OpenGL Flipped Patch Drawing

V_FLIP in OpenGL.

src/hardware/hw_draw.c

@@ -179,17 +179,37 @@ void HWR_DrawFixedPatch(GLPatch_t *gpatch, fixed_t x, fixed_t y, fixed_t pscale,
 	if (option & V_NOSCALESTART)
 		sdupx = sdupy = 2.0f;
 
-	v[0].x = v[3].x = (cx*sdupx-gpatch->leftoffset*pdupx)/vid.width - 1;
-	v[2].x = v[1].x = (cx*sdupx+(gpatch->width-gpatch->leftoffset)*pdupx)/vid.width - 1;
-	v[0].y = v[1].y = 1-(cy*sdupy-gpatch->topoffset*pdupy)/vid.height;
-	v[2].y = v[3].y = 1-(cy*sdupy+(gpatch->height-gpatch->topoffset)*pdupy)/vid.height;
+	if (option & V_FLIP) // Need to flip both this and sow
+	{
+		v[0].x = v[3].x = (cx*sdupx-(gpatch->width-gpatch->leftoffset)*pdupx)/vid.width - 1;
+		v[2].x = v[1].x = (cx*sdupx+gpatch->leftoffset*pdupx)/vid.width - 1;
+		v[0].y = v[1].y = 1-(cy*sdupy-gpatch->topoffset*pdupy)/vid.height;
+		v[2].y = v[3].y = 1-(cy*sdupy+(gpatch->height-gpatch->topoffset)*pdupy)/vid.height;
+	}
+	else
+	{
+		v[0].x = v[3].x = (cx*sdupx-gpatch->leftoffset*pdupx)/vid.width - 1;
+		v[2].x = v[1].x = (cx*sdupx+(gpatch->width-gpatch->leftoffset)*pdupx)/vid.width - 1;
+		v[0].y = v[1].y = 1-(cy*sdupy-gpatch->topoffset*pdupy)/vid.height;
+		v[2].y = v[3].y = 1-(cy*sdupy+(gpatch->height-gpatch->topoffset)*pdupy)/vid.height;
+	}
 
 	v[0].z = v[1].z = v[2].z = v[3].z = 1.0f;
 
-	v[0].sow = v[3].sow = 0.0f;
-	v[2].sow = v[1].sow = gpatch->max_s;
-	v[0].tow = v[1].tow = 0.0f;
-	v[2].tow = v[3].tow = gpatch->max_t;
+	if (option & V_FLIP)
+	{
+		v[0].sow = v[3].sow = gpatch->max_s;
+		v[2].sow = v[1].sow = 0.0f;
+		v[0].tow = v[1].tow = 0.0f;
+		v[2].tow = v[3].tow = gpatch->max_t;
+	}
+	else
+	{
+		v[0].sow = v[3].sow = 0.0f;
+		v[2].sow = v[1].sow = gpatch->max_s;
+		v[0].tow = v[1].tow = 0.0f;
+		v[2].tow = v[3].tow = gpatch->max_t;
+	}
 
 	flags = BLENDMODE|PF_Clip|PF_NoZClip|PF_NoDepthTest;