We can compile the slopes code now, yay! My brain hurts.

Compiling errors fixed in this commit:
* Various cases of mixed declaration and statement code
* Implicit declaration of slope functions (read: you forgot to put "include "p_slopes.h" in MORE than a few places)
* an odd case of a bad fixed_t to float typecase, cause by using P_GetZAt directly inside FIXED_TO_FLOAT
* a few minor cases of bad unsigned-signed comparisons
* no prototypes for some of the new slope functions. For goodness sake Red, this is basic stuff!

src/p_map.c

@@ -1245,11 +1245,13 @@ boolean P_CheckPosition(mobj_t *thing, fixed_t x, fixed_t y)
 
 		for (rover = newsubsec->sector->ffloors; rover; rover = rover->next)
 		{
+			fixed_t topheight, bottomheight;
+
 			if (!(rover->flags & FF_EXISTS))
 				continue;
 
-			fixed_t topheight = P_GetFOFTopZ(thing, newsubsec->sector, rover, x, y, NULL);
+			topheight = P_GetFOFTopZ(thing, newsubsec->sector, rover, x, y, NULL);
-			fixed_t bottomheight = P_GetFOFBottomZ(thing, newsubsec->sector, rover, x, y, NULL);
+			bottomheight = P_GetFOFBottomZ(thing, newsubsec->sector, rover, x, y, NULL);
 
 			if (rover->flags & FF_GOOWATER && !(thing->flags & MF_NOGRAVITY))
 			{
@@ -1549,11 +1551,12 @@ boolean P_CheckCameraPosition(fixed_t x, fixed_t y, camera_t *thiscam)
 
 		for (rover = newsubsec->sector->ffloors; rover; rover = rover->next)
 		{
+			fixed_t topheight, bottomheight;
 			if (!(rover->flags & FF_BLOCKOTHERS) || !(rover->flags & FF_EXISTS) || !(rover->flags & FF_RENDERALL) || GETSECSPECIAL(rover->master->frontsector->special, 4) == 12)
 				continue;
 
-			fixed_t topheight = P_CameraGetFOFTopZ(thiscam, newsubsec->sector, rover, x, y, NULL);
+			topheight = P_CameraGetFOFTopZ(thiscam, newsubsec->sector, rover, x, y, NULL);
-			fixed_t bottomheight = P_CameraGetFOFBottomZ(thiscam, newsubsec->sector, rover, x, y, NULL);
+			bottomheight = P_CameraGetFOFBottomZ(thiscam, newsubsec->sector, rover, x, y, NULL);
 
 			delta1 = thiscam->z - (bottomheight
 				+ ((topheight - bottomheight)/2));
@@ -3943,14 +3946,15 @@ fixed_t P_FloorzAtPos(fixed_t x, fixed_t y, fixed_t z, fixed_t height)
 
 		for (rover = sec->ffloors; rover; rover = rover->next)
 		{
+			fixed_t topheight, bottomheight;
 			if (!(rover->flags & FF_EXISTS))
 				continue;
 
 			if ((!(rover->flags & FF_SOLID || rover->flags & FF_QUICKSAND) || (rover->flags & FF_SWIMMABLE)))
 				continue;
 
-			fixed_t topheight = *rover->topheight;
+			topheight = *rover->topheight;
-			fixed_t bottomheight = *rover->bottomheight;
+			bottomheight = *rover->bottomheight;
 
 #ifdef ESLOPE
 			if (*rover->t_slope)

src/p_maputl.c

@@ -20,6 +20,7 @@
 #include "r_data.h"
 #include "p_maputl.h"
 #include "p_polyobj.h"
+#include "p_slopes.h"
 #include "z_zone.h"
 
 //
@@ -442,11 +443,12 @@ void P_CameraLineOpening(line_t *linedef)
 			if (front->ffloors)
 				for (rover = front->ffloors; rover; rover = rover->next)
 				{
+					fixed_t topheight, bottomheight;
 					if (!(rover->flags & FF_BLOCKOTHERS) || !(rover->flags & FF_RENDERALL) || !(rover->flags & FF_EXISTS) || GETSECSPECIAL(rover->master->frontsector->special, 4) == 12)
 						continue;
 
