb..072b03887 100644
--- a/src/r_main.cpp
+++ b/src/r_main.cpp
@@ -221,7 +221,6 @@ void R_InitTextureMapping ()
 
 	const int t1 = MAX(int(CenterX - FocalLengthX), 0);
 	const int t2 = MIN(int(CenterX + FocalLengthX), viewwidth);
-	const fixed_t dfocus = FLOAT2FIXED(FocalLengthX) >> DBITS;
 
 	for (i = 0, x = t2; x >= t1; --x)
 	{
@@ -233,7 +232,10 @@ void R_InitTextureMapping ()
 	}
 	for (x = t2 + 1; x <= viewwidth; ++x)
 	{
-		xtoviewangle[x] = ANGLE_270 + tantoangle[dfocus / (x - centerx)];
+		double f = atan2((FocalLengthX / (x - centerx)), 1) / (2*M_PI);
+		xtoviewangle[x] = ANGLE_270 + (angle_t)(0xffffffff * f);
+
+		//xtoviewangle[x] = ANGLE_270 + tantoangle[i];
 	}
 	for (x = 0; x < t1; ++x)
 	{
diff --git a/src/r_utility.cpp b/src/r_utility.cpp
index 1dd4e5e40..2374c9eea 100644
--- a/src/r_utility.cpp
+++ b/src/r_utility.cpp
@@ -158,27 +158,6 @@ DAngle viewpitch;
 // CODE --------------------------------------------------------------------
 static void R_Shutdown ();
 
-//==========================================================================
-//
-// R_InitPointToAngle
-//
-//==========================================================================
-
-void R_InitPointToAngle (void)
-{
-	double f;
-	int i;
-//
-// slope (tangent) to angle lookup
-//
-	for (i = 0; i <= SLOPERANGE; i++)
-	{
-		f = g_atan2 ((double)i, (double)SLOPERANGE) / (6.28318530718 /* 2*pi */);
-		tantoangle[i] = (angle_t)(0xffffffff*f);
-	}
-}
-
-
 //==========================================================================
 //
 // R_InitTables
@@ -188,7 +167,7 @@ void R_InitPointToAngle (void)
 void R_InitTables (void)
 {
 	int i;
-	const double pimul = PI*2/FINEANGLES;
+	const double pimul = M_PI*2/FINEANGLES;
 
 	// viewangle tangent table
 	finetangent[0] = (fixed_t)(FRACUNIT*g_tan ((0.5-FINEANGLES/4)*pimul)+0.5);
@@ -410,7 +389,6 @@ void R_Init ()
 	//R_InitColormaps ();
 	//StartScreen->Progress();
 
-	R_InitPointToAngle ();
 	R_InitTables ();
 	R_InitTranslationTables ();
 	R_SetViewSize (screenblocks);
diff --git a/src/tables.cpp b/src/tables.cpp
index 9e367d349..9679e8547 100644
--- a/src/tables.cpp
+++ b/src/tables.cpp
@@ -37,6 +37,4 @@
 
 fixed_t finetangent[4096];
 fixed_t finesine[10240];
-angle_t tantoangle[2049];
 
-cosine_inline finecosine;	// in case this is actually needed
diff --git a/src/tables.h b/src/tables.h
index 085174892..e2cf93e63 100644
--- a/src/tables.h
+++ b/src/tables.h
@@ -24,11 +24,8 @@
 //		effectively, by shifting).
 //
 //		int finesine[10240] 			- Sine lookup.
-//		 Guess what, serves as cosine, too.
 //		 Remarkable thing is, how to use BAMs with this? 
 //
-//		int tantoangle[2049]	- ArcTan LUT,
-//		  maps tan(angle) to angle fast. Gotta search.	
 //	  
 //-----------------------------------------------------------------------------
 
@@ -40,72 +37,25 @@
 #include <math.h>
 #include "basictypes.h"
 
-#ifndef PI
-#define PI				3.14159265358979323846		// matches value in gcc v2 math.h
-#endif
-
-
-#define FINEANGLEBITS	13
 #define FINEANGLES		8192
 #define FINEMASK		(FINEANGLES-1)
 
 // 0x100000000 to 0x2000
 #define ANGLETOFINESHIFT		19
 
-#define BOBTOFINESHIFT			(FINEANGLEBITS - 6)
-
 // Effective size is 10240.
 extern	fixed_t 		finesine[5*FINEANGLES/4];
 
-// Re-use data, is just PI/2 phase shift.
-// [RH] Instead of using a pointer, use some inline code
-// (encapsulated in a struct so that we can still use array accesses).
-struct cosine_inline
-{
-	fixed_t operator[] (unsigned int x) const
-	{
-		return finesine[x+FINEANGLES/4];
-	}
-};
-extern cosine_inline finecosine;
-
 // Effective size is 4096.
 extern fixed_t			finetangent[FINEANGLES/2];
 
 // Binary Angle Measument, BAM.
-#define ANG45			(0x20000000)
-#define ANG90			(0x40000000)
-#define ANG180			(0x80000000)
-#define ANG270			(0xc0000000)
-
-#define ANGLE_45		(0x20000000)
 #define ANGLE_90		(0x40000000)
 #define ANGLE_180		(0x80000000)
 #define ANGLE_270		(0xc0000000)
 #define ANGLE_MAX		(0xffffffff)
-#define ANGLE_1			(ANGLE_45/45)
-#define ANGLE_60		(ANGLE_180/3)
 
 
-#define SLOPERANGE		2048
-#define SLOPEBITS		11
-#define DBITS			(FRACBITS-SLOPEBITS)
-
 typedef uint32			angle_t;
 
-// Previously seen all over the place, code like this:  abs(ang1 - ang2)
-// Clang warns (and is absolutely correct) that technically, this
-// could be optimized away and do nothing:
-//   warning: taking the absolute value of unsigned type 'unsigned int' has no effect
-//   note: remove the call to 'abs' since unsigned values cannot be negative
-inline angle_t absangle(angle_t a)
-{
-	return (angle_t)abs((int32_t)a);
-}
-
-// Effective size is 2049;
-// The +1 size is to handle the case when x==y
-//	without additional checking.
-extern angle_t			tantoangle[SLOPERANGE+1];
-
 #endif // __TABLES_H__