From 67334bfa2bc26c641e1a9705db901af1b4889743 Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@zdoom.fake>
Date: Sat, 4 Apr 2015 12:35:10 +0200
Subject: [PATCH] - calculate weapon positions fully in floating point to avoid
 roundoff errors. - In order to get reliable results the empty border around
 scaled sprites must be the same scale as the sprite (i.e. 2 pixels for 2x
 scale and 4 pixels for 4x scale.)

---
 src/gl/scene/gl_weapon.cpp      | 14 +++++++------
 src/gl/textures/gl_material.cpp | 35 +++++++++++++++++++++++----------
 2 files changed, 33 insertions(+), 16 deletions(-)

diff --git a/src/gl/scene/gl_weapon.cpp b/src/gl/scene/gl_weapon.cpp
index 42397166ba..89a5e1efb0 100644
--- a/src/gl/scene/gl_weapon.cpp
+++ b/src/gl/scene/gl_weapon.cpp
@@ -79,7 +79,8 @@ void FGLRenderer::DrawPSprite (player_t * player,pspdef_t *psp,fixed_t sx, fixed
 	int				x1,y1,x2,y2;
 	float			scale;
 	fixed_t			scalex;
-	fixed_t			texturemid;// 4:3		16:9		16:10			17:10			5:4
+	float			ftexturemid;
+	                         // 4:3	     16:9          16:10         17:10           5:4
 	static fixed_t xratio[] = {FRACUNIT, FRACUNIT*3/4, FRACUNIT*5/6, FRACUNIT*40/51, FRACUNIT};
 	
 	// [BB] In the HUD model step we just render the model and break out. 
@@ -116,23 +117,24 @@ void FGLRenderer::DrawPSprite (player_t * player,pspdef_t *psp,fixed_t sx, fixed
 	x2+=viewwindowx;
 
 	// killough 12/98: fix psprite positioning problem
-	texturemid = (100<<FRACBITS) - (sy-(tex->GetScaledTopOffset()<<FRACBITS));
+	ftexturemid = 100.f - FIXED2FLOAT(sy) + tex->GetScaledTopOffsetFloat();
 
 	AWeapon * wi=player->ReadyWeapon;
 	if (wi && wi->YAdjust)
 	{
+		float fYAd = FIXED2FLOAT(wi->YAdjust);
 		if (screenblocks>=11)
 		{
-			texturemid -= wi->YAdjust;
+			ftexturemid -= fYAd;
 		}
 		else if (!st_scale)
 		{
-			texturemid -= FixedMul (StatusBar->GetDisplacement (), wi->YAdjust);
+			ftexturemid -= FIXED2FLOAT(StatusBar->GetDisplacement ()) * fYAd;
 		}
 	}
 
-	scale = ((SCREENHEIGHT*vw)/SCREENWIDTH) / 200.0f;    
-	y1 = viewwindowy + (vh >> 1) - (int)(((float)texturemid / (float)FRACUNIT) * scale);
+	scale =  (SCREENHEIGHT*vw)/ (SCREENWIDTH * 200.0f);    
+	y1 = viewwindowy + (vh >> 1) - (int)(ftexturemid * scale);
 	y2 = y1 + (int)((float)tex->TextureHeight() * scale) + 1;
 
 	if (!mirror)
diff --git a/src/gl/textures/gl_material.cpp b/src/gl/textures/gl_material.cpp
index eca7c66c54..c5eb7fc34e 100644
--- a/src/gl/textures/gl_material.cpp
+++ b/src/gl/textures/gl_material.cpp
@@ -460,17 +460,25 @@ FMaterial::FMaterial(FTexture * tx, bool expanded)
 	if (expanded)
 	{
 		// a little adjustment to make sprites look better with texture filtering:
-		// create a 1 pixel wide empty frame around them.
-		mWidth+=2;
-		mHeight+=2;
-		mLeftOffset+=1;
-		mTopOffset+=1;
-		mRenderWidth = mRenderWidth * mWidth / (mWidth-2);
-		mRenderHeight = mRenderHeight * mHeight / (mHeight-2);
-
+		// create a 1 pixel wide empty frame around them. The frame must be the same size as the texture scale so that
+		// position calculations remain scale independent.
 		int trim[4];
+		bool trimmed = TrimBorders(trim);	// get the trim size before adding the empty frame
 
-		if (TrimBorders(trim))
+		int intscaleX = MAX(1, tex->xScale >> FRACBITS);
+		int intscaleY = MAX(1, tex->yScale >> FRACBITS);
+		int oldwidth = mWidth;
+		int oldheight = mHeight;
+
+		mWidth+=2*intscaleX;
+		mHeight+=2*intscaleY;
+		mLeftOffset+=intscaleX;
+		mTopOffset+=intscaleY;
+		mRenderWidth = mRenderWidth * mWidth / oldwidth;
+		mRenderHeight = mRenderHeight * mHeight / oldheight;
+
+		/* NOTE: This formula is a bit broken and needs fixing.*/
+		if (trimmed)
 		{
 			mSpriteRect.left = -(mLeftOffset - trim[0]) / FIXED2FLOAT(tx->xScale);
 			mSpriteRect.top = -(mTopOffset - trim[1]) / FIXED2FLOAT(tx->yScale);
@@ -482,6 +490,13 @@ FMaterial::FMaterial(FTexture * tx, bool expanded)
 			mSpriteU[1] *= (trim[0]+trim[2]+2) / (float)mWidth; 
 			mSpriteV[1] *= (trim[1]+trim[3]+2) / (float)mHeight; 
 		}
+		else
+		{
+			mSpriteRect.left = -mLeftOffset / FIXED2FLOAT(tx->xScale);
+			mSpriteRect.top = -mTopOffset / FIXED2FLOAT(tx->yScale);
+			mSpriteRect.width = mWidth / FIXED2FLOAT(tx->xScale);
+			mSpriteRect.height = mHeight / FIXED2FLOAT(tx->yScale);
+		}
 	}
 
 	mTextureLayers.ShrinkToFit();
@@ -761,7 +776,7 @@ FMaterial * FMaterial::ValidateTexture(FTexture * tex, bool expand)
 		FMaterial *gltex = tex->gl_info.Material[expand];
 		if (gltex == NULL) 
 		{
-			if (tex->bWarped || tex->bHasCanvas || tex->gl_info.shaderindex >= FIRST_USER_SHADER)
+			if (tex->bWarped || tex->bHasCanvas || tex->gl_info.shaderindex >= FIRST_USER_SHADER)// || tex->xScale != FRACUNIT && tex->yScale != FRACUNIT)
 			{
 				expand = false;
 			}