-					fixed_t topheight = P_CameraGetFOFTopZ(mapcampointer, front, rover, tmx, tmy, linedef);
+					topheight = P_CameraGetFOFTopZ(mapcampointer, front, rover, tmx, tmy, linedef);
-					fixed_t bottomheight = P_CameraGetFOFBottomZ(mapcampointer, front, rover, tmx, tmy, linedef);
+					bottomheight = P_CameraGetFOFBottomZ(mapcampointer, front, rover, tmx, tmy, linedef);
 
 					delta1 = abs(mapcampointer->z - (bottomheight + ((topheight - bottomheight)/2)));
 					delta2 = abs(thingtop - (bottomheight + ((topheight - bottomheight)/2)));
@@ -465,11 +467,12 @@ void P_CameraLineOpening(line_t *linedef)
 			if (back->ffloors)
 				for (rover = back->ffloors; rover; rover = rover->next)
 				{
+					fixed_t topheight, bottomheight;
 					if (!(rover->flags & FF_BLOCKOTHERS) || !(rover->flags & FF_RENDERALL) || !(rover->flags & FF_EXISTS) || GETSECSPECIAL(rover->master->frontsector->special, 4) == 12)
 						continue;
 
-					fixed_t topheight = P_CameraGetFOFTopZ(mapcampointer, back, rover, tmx, tmy, linedef);
+					topheight = P_CameraGetFOFTopZ(mapcampointer, back, rover, tmx, tmy, linedef);
-					fixed_t bottomheight = P_CameraGetFOFBottomZ(mapcampointer, back, rover, tmx, tmy, linedef);
+					bottomheight = P_CameraGetFOFBottomZ(mapcampointer, back, rover, tmx, tmy, linedef);
 
 					delta1 = abs(mapcampointer->z - (bottomheight + ((topheight - bottomheight)/2)));
 					delta2 = abs(thingtop - (bottomheight + ((topheight - bottomheight)/2)));
@@ -636,6 +639,7 @@ void P_LineOpening(line_t *linedef)
 			// Check for frontsector's fake floors
 			for (rover = front->ffloors; rover; rover = rover->next)
 			{
+				fixed_t topheight, bottomheight;
 				if (!(rover->flags & FF_EXISTS))
 					continue;
 
@@ -645,8 +649,8 @@ void P_LineOpening(line_t *linedef)
 					|| (rover->flags & FF_BLOCKOTHERS && !tmthing->player)))
 					continue;
 
-				fixed_t topheight = P_GetFOFTopZ(tmthing, front, rover, tmx, tmy, linedef);
+				topheight = P_GetFOFTopZ(tmthing, front, rover, tmx, tmy, linedef);
-				fixed_t bottomheight = P_GetFOFBottomZ(tmthing, front, rover, tmx, tmy, linedef);
+				bottomheight = P_GetFOFBottomZ(tmthing, front, rover, tmx, tmy, linedef);
 
 				delta1 = abs(tmthing->z - (bottomheight + ((topheight - bottomheight)/2)));
 				delta2 = abs(thingtop - (bottomheight + ((topheight - bottomheight)/2)));
@@ -679,6 +683,7 @@ void P_LineOpening(line_t *linedef)
 			// Check for backsectors fake floors
 			for (rover = back->ffloors; rover; rover = rover->next)
 			{
+				fixed_t topheight, bottomheight;
 				if (!(rover->flags & FF_EXISTS))
 					continue;
 
@@ -688,8 +693,8 @@ void P_LineOpening(line_t *linedef)
 					|| (rover->flags & FF_BLOCKOTHERS && !tmthing->player)))
 					continue;
 
