fix(heightmap): Properly draw larger terrain area on low camera pitch (#2677)

Author: xezon

Core/GameEngine/Include/GameClient/View.h

@@ -52,6 +52,7 @@ enum FilterModes CPP_11(: Int);
 
 // ------------------------------------------------------------------------------------------------
 constexpr const Real ViewDefaultPitchRadians = DEG_TO_RADF(37.5f);
+constexpr const Real ViewDefaultLowPitchRadians = DEG_TO_RADF(37.0f);
 constexpr const Real ViewDefaultYawRadians = DEG_TO_RADF(0.0f);
 constexpr const Real ViewDefaultMaxHeightAboveTerrain = 310.0f;
 

Core/GameEngineDevice/Include/W3DDevice/GameClient/BaseHeightMap.h

@@ -119,7 +119,7 @@ class BaseHeightMapRenderObjClass : public RenderObjClass, public DX8_CleanupHoo
 	///allocate resources needed to render heightmap
 	virtual int initHeightData(Int width, Int height, WorldHeightMap *pMap, RefRenderObjListIterator *pLightsIterator, Bool updateExtraPassTiles=TRUE);
 	virtual Int freeMapResources();	///< free resources used to render heightmap
-	virtual void updateCenter(CameraClass *camera, RefRenderObjListIterator *pLightsIterator);
+	virtual void updateCenter(CameraClass *camera, const Vector3 *cameraPivot, RefRenderObjListIterator *pLightsIterator);
  	virtual void adjustTerrainLOD(Int adj);
 	virtual void doPartialUpdate(const IRegion2D &partialRange, WorldHeightMap *htMap, RefRenderObjListIterator *pLightsIterator) = 0;
 	virtual void staticLightingChanged();

Core/GameEngineDevice/Include/W3DDevice/GameClient/FlatHeightMap.h

@@ -66,7 +66,7 @@ class FlatHeightMapRenderObjClass : public BaseHeightMapRenderObjClass
 	///allocate resources needed to render heightmap
 	virtual int initHeightData(Int width, Int height, WorldHeightMap *pMap, RefRenderObjListIterator *pLightsIterator,Bool updateExtraPassTiles=TRUE) override;
 	virtual Int freeMapResources() override;	///< free resources used to render heightmap
-	virtual void updateCenter(CameraClass *camera, RefRenderObjListIterator *pLightsIterator) override;
+	virtual void updateCenter(CameraClass *camera, const Vector3 *cameraPivot, RefRenderObjListIterator *pLightsIterator) override;
  	virtual void adjustTerrainLOD(Int adj) override;
 	virtual void reset() override;
 	virtual void oversizeTerrain(Int tilesToOversize) override; ///< Oversize the visible terrain area.

Core/GameEngineDevice/Include/W3DDevice/GameClient/HeightMap.h

@@ -73,7 +73,7 @@ class HeightMapRenderObjClass : public BaseHeightMapRenderObjClass
 	///allocate resources needed to render heightmap
 	virtual int initHeightData(Int width, Int height, WorldHeightMap *pMap, RefRenderObjListIterator *pLightsIterator, Bool updateExtraPassTiles=TRUE) override;
 	virtual Int freeMapResources() override;	///< free resources used to render heightmap
-	virtual void updateCenter(CameraClass *camera, RefRenderObjListIterator *pLightsIterator) override;
+	virtual void updateCenter(CameraClass *camera, const Vector3 *cameraPivot, RefRenderObjListIterator *pLightsIterator) override;
 
 	virtual void staticLightingChanged() override;
 	virtual	void adjustTerrainLOD(Int adj) override;

