From 70fd6d20bf7cc1cbd1dc2823a3cc485ded852957 Mon Sep 17 00:00:00 2001
From: Armin Burgmeier <armin@arbur.net>
Date: Sat, 17 Oct 2015 17:35:33 -0400
Subject: [PATCH] Keep parallax objects fixed on full map screenshots (#1042)

---
 src/game/C4GraphicsSystem.cpp |  2 +-
 src/graphics/C4FacetEx.cpp    | 12 ++++++++++--
 src/graphics/C4FacetEx.h      | 17 +++++++++++++++--
 src/object/C4Object.cpp       |  4 ++--
 4 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/src/game/C4GraphicsSystem.cpp b/src/game/C4GraphicsSystem.cpp
index 126c130ee..33cae7c73 100644
--- a/src/game/C4GraphicsSystem.cpp
+++ b/src/game/C4GraphicsSystem.cpp
@@ -265,7 +265,7 @@ bool C4GraphicsSystem::DoSaveScreenshot(bool fSaveAll, const char *szFilename, f
 				if (iX+bkWdt2>lWdt) bkWdt2-=iX+bkWdt2-lWdt;
 				if (iY+bkHgt2>lHgt) bkHgt2-=iY+bkHgt2-lHgt;
 				// update facet
-				bkFct.Set(FullScreen.pSurface, 0, 0, ceil(float(bkWdt2)/zoom), ceil(float(bkHgt2)/zoom), iX/zoom, iY/zoom, zoom);
+				bkFct.Set(FullScreen.pSurface, 0, 0, ceil(float(bkWdt2)/zoom), ceil(float(bkHgt2)/zoom), iX/zoom, iY/zoom, zoom, 0, 0);
 				// draw there
 				pVP->Draw(bkFct, false);
 				// render
diff --git a/src/graphics/C4FacetEx.cpp b/src/graphics/C4FacetEx.cpp
index 319efcdf2..73d998e6e 100644
--- a/src/graphics/C4FacetEx.cpp
+++ b/src/graphics/C4FacetEx.cpp
@@ -23,20 +23,28 @@
 #include <C4Rect.h>
 #include <C4Group.h>
 
-
 void C4TargetFacet::Set(C4Surface * nsfc, float nx, float ny, float nwdt, float nhgt, float ntx, float nty, float Zoom)
+{
+	Set(nsfc, nx, ny, nwdt, nhgt, ntx, nty, Zoom, ntx, nty);
+}
+
+void C4TargetFacet::Set(C4Surface * nsfc, float nx, float ny, float nwdt, float nhgt, float ntx, float nty, float Zoom, float prx, float pry)
 {
 	C4Facet::Set(nsfc, nx, ny, nwdt, nhgt);
 	TargetX = ntx; TargetY = nty; this->Zoom = Zoom;
+	ParRefX = prx; ParRefY = pry;
 }
 
 void C4TargetFacet::Set(C4Surface * nsfc, const C4Rect & r, float ntx, float nty, float Zoom)
 {
 	Set(nsfc, r.x, r.y, r.Wdt, r.Hgt, ntx, nty, Zoom);
 }
+
 void C4TargetFacet::SetRect(C4TargetRect &rSrc)
 {
-	X=rSrc.x; Y=rSrc.y; Wdt=rSrc.Wdt; Hgt=rSrc.Hgt; TargetX=rSrc.tx; TargetY=rSrc.ty;
+	X=rSrc.x; Y=rSrc.y; Wdt=rSrc.Wdt; Hgt=rSrc.Hgt;
+	TargetX=rSrc.tx; TargetY=rSrc.ty;
+	ParRefX=rSrc.tx; TargetY=rSrc.ty;
 }
 
 // ------------------------
diff --git a/src/graphics/C4FacetEx.h b/src/graphics/C4FacetEx.h
index 2868436ab..4fac07000 100644
--- a/src/graphics/C4FacetEx.h
+++ b/src/graphics/C4FacetEx.h
@@ -34,14 +34,27 @@ public:
 	~C4TargetFacet() { }
 public:
 	float TargetX,TargetY,Zoom;
+
+	// Reference values for parallax computations. This is similar to
+	// a scrolling position. In most cases these are the same as TargetX
+	// and TargetY, however for full map screenshots, which are composed
+	// of several individual screenshots, these are kept fixed while
+	// TargetX/TargetY are varied to cover the full map. This prevents
+	// duplicate parallax objects in fullscreen map screenshots. If
+	// TargetX/TargetY are different from ParRefX/ParRefY it can be thought
+	// of as drawing only a part of a window/viewport at a given fixed
+	// scroll position.
+	// See bug #1042.
+	float ParRefX, ParRefY;
 public:
-	void Default() { TargetX=TargetY=0; Zoom=1; C4Facet::Default(); }
+	void Default() { TargetX=TargetY=0; Zoom=1; ParRefX=ParRefY=0; C4Facet::Default(); }
 	void Clear() { Surface=NULL; }
 
-	void Set(const C4Facet &cpy) { TargetX=TargetY=0; Zoom=1; C4Facet::Set(cpy); }
+	void Set(const C4Facet &cpy) { TargetX=TargetY=0; Zoom=1; ParRefX=ParRefY=0; C4Facet::Set(cpy); }
 	void Set(const C4TargetFacet &cpy) { *this = cpy; }
 	void Set(class C4Surface *nsfc, float nx, float ny, float nwdt, float nhgt, float ntx=0, float nty=0, float Zoom=1);
 	void Set(class C4Surface *nsfc, const C4Rect & r, float ntx=0, float nty=0, float Zoom=1);
+	void Set(class C4Surface *nsfc, float nx, float ny, float nwdt, float nhgt, float ntx, float nty, float Zoom, float prx, float pry);
 
 public:
 	C4TargetFacet &operator = (const C4Facet& rhs)
diff --git a/src/object/C4Object.cpp b/src/object/C4Object.cpp
index ed82a2b14..04105f78f 100644
--- a/src/object/C4Object.cpp
+++ b/src/object/C4Object.cpp
@@ -4478,8 +4478,8 @@ bool C4Object::GetDrawPosition(const C4TargetFacet & cgo, float objx, float objy
 	if (resultzoom <= 0 || resultzoom > 100) // FIXME: optimize treshhold
 		return false;
 
-	float rx = ((1 - parx) * targetx) * resultzoom + objx / (parx + zoom - parx * zoom);
-	float ry = ((1 - pary) * targety) * resultzoom + objy / (pary + zoom - pary * zoom);
+	float rx = ((1 - parx) * cgo.ParRefX) * resultzoom + objx / (parx + zoom - parx * zoom);
+	float ry = ((1 - pary) * cgo.ParRefY) * resultzoom + objy / (pary + zoom - pary * zoom);
 
 	// Step 2: convert to screen coordinates
 	if(parx == 0 && fix_x < 0)