-				fixed_t topheight = P_GetFOFTopZ(tmthing, back, rover, tmx, tmy, linedef);
+				topheight = P_GetFOFTopZ(tmthing, back, rover, tmx, tmy, linedef);
-				fixed_t bottomheight = P_GetFOFBottomZ(tmthing, back, rover, tmx, tmy, linedef);
+				bottomheight = P_GetFOFBottomZ(tmthing, back, rover, tmx, tmy, linedef);
 
 				delta1 = abs(tmthing->z - (bottomheight + ((topheight - bottomheight)/2)));
 				delta2 = abs(thingtop - (bottomheight + ((topheight - bottomheight)/2)));

src/p_mobj.c

@@ -696,6 +696,7 @@ void P_ExplodeMissile(mobj_t *mo)
 // Returns TRUE if mobj is inside a non-solid 3d floor.
 boolean P_InsideANonSolidFFloor(mobj_t *mobj, ffloor_t *rover)
 {
+	fixed_t topheight, bottomheight;
 	if (!(rover->flags & FF_EXISTS))
 		return false;
 
@@ -703,8 +704,8 @@ boolean P_InsideANonSolidFFloor(mobj_t *mobj, ffloor_t *rover)
 		|| ((rover->flags & FF_BLOCKOTHERS) && !mobj->player)))
 		return false;
 
-	fixed_t topheight = *rover->topheight;
+	topheight = *rover->topheight;
-	fixed_t bottomheight = *rover->bottomheight;
+	bottomheight = *rover->bottomheight;
 
 #ifdef ESLOPE
 	if (*rover->t_slope)
@@ -3006,13 +3007,14 @@ void P_MobjCheckWater(mobj_t *mobj)
 
 	for (rover = sector->ffloors; rover; rover = rover->next)
 	{
+		fixed_t topheight, bottomheight;
 		if (!(rover->flags & FF_EXISTS) || !(rover->flags & FF_SWIMMABLE)
 		 || (((rover->flags & FF_BLOCKPLAYER) && mobj->player)
 		 || ((rover->flags & FF_BLOCKOTHERS) && !mobj->player)))
 			continue;
 
-		fixed_t topheight = *rover->topheight;
+		topheight = *rover->topheight;
-		fixed_t bottomheight = *rover->bottomheight;
+		bottomheight = *rover->bottomheight;
 
 #ifdef ESLOPE
 		if (*rover->t_slope)

src/p_slopes.c

@@ -32,6 +32,7 @@
 #include "r_state.h"
 #include "m_bbox.h"
 #include "z_zone.h"
+#include "p_local.h"
 #include "p_spec.h"
 #include "p_slopes.h"
 #include "p_setup.h"
@@ -140,7 +141,8 @@ void P_RunDynamicSlopes(void) {
 		case 5: // vertices
 			{
 				mapthing_t *mt;
-				size_t i, l;
+				size_t i;
+				INT32 l;
 				line_t *line;
 
 				for (i = 0; i < 3; i++) {
@@ -322,7 +324,8 @@ void P_SpawnSlope_Line(int linenum)
 
 		if(frontfloor)
 		{
-
+			fixed_t highest, lowest;
+			size_t l;
 			point.z = line->frontsector->floorheight; // Startz
 			dz = FixedDiv(origin.z - point.z, extent); // Destinationz
 
@@ -351,12 +354,11 @@ void P_SpawnSlope_Line(int linenum)
 			// *You can use sourceline as a reference to see if two slopes really are the same
 
 			// Default points for high and low
-			fixed_t highest = point.z > origin.z ? point.z : origin.z;
+			highest = point.z > origin.z ? point.z : origin.z;
-			fixed_t lowest = point.z < origin.z ? point.z : origin.z;
+			lowest = point.z < origin.z ? point.z : origin.z;
 
 			// Now check to see what the REAL high and low points of the slope inside the sector
 			// TODO: Is this really needed outside of FOFs? -Red
-			size_t l;
 
 			for (l = 0; l < line->frontsector->linecount; l++)
 			{
@@ -380,6 +382,8 @@ void P_SpawnSlope_Line(int linenum)
 		}
 		if(frontceil)
 		{
+			fixed_t highest, lowest;
+			size_t l;
 			origin.z = line->backsector->ceilingheight;
 			point.z = line->frontsector->ceilingheight;
 			dz = FixedDiv(origin.z - point.z, extent);
@@ -396,9 +400,8 @@ void P_SpawnSlope_Line(int linenum)
 			cslope->sourceline = line;
 