Core/GameEngineDevice/Include/W3DDevice/GameClient/WorldHeightMap.h

@@ -125,6 +125,8 @@ class WorldHeightMap : public RefCountClass,
 		NORMAL_DRAW_HEIGHT = 1 + 4*VERTEX_BUFFER_TILE_LENGTH,
 		STRETCH_DRAW_WIDTH = 1 + 2*VERTEX_BUFFER_TILE_LENGTH,
 		STRETCH_DRAW_HEIGHT = 1 + 2*VERTEX_BUFFER_TILE_LENGTH,
+		LOW_ANGLE_DRAW_WIDTH = 1 + (NORMAL_DRAW_WIDTH-1) * 2,
+		LOW_ANGLE_DRAW_HEIGHT = 1 + (NORMAL_DRAW_HEIGHT-1) * 2,
 	};
 
 protected:

Core/GameEngineDevice/Source/W3DDevice/GameClient/BaseHeightMap.cpp

@@ -1318,18 +1318,6 @@ Bool BaseHeightMapRenderObjClass::evaluateAsVisibleCliff(Int xIndex, Int yIndex,
 	return anyImpassable;
 }
 
-//=============================================================================
-// BaseHeightMapRenderObjClass::oversizeTerrain
-//=============================================================================
-/** Sets the terrain oversize amount. */
-//=============================================================================
-void BaseHeightMapRenderObjClass::oversizeTerrain(Int tilesToOversize)
-{
-	// Not needed with flat version. [3/20/2003]
-}
-
-
-
 //=============================================================================
 // BaseHeightMapRenderObjClass::Get_Obj_Space_Bounding_Sphere
 //=============================================================================
@@ -2394,7 +2382,7 @@ rendered portion of the terrain.  Only a 96x96 section is rendered at any time,
 even though maps can be up to 1024x1024.  This function determines which subset
 is rendered. */
 //=============================================================================
-void BaseHeightMapRenderObjClass::updateCenter(CameraClass *camera , RefRenderObjListIterator *pLightsIterator)
+void BaseHeightMapRenderObjClass::updateCenter(CameraClass *camera, const Vector3 *cameraPivot, RefRenderObjListIterator *pLightsIterator)
 {
 	if (m_map==nullptr) {
 		return;

Core/GameEngineDevice/Source/W3DDevice/GameClient/FlatHeightMap.cpp

@@ -407,13 +407,13 @@ rendered portion of the terrain.  Only a 96x96 section is rendered at any time,
 even though maps can be up to 1024x1024.  This function determines which subset
 is rendered. */
 //=============================================================================
-void FlatHeightMapRenderObjClass::updateCenter(CameraClass *camera , RefRenderObjListIterator *pLightsIterator)
+void FlatHeightMapRenderObjClass::updateCenter(CameraClass *camera, const Vector3 *cameraPivot, RefRenderObjListIterator *pLightsIterator)
 {
 #ifdef DO_UNIT_TIMINGS
 #pragma MESSAGE("*** WARNING *** DOING DO_UNIT_TIMINGS!!!!")
 	return;
 #endif
-	BaseHeightMapRenderObjClass::updateCenter(camera, pLightsIterator);
+	BaseHeightMapRenderObjClass::updateCenter(camera, cameraPivot, pLightsIterator);
 	m_needFullUpdate = false;
 	Int i, j;
 	Int culled = 0;

Core/GameEngineDevice/Source/W3DDevice/GameClient/HeightMap.cpp

@@ -1658,11 +1658,10 @@ static void calcVis(const FrustumClass & frustum, WorldHeightMap *pMap, Int minX
 //=============================================================================
 /** Updates the positioning of the drawn portion of the height map in the
 heightmap.  As the view slides around, this determines what is the actually
-rendered portion of the terrain.  Only a 96x96 section is rendered at any time,
-even though maps can be up to 1024x1024.  This function determines which subset
-is rendered. */
+rendered portion of the terrain. Only a small section is rendered at any time.
+*/
 //=============================================================================
-void HeightMapRenderObjClass::updateCenter(CameraClass *camera , RefRenderObjListIterator *pLightsIterator)
+void HeightMapRenderObjClass::updateCenter(CameraClass *camera, const Vector3 *cameraPivot, RefRenderObjListIterator *pLightsIterator)
 {
 	if (m_map==nullptr) {
 		return;
@@ -1673,105 +1672,127 @@ void HeightMapRenderObjClass::updateCenter(CameraClass *camera , RefRenderObjLis
 	if (m_vertexBufferTiles ==nullptr)
 		return;		//did not initialize resources yet.
 
