implement/fix clipping during rendering of light

src/landscape/fow/C4FoWLight.cpp

@@ -5,6 +5,8 @@
 #include "C4FoWBeamTriangle.h"
 #include "C4FoWDrawStrategy.h"
 
+#include <vector>
+
 C4FoWLight::C4FoWLight(C4Object *pObj)
 	: iX(fixtoi(pObj->fix_x)),
 	  iY(fixtoi(pObj->fix_y)),
@@ -13,23 +15,24 @@ C4FoWLight::C4FoWLight(C4Object *pObj)
 	  iSize(20),
 	  pNext(NULL),
 	  pObj(pObj),
-	  sectionUp(this, 0),
+	  sections(4)
-	  sectionLeft(this, 270),
-	  sectionDown(this, 180),
-	  sectionRight(this, 90)
 {
+	sections[0] = new C4FoWLightSection(this,0);
+	sections[1] = new C4FoWLightSection(this,90);
+	sections[2] = new C4FoWLightSection(this,180);
+	sections[3] = new C4FoWLightSection(this,270);
 }
 
 C4FoWLight::~C4FoWLight()
 {
+	for( int i = 0; i < sections.size(); ++i )
+		delete sections[i];
 }
 
 void C4FoWLight::Invalidate(C4Rect r)
 {
-	sectionUp.Invalidate(r);
+	for( int i = 0; i < sections.size(); ++i )
-	sectionDown.Invalidate(r);
+		sections[i]->Invalidate(r);
-	sectionLeft.Invalidate(r);
-	sectionRight.Invalidate(r);
 }
 
 void C4FoWLight::SetReach(int32_t iReach2, int32_t iFadeout2)
@@ -43,52 +46,53 @@ void C4FoWLight::SetReach(int32_t iReach2, int32_t iFadeout2)
 	if (iReach2 < iReach)
 	{
 		iReach = iReach2;
-		sectionUp.Prune(iReach);
+		for( int i = 0; i < sections.size(); ++i )
-		sectionDown.Prune(iReach);
+			sections[i]->Prune(iReach);
-		sectionLeft.Prune(iReach);
-		sectionRight.Prune(iReach);
 
 	} else {
 
 		// Reach increased? Dirty beams that might get longer now
 		iReach = iReach2;
-		sectionUp.Dirty(iReach);
+		for( int i = 0; i < sections.size(); ++i )
-		sectionDown.Dirty(iReach);
+			sections[i]->Dirty(iReach);
-		sectionLeft.Dirty(iReach);
-		sectionRight.Dirty(iReach);
 	}
 }
 
 void C4FoWLight::Update(C4Rect Rec)
 {
-
 	// Update position from object. Clear if we moved in any way
 	int32_t iNX = fixtoi(pObj->fix_x), iNY = fixtoi(pObj->fix_y);
 	if (iNX != iX || iNY != iY)
 	{
-		sectionUp.Prune(0);
+		for( int i = 0; i < sections.size(); ++i )
-		sectionDown.Prune(0);
+			sections[i]->Prune(0);
-		sectionLeft.Prune(0);
-		sectionRight.Prune(0);
 		iX = iNX; iY = iNY;
 	}
 
-	sectionUp.Update(Rec);
+	for( int i = 0; i < sections.size(); ++i )
-	sectionDown.Update(Rec);
+		sections[i]->Update(Rec);
-	sectionLeft.Update(Rec);
-	sectionRight.Update(Rec);
 }
 
 void C4FoWLight::Render(C4FoWRegion *region, const C4TargetFacet *onScreen)
 {
 	std::list<C4FoWBeamTriangle> triangles;
-	triangles.splice(triangles.end(), sectionUp.CalculateTriangles(region));
-	triangles.splice(triangles.end(), sectionRight.CalculateTriangles(region));
-	triangles.splice(triangles.end(), sectionDown.CalculateTriangles(region));
-	triangles.splice(triangles.end(), sectionLeft.CalculateTriangles(region));
 
-	CalculateIntermediateFadeTriangles(triangles);
+	bool clip = false;
 	
+	for( int i = 0; i < sections.size(); ++i )
+	{
+		std::list<C4FoWBeamTriangle> &sectionTriangles = sections[i]->CalculateTriangles(region);
+
+		// if the triangles of one section are clipped completely, the neighbouring triangles
+		// must be marked as clipped
+		if(!triangles.empty()) triangles.rbegin()->clipRight |= clip;
+		if(!sectionTriangles.empty()) sectionTriangles.begin()->clipLeft |= clip;
+
+		clip = sectionTriangles.empty();
+		triangles.splice(triangles.end(), sectionTriangles);
+	}
+	CalculateIntermediateFadeTriangles(triangles);
+
 	// Here's the master plan for updating the lights texture. We
 	// want to add intensity (R channel) as well as the normal (GB channels).
 	// Normals are obviously meant to be though of as signed, though,
@@ -184,7 +188,9 @@ void C4FoWLight::DrawFan(C4FoWDrawStrategy* pen, std::list<C4FoWBeamTriangle> &t
 		C4FoWBeamTriangle &tri = *it, &nextTri = *nextIt; // just for convenience
 