 			// Remember the way the slope is formed
-			fixed_t highest = point.z > origin.z ? point.z : origin.z;
+			highest = point.z > origin.z ? point.z : origin.z;
-			fixed_t lowest = point.z < origin.z ? point.z : origin.z;
+			lowest = point.z < origin.z ? point.z : origin.z;
-			size_t l;
 
 			for (l = 0; l < line->frontsector->linecount; l++)
 			{
@@ -446,6 +449,8 @@ void P_SpawnSlope_Line(int linenum)
 
 		if(backfloor)
 		{
+			fixed_t highest, lowest;
+			size_t l;
 			point.z = line->backsector->floorheight;
 			dz = FixedDiv(origin.z - point.z, extent);
 
@@ -461,9 +466,8 @@ void P_SpawnSlope_Line(int linenum)
 			fslope->sourceline = line;
 
 			// Remember the way the slope is formed
-			fixed_t highest = point.z > origin.z ? point.z : origin.z;
+			highest = point.z > origin.z ? point.z : origin.z;
-			fixed_t lowest = point.z < origin.z ? point.z : origin.z;
+			lowest = point.z < origin.z ? point.z : origin.z;
-			size_t l;
 
 			for (l = 0; l < line->backsector->linecount; l++)
 			{
@@ -487,6 +491,8 @@ void P_SpawnSlope_Line(int linenum)
 		}
 		if(backceil)
 		{
+			fixed_t highest, lowest;
+			size_t l;
 			origin.z = line->frontsector->ceilingheight;
 			point.z = line->backsector->ceilingheight;
 			dz = FixedDiv(origin.z - point.z, extent);
@@ -503,10 +509,8 @@ void P_SpawnSlope_Line(int linenum)
 			cslope->sourceline = line;
 
 			// Remember the way the slope is formed
-			fixed_t highest = point.z > origin.z ? point.z : origin.z;
+			highest = point.z > origin.z ? point.z : origin.z;
-			fixed_t lowest = point.z < origin.z ? point.z : origin.z;
+			lowest = point.z < origin.z ? point.z : origin.z;
-
-			size_t l;
 
 			for (l = 0; l < line->backsector->linecount; l++)
 			{

src/p_slopes.h

@@ -29,6 +29,9 @@
 #define P_SLOPES_H__
 
 #ifdef ESLOPE
+void P_CalculateSlopeNormal(pslope_t *slope);
+void P_ReconfigureVertexSlope(pslope_t *slope);
+
 void P_ResetDynamicSlopes(void);
 void P_RunDynamicSlopes(void);
 // P_SpawnSlope_Line
@@ -36,6 +39,8 @@ void P_RunDynamicSlopes(void);
 // sectors.
 void P_SpawnSlope_Line(int linenum);
 
+pslope_t *P_NewVertexSlope(INT16 tag1, INT16 tag2, INT16 tag3, UINT8 flags);
+
 #ifdef SPRINGCLEAN
 // Loads just map objects that make slopes,
 // terrain affecting objects have to be spawned first

src/p_spec.c

@@ -29,6 +29,7 @@
 #include "r_main.h" //Two extra includes.
 #include "r_sky.h"
 #include "p_polyobj.h"
+#include "p_slopes.h"
 #include "hu_stuff.h"
 #include "m_misc.h"
 #include "m_cond.h" //unlock triggers
@@ -7043,7 +7044,7 @@ static void Add_Friction(INT32 friction, INT32 movefactor, INT32 affectee, INT32
   */
 void T_Friction(friction_t *f)
 {
-	sector_t *sec, *referrer;
+	sector_t *sec, *referrer = NULL;
 	mobj_t *thing;
 	msecnode_t *node;
 
