From 1f97488945ab15a72f89a4099334aaa42acdd9bd Mon Sep 17 00:00:00 2001
From: Randy Heit <rheit@users.noreply.github.com>
Date: Thu, 21 Apr 2016 20:17:02 -0500
Subject: [PATCH] Renderer floatification: Use floating point for decals

---
 src/r_segs.cpp   | 28 +++++++++++-----------------
 src/r_things.cpp |  7 +++----
 2 files changed, 14 insertions(+), 21 deletions(-)

diff --git a/src/r_segs.cpp b/src/r_segs.cpp
index e689e5a89..6d71fc11e 100644
--- a/src/r_segs.cpp
+++ b/src/r_segs.cpp
@@ -3032,8 +3032,7 @@ static void R_RenderDecal (side_t *wall, DBaseDecal *decal, drawseg_t *clipper,
 {
 	DVector2 decal_left, decal_right, decal_pos;
 	int x1, x2;
-	fixed_t xscale, yscale;
-	fixed_t topoff;
+	double yscale;
 	BYTE flipx;
 	double zpos;
 	int needrepeat = 0;
@@ -3085,9 +3084,6 @@ static void R_RenderDecal (side_t *wall, DBaseDecal *decal, drawseg_t *clipper,
 		}
 	}
 
-	xscale = FLOAT2FIXED(decal->ScaleX);
-	yscale = FLOAT2FIXED(decal->ScaleY);
-
 	WallSpriteTile = TexMan(decal->PicNum, true);
 	flipx = (BYTE)(decal->RenderFlags & RF_XFLIP);
 
@@ -3102,12 +3098,10 @@ static void R_RenderDecal (side_t *wall, DBaseDecal *decal, drawseg_t *clipper,
 
 	FWallCoords savecoord = WallC;
 
-	x2 = WallSpriteTile->GetWidth();
-	x1 = WallSpriteTile->LeftOffset;
-	x2 = x2 - x1;
-
-	x1 *= xscale;
-	x2 *= xscale;
+	double edge_right = WallSpriteTile->GetWidth();
+	double edge_left = WallSpriteTile->LeftOffset;
+	edge_right = (edge_right - edge_left) * decal->ScaleX;
+	edge_left *= decal->ScaleX;
 
 	double dcx, dcy;
 	decal->GetXY(wall, dcx, dcy);
@@ -3115,8 +3109,8 @@ static void R_RenderDecal (side_t *wall, DBaseDecal *decal, drawseg_t *clipper,
 
 	DVector2 angvec = (curline->v2->fPos() - curline->v1->fPos()).Unit();
 
-	decal_left = decal_pos - x1 * angvec - ViewPos;
-	decal_right = decal_pos + x2 * angvec - ViewPos;
+	decal_left = decal_pos - edge_left * angvec - ViewPos;
+	decal_right = decal_pos + edge_right * angvec - ViewPos;
 
 	if (WallC.Init(decal_left, decal_right, TOO_CLOSE_Z))
 		goto done;
@@ -3183,8 +3177,8 @@ static void R_RenderDecal (side_t *wall, DBaseDecal *decal, drawseg_t *clipper,
 		break;
 	}
 
-	topoff = WallSpriteTile->TopOffset << FRACBITS;
-	dc_texturemid = topoff + (zpos - ViewPos.Z) / yscale;
+	yscale = decal->ScaleY;
+	dc_texturemid = WallSpriteTile->TopOffset + (zpos - ViewPos.Z) / yscale;
 
 	// Clip sprite to drawseg
 	x1 = MAX<int>(clipper->x1, x1);
@@ -3194,7 +3188,7 @@ static void R_RenderDecal (side_t *wall, DBaseDecal *decal, drawseg_t *clipper,
 		goto done;
 	}
 
-	PrepWall (swall, lwall, WallSpriteTile->GetWidth() << FRACBITS, x1, x2);
+	PrepWall (swall, lwall, WallSpriteTile->GetWidth(), x1, x2);
 
 	if (flipx)
 	{
@@ -3242,7 +3236,7 @@ static void R_RenderDecal (side_t *wall, DBaseDecal *decal, drawseg_t *clipper,
 	}
 
 	// rw_offset is used as the texture's vertical scale
-	rw_offset = SafeDivScale30(1, yscale);
+	rw_offset = FLOAT2FIXED(1 / yscale);
 
 	do
 	{
diff --git a/src/r_things.cpp b/src/r_things.cpp
index 42308a9e7..3cda3cb91 100644
--- a/src/r_things.cpp
+++ b/src/r_things.cpp
@@ -632,9 +632,8 @@ void R_DrawWallSprite(vissprite_t *spr)
 
 void R_WallSpriteColumn (void (*drawfunc)(const BYTE *column, const FTexture::Span *spans))
 {
-	unsigned int texturecolumn = lwall[dc_x] >> FRACBITS;
-	dc_iscale = MulScale16 (swall[dc_x], rw_offset);
-	spryscale = SafeDivScale32 (1, dc_iscale);
+	dc_iscale = MulScale16 (swall[dc_x], rw_offset/4);
+	spryscale = 65536.0 / dc_iscale;
 	if (sprflipvert)
 		sprtopscreen = CenterY + dc_texturemid * spryscale;
 	else
@@ -642,7 +641,7 @@ void R_WallSpriteColumn (void (*drawfunc)(const BYTE *column, const FTexture::Sp
 
 	const BYTE *column;
 	const FTexture::Span *spans;
-	column = WallSpriteTile->GetColumn (texturecolumn, &spans);
+	column = WallSpriteTile->GetColumn (lwall[dc_x] >> FRACBITS, &spans);
 	dc_texturefrac = 0;
 	drawfunc (column, spans);
 	rw_light += rw_lightstep;