-	BaseHeightMapRenderObjClass::updateCenter(camera, pLightsIterator);
+	BaseHeightMapRenderObjClass::updateCenter(camera, cameraPivot, pLightsIterator);
 
 	if (m_x >= m_map->getXExtent() && m_y >= m_map->getYExtent())
   {
 		return; // no need to center.
 	}
 
+	const Real cameraPitch = WWMath::Asin(fabsf(camera->Get_Forward_Dir().Z));
 	Int newOrgX;
 	Int newOrgY;
 
-	// determine the ray corresponding to the camera and distance to projection plane
-	Matrix3D camera_matrix = camera->Get_Transform();
-
-	Vector3 camera_location  = camera->Get_Position();
-
-	Vector3 rayLocation;
-	Vector3 rayDirection;
-	Vector3 rayDirectionPt;
-	// the projected ray has the same origin as the camera
-	rayLocation = camera_location;
-	// determine the location of the screen coordinate in camera-model space
-	const ViewportClass &viewport = camera->Get_Viewport();
-	Int i, j, minHt;
-
-	Real intersectionZ;
-	minHt = m_map->getMaxHeightValue();
-	for (j=0; j<m_y; j+=4) {
-		for (i=0; i<m_x; i+=4) {
-			Short cur = m_map->getDisplayHeight(i,j);
-			if (cur<minHt) minHt = cur;
+	if (cameraPitch > ViewDefaultLowPitchRadians)
+	{
+		// TheSuperHackers @info This is the original code to determine the center position for the visible terrain area.
+		// It is relatively expensive and breaks when the frustum planes can no longer intersect with the terrain at low camera
+		// pitch or when the camera is too far from the terrain, but it is very accurate when the camera is close to the
+		// terrain. For now, we prefer to keep this code for the original camera pitch and above.
+
+		// determine the ray corresponding to the camera and distance to projection plane
+		const Matrix3D& camera_matrix = camera->Get_Transform();
+		Vector3 camera_location  = camera->Get_Position();
+		Vector3 rayLocation;
+		Vector3 rayDirection;
+		Vector3 rayDirectionPt;
+		// the projected ray has the same origin as the camera
+		rayLocation = camera_location;
+		// determine the location of the screen coordinate in camera-model space
+		const ViewportClass &viewport = camera->Get_Viewport();
+		Int i, j, minHt;
+
+		Real intersectionZ;
+		minHt = m_map->getMaxHeightValue();
+		for (j=0; j<m_y; j+=4) {
+			for (i=0; i<m_x; i+=4) {
+				Short cur = m_map->getDisplayHeight(i,j);
+				if (cur<minHt) minHt = cur;
+			}
 		}
-	}
-	intersectionZ = (float)minHt;
-//	float aspect = camera->Get_Aspect_Ratio();
-
-	Vector2 min,max;
-	camera->Get_View_Plane(min,max);
-	float xscale = (max.X - min.X);
-	float yscale = (max.Y - min.Y);
-
-	float zmod = -1.0; // Scene->vpd; // Note: view plane distance is now always 1.0 from the camera
-	float minX = 200000;
-	float maxX = -minX;
-	float minY = 200000;
-	float maxY = -minY;
-	for (i=0; i<2; i++) {
-		for (j=0; j<2; j++) {
-			float xmod = (-i + 0.5 + viewport.Min.X) * zmod * xscale;// / aspect;
-			float ymod = (j - 0.5 - viewport.Min.Y) * zmod * yscale;// * aspect;
-
-			// transform the screen coordinates by the camera's matrix into world coordinates.
-			float x = zmod * camera_matrix[0][2] + xmod * camera_matrix[0][0] + ymod * camera_matrix[0][1];
-			float y = zmod * camera_matrix[1][2] + xmod * camera_matrix[1][0] + ymod * camera_matrix[1][1];
-			float z = zmod * camera_matrix[2][2] + xmod * camera_matrix[2][0] + ymod * camera_matrix[2][1];
-
-			rayDirection.Set(x,y,z);
-			rayDirection.Normalize();
-			rayDirectionPt = rayLocation+rayDirection;
-
-			x = Vector3::Find_X_At_Z(intersectionZ, rayLocation, rayDirectionPt);
-			y = Vector3::Find_Y_At_Z(intersectionZ, rayLocation, rayDirectionPt);
-			if (x<minX) minX = x;
-			if (x>maxX) maxX = x;
-			if (y<minY) minY = y;
-			if (y>maxY) maxY = y;
+		intersectionZ = (float)minHt;
+	//	float aspect = camera->Get_Aspect_Ratio();
+
+		Vector2 min,max;
+		camera->Get_View_Plane(min,max);
+		float xscale = (max.X - min.X);
+		float yscale = (max.Y - min.Y);
+
+		float zmod = -1.0; // Scene->vpd; // Note: view plane distance is now always 1.0 from the camera
+		float minX = 200000;
+		float maxX = -minX;
+		float minY = 200000;
+		float maxY = -minY;
+		for (i=0; i<2; i++) {
+			for (j=0; j<2; j++) {
+				float xmod = (-i + 0.5 + viewport.Min.X) * zmod * xscale;// / aspect;
+				float ymod = (j - 0.5 - viewport.Min.Y) * zmod * yscale;// * aspect;
+
+				// transform the screen coordinates by the camera's matrix into world coordinates.
+				float x = zmod * camera_matrix[0][2] + xmod * camera_matrix[0][0] + ymod * camera_matrix[0][1];
+				float y = zmod * camera_matrix[1][2] + xmod * camera_matrix[1][0] + ymod * camera_matrix[1][1];
+				float z = zmod * camera_matrix[2][2] + xmod * camera_matrix[2][0] + ymod * camera_matrix[2][1];
+
+				rayDirection.Set(x,y,z);
+				rayDirection.Normalize();
+				rayDirectionPt = rayLocation+rayDirection;
+
+				x = Vector3::Find_X_At_Z(intersectionZ, rayLocation, rayDirectionPt);
+				y = Vector3::Find_Y_At_Z(intersectionZ, rayLocation, rayDirectionPt);
+				if (x<minX) minX = x;
+				if (x>maxX) maxX = x;
+				if (y<minY) minY = y;
+				if (y>maxY) maxY = y;
+			}
 		}
-	}
 