@@ -7371,7 +7372,7 @@ static inline boolean PIT_PushThing(mobj_t *thing)
   */
 void T_Pusher(pusher_t *p)
 {
-	sector_t *sec, *referrer;
+	sector_t *sec, *referrer = NULL;
 	mobj_t *thing;
 	msecnode_t *node;
 	INT32 xspeed = 0,yspeed = 0;

src/p_user.c

@@ -29,6 +29,7 @@
 #include "m_random.h"
 #include "m_misc.h"
 #include "i_video.h"
+#include "p_slopes.h"
 #include "p_spec.h"
 #include "r_splats.h"
 #include "z_zone.h"
@@ -2317,11 +2318,11 @@ static void P_DoClimbing(player_t *player)
 		boolean thrust;
 		boolean boostup;
 		boolean skyclimber;
+		fixed_t floorheight, ceilingheight; // ESLOPE
 		thrust = false;
 		floorclimb = false;
 		boostup = false;
 		skyclimber = false;
-		fixed_t floorheight, ceilingheight; // ESLOPE
 
 #ifdef ESLOPE
 		floorheight = glidesector->sector->f_slope ? P_GetZAt(glidesector->sector->f_slope, player->mo->x, player->mo->y)

src/r_bsp.c

@@ -18,6 +18,7 @@
 
 #include "r_splats.h"
 #include "p_local.h" // camera
+#include "p_slopes.h"
 #include "z_zone.h" // Check R_Prep3DFloors
 
 seg_t *curline;

src/r_draw.h

@@ -65,9 +65,9 @@ typedef struct {
 	float x, y, z;
 } floatv3_t;
 
-pslope_t *ds_slope; // Current slope being used
+extern pslope_t *ds_slope; // Current slope being used
-floatv3_t ds_su, ds_sv, ds_sz; // Vectors for... stuff?
+extern floatv3_t ds_su, ds_sv, ds_sz; // Vectors for... stuff?
-float focallengthf, zeroheight;
+extern float focallengthf, zeroheight;
 #endif
 
 // Variable flat sizes
@@ -152,6 +152,7 @@ void R_DrawTranslatedColumn_8(void);
 void R_DrawTranslatedTranslucentColumn_8(void);
 void R_DrawSpan_8(void);
 #ifdef ESLOPE
+void R_CalcTiltedLighting(fixed_t start, fixed_t end);
 void R_DrawTiltedSpan_8(void);
 void R_DrawTiltedTranslucentSpan_8(void);
 void R_DrawTiltedSplat_8(void);

src/r_draw8.c

@@ -529,14 +529,14 @@ void R_DrawSpan_8 (void)
 #ifdef ESLOPE
 // R_CalcTiltedLighting
 // Exactly what it says on the tin. I wish I wasn't too lazy to explain things properly.
-static size_t tiltlighting[MAXVIDWIDTH];
+static INT32 tiltlighting[MAXVIDWIDTH];
 void R_CalcTiltedLighting(fixed_t start, fixed_t end)
 {
 	// ZDoom uses a different lighting setup to us, and I couldn't figure out how to adapt their version
 	// of this function. Here's my own.
 	INT32 left = ds_x1, right = ds_x2;
 	fixed_t step = (end-start)/(ds_x2-ds_x1+1);
-	size_t i;
+	INT32 i;
 
 	// I wanna do some optimizing by checking for out-of-range segments on either side to fill in all at once,
 	// but I'm too bad at coding to not crash the game trying to do that. I guess this is fast enough for now...
@@ -566,6 +566,11 @@ void R_DrawTiltedSpan_8(void)
 	UINT8 *colormap;
 	UINT8 *dest;
 
+	double startz, startu, startv;
+	double izstep, uzstep, vzstep;
+	double endz, endu, endv;
+	UINT32 stepu, stepv;
+
 	iz = ds_sz.z + ds_sz.y*(centery-ds_y) + ds_sz.x*(ds_x1-centerx);
 
 	// Lighting is simple. It's just linear interpolation from start to end
@@ -608,10 +613,9 @@ void R_DrawTiltedSpan_8(void)
 #define SPANSIZE 16
 #define INVSPAN	0.0625f
 