 		pen->DrawLightVertex(tri.fanLX, tri.fanLY);	
-		pen->DrawLightVertex(tri.fanRX, tri.fanRY);
+
+		if(nextTri.fanLX != tri.fanRX || nextTri.fanLY != tri.fanRY)
+			pen->DrawLightVertex(tri.fanRX, tri.fanRY);
 	}
 	pen->EndFan();
 }

src/landscape/fow/C4FoWLight.h

@@ -7,6 +7,8 @@
 #include "C4FoWLightSection.h"
 #include "C4Rect.h"
 
+#include <vector>
+
 /** This class represents one light source. A light source has an associated object with which the light source moves
     and one light section that handles the light beams for each direction (up, down, left, right).
 
@@ -27,10 +29,7 @@ private:
 	C4FoWLight *pNext;
 	C4Object *pObj; // Associated object
 
-	C4FoWLightSection sectionUp;
+	std::vector<C4FoWLightSection*> sections;
-	C4FoWLightSection sectionLeft;
-	C4FoWLightSection sectionDown;
-	C4FoWLightSection sectionRight;
 
 public:
 	int32_t getX() const { return iX; }

src/landscape/fow/C4FoWLightSection.cpp

@@ -397,7 +397,7 @@ void C4FoWLightSection::Invalidate(C4Rect r)
 
 }
 
-int32_t C4FoWLightSection::FindBeamsClipped(const C4Rect &rect, C4FoWBeam *&firstBeam, C4FoWBeam *&lastBeam)
+int32_t C4FoWLightSection::FindBeamsClipped(const C4Rect &rect, C4FoWBeam *&firstBeam, C4FoWBeam *&endBeam)
 {
 	if(rect.y + rect.Hgt < 0) return 0;
 
@@ -417,7 +417,7 @@ int32_t C4FoWLightSection::FindBeamsClipped(const C4Rect &rect, C4FoWBeam *&firs
 		beam = beam->getNext();
 		beamCount++;
 	}
-	lastBeam = beam;
+	endBeam = beam;
 
 	return beamCount;
 }
@@ -426,10 +426,14 @@ std::list<C4FoWBeamTriangle> C4FoWLightSection::CalculateTriangles(C4FoWRegion *
 {
 	C4FoWBeam *startBeam = NULL, *endBeam = NULL;
 	int32_t beamCount = FindBeamsClipped(rtransRect(region->getRegion()), startBeam, endBeam);
-	// no beams inside the rectangle? Good, nothing to render 
 	std::list<C4FoWBeamTriangle> result;
+
+	// no beams inside the rectangle? Good, nothing to render 
 	if(!beamCount) return result;
 
+	bool isStartClipped = startBeam != pBeams;
+	bool isEndClipped = !!endBeam;
+
 	C4FoWBeam *beam = startBeam;
 	for (int32_t i = 0; i < beamCount; i++, beam = beam->getNext())
 	{
@@ -438,9 +442,15 @@ std::list<C4FoWBeamTriangle> C4FoWLightSection::CalculateTriangles(C4FoWRegion *
 		tri.fanLY = float(beam->getLeftEndY());
 		tri.fanRX = beam->getRightEndXf();
 		tri.fanRY = float(beam->getRightEndY());
-		tri.clipLeft = false; // TODO Newton: pBeams.start != startBeam
+		if(i == 0 && isStartClipped)
-		tri.clipRight = false; // TODO Newton: pBeams.end != endBeam
+			tri.clipLeft = true;
-		result.push_back(tri);
+		if(i == beamCount - 1 && isEndClipped)
+		{
+			tri.clipRight = true;
+		}
+
+		if(tri.fanLX != tri.fanRX || tri.fanLY != tri.fanRY)
+			result.push_back(tri);
 	}
 
 	// Phase 1: Project lower point so it lies on a line with outer left/right

src/landscape/fow/C4FoWLightSection.h

@@ -105,8 +105,9 @@ private:
 	C4FoWBeam *FindBeamLeftOf(int32_t x, int32_t y);
 
 	/** Find beams that go through the given rectangle. Returns the number of beams that are in the rectangle and makes
-	    pFirst and pLast point to the first and the last beam of these */
+	    firstBeam point to the first and endBeam point to the beam after the last of these. Thus, endBeam is NULL if 
-	int32_t FindBeamsClipped(const C4Rect &rect, C4FoWBeam *&firstBeam, C4FoWBeam *&lastBeam);
+		no beams were clipped at the end. */
+	int32_t FindBeamsClipped(const C4Rect &rect, C4FoWBeam *&firstBeam, C4FoWBeam *&endBeam);
 };