-	// convert back to cell indexes.
-	minX /= MAP_XY_FACTOR;
-	maxX /= MAP_XY_FACTOR;
-	minY /= MAP_XY_FACTOR;
-	maxY /= MAP_XY_FACTOR;
-
-	minX += m_map->getBorderSizeInline();
-	maxX += m_map->getBorderSizeInline();
-	minY += m_map->getBorderSizeInline();
-	maxY += m_map->getBorderSizeInline();
-
-	visMinX = m_map->getXExtent();
-	visMinY = m_map->getYExtent();
-	visMaxX = 0;
-	visMaxY = 0;
-
-	///< @todo find out why values go out of range
-	if (minX<0) minX=0;
-	if (minY<0) minY=0;
-	if (maxX > visMinX) maxX = visMinX;
-	if (maxY > visMinY) maxY = visMinY;
-
-	const FrustumClass & frustum = camera->Get_Frustum();
-	Int limit = (maxX-minX)/2;
-	if (limit > WIDE_STEP/2) {
-		limit=WIDE_STEP/2;
-	}
-	calcVis(frustum, m_map, minX-WIDE_STEP/2, minY-WIDE_STEP/2, maxX+WIDE_STEP/2, maxY+WIDE_STEP/2, limit);
+		// convert back to cell indexes.
+		minX /= MAP_XY_FACTOR;
+		maxX /= MAP_XY_FACTOR;
+		minY /= MAP_XY_FACTOR;
+		maxY /= MAP_XY_FACTOR;
+
+		minX += m_map->getBorderSizeInline();
+		maxX += m_map->getBorderSizeInline();
+		minY += m_map->getBorderSizeInline();
+		maxY += m_map->getBorderSizeInline();
+
+		visMinX = m_map->getXExtent();
+		visMinY = m_map->getYExtent();
+		visMaxX = 0;
+		visMaxY = 0;
+
+		///< @todo find out why values go out of range
+		if (minX<0) minX=0;
+		if (minY<0) minY=0;
+		if (maxX > visMinX) maxX = visMinX;
+		if (maxY > visMinY) maxY = visMinY;
+
+		const FrustumClass & frustum = camera->Get_Frustum();
+		Int limit = (maxX-minX)/2;
+		if (limit > WIDE_STEP/2) {
+			limit=WIDE_STEP/2;
+		}
+		calcVis(frustum, m_map, minX-WIDE_STEP/2, minY-WIDE_STEP/2, maxX+WIDE_STEP/2, maxY+WIDE_STEP/2, limit);
 