-	double startz = 1.f/iz;
+	startz = 1.f/iz;
-	double startu = uz*startz;
+	startu = uz*startz;
-	double startv = vz*startz;
+	startv = vz*startz;
-	double izstep, uzstep, vzstep;
 
 	izstep = ds_sz.x * SPANSIZE;
 	uzstep = ds_su.x * SPANSIZE;
@@ -625,11 +629,11 @@ void R_DrawTiltedSpan_8(void)
 		uz += uzstep;
 		vz += vzstep;
 
-		double endz = 1.f/iz;
+		endz = 1.f/iz;
-		double endu = uz*endz;
+		endu = uz*endz;
-		double endv = vz*endz;
+		endv = vz*endz;
-		UINT32 stepu = (INT64)((endu - startu) * INVSPAN);
+		stepu = (INT64)((endu - startu) * INVSPAN);
-		UINT32 stepv = (INT64)((endv - startv) * INVSPAN);
+		stepv = (INT64)((endv - startv) * INVSPAN);
 		u = (INT64)(startu) + viewx;
 		v = (INT64)(startv) + viewy;
 
@@ -661,12 +665,12 @@ void R_DrawTiltedSpan_8(void)
 			uz += ds_su.x * left;
 			vz += ds_sv.x * left;
 
-			double endz = 1.f/iz;
+			endz = 1.f/iz;
-			double endu = uz*endz;
+			endu = uz*endz;
-			double endv = vz*endz;
+			endv = vz*endz;
 			left = 1.f/left;
-			UINT32 stepu = (INT64)((endu - startu) * left);
+			stepu = (INT64)((endu - startu) * left);
-			UINT32 stepv = (INT64)((endv - startv) * left);
+			stepv = (INT64)((endv - startv) * left);
 			u = (INT64)(startu) + viewx;
 			v = (INT64)(startv) + viewy;
 
@@ -683,7 +687,6 @@ void R_DrawTiltedSpan_8(void)
 #endif
 }
 
-
 /**	\brief The R_DrawTiltedTranslucentSpan_8 function
 	Like DrawTiltedSpan, but translucent
 */
@@ -699,6 +702,11 @@ void R_DrawTiltedTranslucentSpan_8(void)
 	UINT8 *colormap;
 	UINT8 *dest;
 
+	double startz, startu, startv;
+	double izstep, uzstep, vzstep;
+	double endz, endu, endv;
+	UINT32 stepu, stepv;
+
 	iz = ds_sz.z + ds_sz.y*(centery-ds_y) + ds_sz.x*(ds_x1-centerx);
 
 	// Lighting is simple. It's just linear interpolation from start to end
@@ -741,10 +749,9 @@ void R_DrawTiltedTranslucentSpan_8(void)
 #define SPANSIZE 16
 #define INVSPAN	0.0625f
 
-	double startz = 1.f/iz;
+	startz = 1.f/iz;
-	double startu = uz*startz;
+	startu = uz*startz;
-	double startv = vz*startz;
+	startv = vz*startz;
-	double izstep, uzstep, vzstep;
 
 	izstep = ds_sz.x * SPANSIZE;
 	uzstep = ds_su.x * SPANSIZE;
@@ -758,11 +765,11 @@ void R_DrawTiltedTranslucentSpan_8(void)
 		uz += uzstep;
 		vz += vzstep;
 
-		double endz = 1.f/iz;
+		endz = 1.f/iz;
-		double endu = uz*endz;
+		endu = uz*endz;
-		double endv = vz*endz;
+		endv = vz*endz;
-		UINT32 stepu = (INT64)((endu - startu) * INVSPAN);
+		stepu = (INT64)((endu - startu) * INVSPAN);
-		UINT32 stepv = (INT64)((endv - startv) * INVSPAN);
+		stepv = (INT64)((endv - startv) * INVSPAN);
 		u = (INT64)(startu) + viewx;
 		v = (INT64)(startv) + viewy;
 
@@ -794,12 +801,12 @@ void R_DrawTiltedTranslucentSpan_8(void)
 			uz += ds_su.x * left;
 			vz += ds_sv.x * left;
 
-			double endz = 1.f/iz;
+			endz = 1.f/iz;
-			double endu = uz*endz;
+			endu = uz*endz;
-			double endv = vz*endz;
+			endv = vz*endz;
 			left = 1.f/left;
-			UINT32 stepu = (INT64)((endu - startu) * left);
+			stepu = (INT64)((endu - startu) * left);
-			UINT32 stepv = (INT64)((endv - startv) * left);
+			stepv = (INT64)((endv - startv) * left);
 			u = (INT64)(startu) + viewx;
 			v = (INT64)(startv) + viewy;
 
@@ -830,6 +837,11 @@ void R_DrawTiltedSplat_8(void)
 
 	UINT8 val;
 
+	double startz, startu, startv;
+	double izstep, uzstep, vzstep;
+	double endz, endu, endv;
+	UINT32 stepu, stepv;
+
 	iz = ds_sz.z + ds_sz.y*(centery-ds_y) + ds_sz.x*(ds_x1-centerx);
 
 	// Lighting is simple. It's just linear interpolation from start to end
@@ -874,10 +886,9 @@ void R_DrawTiltedSplat_8(void)
 #define SPANSIZE 16
 #define INVSPAN	0.0625f
 
-	double startz = 1.f/iz;
+	startz = 1.f/iz;
-	double startu = uz*startz;
+	startu = uz*startz;
-	double startv = vz*startz;
+	startv = vz*startz;
-	double izstep, uzstep, vzstep;
 
 	izstep = ds_sz.x * SPANSIZE;
 	uzstep = ds_su.x * SPANSIZE;
@@ -891,11 +902,11 @@ void R_DrawTiltedSplat_8(void)
 		uz += uzstep;
 		vz += vzstep;
 
-		double endz = 1.f/iz;
+		endz = 1.f/iz;
-		double endu = uz*endz;
+		endu = uz*endz;
-		double endv = vz*endz;
+		endv = vz*endz;
-		UINT32 stepu = (INT64)((endu - startu) * INVSPAN);
+		stepu = (INT64)((endu - startu) * INVSPAN);
-		UINT32 stepv = (INT64)((endv - startv) * INVSPAN);
+		stepv = (INT64)((endv - startv) * INVSPAN);
 		u = (INT64)(startu) + viewx;
 		v = (INT64)(startv) + viewy;
 
@@ -931,12 +942,12 @@ void R_DrawTiltedSplat_8(void)
 			uz += ds_su.x * left;
 			vz += ds_sv.x * left;
 
-			double endz = 1.f/iz;
+			endz = 1.f/iz;
-			double endu = uz*endz;
+			endu = uz*endz;
-			double endv = vz*endz;
+			endv = vz*endz;
 			left = 1.f/left;
-			UINT32 stepu = (INT64)((endu - startu) * left);
+			stepu = (INT64)((endu - startu) * left);
-			UINT32 stepv = (INT64)((endv - startv) * left);
+			stepv = (INT64)((endv - startv) * left);
 			u = (INT64)(startu) + viewx;
 			v = (INT64)(startv) + viewy;
 

src/r_plane.c

@@ -28,6 +28,8 @@
 
 #include "p_setup.h" // levelflats
 
+#include "p_slopes.h"
+
 //
 // opening
 //
@@ -952,6 +954,9 @@ void R_DrawSinglePlane(visplane_t *pl)
 		float ang;
 		float vx, vy, vz;
 		float fudge;
+		// compiler complains when P_GetZAt is used in FLOAT_TO_FIXED directly
+		// use this as a temp var to store P_GetZAt's return value each time
+		fixed_t temp;
 
 		xoffs &= ((1 << (32-nflatshiftup))-1);
 		yoffs &= ((1 << (32-nflatshiftup))-1);
@@ -969,7 +974,8 @@ void R_DrawSinglePlane(visplane_t *pl)
 		vy = FIXED_TO_FLOAT(viewy-yoffs);
 		vz = FIXED_TO_FLOAT(viewz);
 
-		zeroheight = FIXED_TO_FLOAT(P_GetZAt(pl->slope, viewx, viewy));
+		temp = P_GetZAt(pl->slope, viewx, viewy);
+		zeroheight = FIXED_TO_FLOAT(temp);
 
 #define ANG2RAD(angle) ((float)((angle)*M_PI)/ANGLE_180)
 
@@ -979,7 +985,8 @@ void R_DrawSinglePlane(visplane_t *pl)
 		ang = ANG2RAD(ANGLE_270 - viewangle);
 		p.x = vx * cos(ang) - vy * sin(ang);
 		p.z = vx * sin(ang) + vy * cos(ang);
-		p.y = FIXED_TO_FLOAT(P_GetZAt(pl->slope, -xoffs, yoffs)) - vz;
+		temp = P_GetZAt(pl->slope, -xoffs, yoffs);
+		p.y = FIXED_TO_FLOAT(temp) - vz;
 
 		// m is the v direction vector in view space
 		ang = ANG2RAD(ANGLE_180 - viewangle - pl->plangle);
@@ -991,8 +998,10 @@ void R_DrawSinglePlane(visplane_t *pl)
 		n.z = -cos(ang);
 
 		ang = ANG2RAD(pl->plangle);
-		m.y = FIXED_TO_FLOAT(P_GetZAt(pl->slope, viewx + FLOAT_TO_FIXED(sin(ang)), viewy + FLOAT_TO_FIXED(cos(ang)))) - zeroheight;
+		temp = P_GetZAt(pl->slope, viewx + FLOAT_TO_FIXED(sin(ang)), viewy + FLOAT_TO_FIXED(cos(ang)));
-		n.y = FIXED_TO_FLOAT(P_GetZAt(pl->slope, viewx + FLOAT_TO_FIXED(cos(ang)), viewy - FLOAT_TO_FIXED(sin(ang)))) - zeroheight;
+		m.y = FIXED_TO_FLOAT(temp) - zeroheight;
+		temp = P_GetZAt(pl->slope, viewx + FLOAT_TO_FIXED(cos(ang)), viewy - FLOAT_TO_FIXED(sin(ang)));
+		n.y = FIXED_TO_FLOAT(temp) - zeroheight;
 
 		m.x /= fudge;
 		m.y /= fudge;

src/r_segs.c

@@ -22,6 +22,7 @@
 #include "d_netcmd.h"
 #include "m_misc.h"
 #include "p_local.h" // Camera...
+#include "p_slopes.h"
 #include "console.h" // con_clipviewtop
 
 // OPTIMIZE: closed two sided lines as single sided
@@ -1489,7 +1490,7 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 	fixed_t       hyp;
 	fixed_t       sineval;
 	angle_t       distangle, offsetangle;
-	fixed_t       vtop;
+	//fixed_t       vtop;
 	INT32           lightnum;
 	INT32           i, p;
 	lightlist_t   *light;
@@ -1502,6 +1503,10 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 
 	maskedtextureheight = NULL;
 
+	//initialize segleft and segright
+	memset(&segleft, 0x00, sizeof(segleft));
+	memset(&segright, 0x00, sizeof(segright));
+
 	if (ds_p == drawsegs+maxdrawsegs)
 	{
 		size_t pos = ds_p - drawsegs;
@@ -2630,11 +2635,11 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 
 		{
 			ffloor_t * rover;
-			i = 0;
 #ifdef ESLOPE
 			fixed_t rovertest;
 			fixed_t planevistest;
 #endif
+			i = 0;
 
 			if (backsector->ffloors)
 			{

src/r_things.c

@@ -24,6 +24,7 @@
 #include "r_plane.h"
 #include "p_tick.h"
 #include "p_local.h"
+#include "p_slopes.h"
 #include "dehacked.h" // get_number (for thok)
 #include "d_netfil.h" // blargh. for nameonly().
 #include "m_cheat.h" // objectplace