-	newOrgX = (visMaxX+visMinX)/2 - m_x/2.0;
-	newOrgY = (visMaxY+visMinY)/2 - m_y/2.0;
+		newOrgX = (visMaxX+visMinX)/2 - m_x/2;
+		newOrgY = (visMaxY+visMinY)/2 - m_y/2;
+	}
+	else
+	{
+		// TheSuperHackers @fix Very fast approximation. Works well for all camera pitches, but is less accurate
+		// than the original implementation. Using this method for higher camera pitch would  require to increase
+		// the normal draw width by at least one tile length.
+		const Real visibleTerrainEdgeLen = (m_x+m_y)/2 * MAP_XY_FACTOR;
+		const Real magicEdgeLenScale = 0.25f * visibleTerrainEdgeLen;
+		Vector3 viewDir = camera->Get_Forward_Dir();
+		Vector2 shiftPivot;
+		shiftPivot.X = viewDir.X * magicEdgeLenScale;
+		shiftPivot.Y = viewDir.Y * magicEdgeLenScale;
+
+		newOrgX = WWMath::Round((cameraPivot->X + shiftPivot.X)/MAP_XY_FACTOR) - m_x/2 + m_map->getBorderSizeInline();
+		newOrgY = WWMath::Round((cameraPivot->Y + shiftPivot.Y)/MAP_XY_FACTOR) - m_y/2 + m_map->getBorderSizeInline();
+	}
 
 	WorldHeightMap::DrawArea newDrawArea = m_map->createDrawArea(newOrgX, newOrgY);
 

Core/GameEngineDevice/Source/W3DDevice/GameClient/W3DView.cpp

@@ -3695,7 +3695,27 @@ void W3DView::updateTerrain()
 	DEBUG_ASSERTCRASH(TheTerrainRenderObject != nullptr, ("TheTerrainRenderObject is null"));
 
 	RefRenderObjListIterator *it = W3DDisplay::m_3DScene->createLightsIterator();
-	TheTerrainRenderObject->updateCenter(m_3DCamera, it);
+	const Vector3 cameraPivot(m_pos.x, m_pos.y, m_pos.z);
+	const Real cameraPitch = WWMath::Asin(fabsf(m_3DCamera->Get_Forward_Dir().Z));
+	Int drawWidth;
+	Int drawHeight;
+
+	if (cameraPitch > ViewDefaultLowPitchRadians)
+	{
+		drawWidth = WorldHeightMap::NORMAL_DRAW_WIDTH;
+		drawHeight = WorldHeightMap::NORMAL_DRAW_HEIGHT;
+	}
+	else
+	{
+		// TheSuperHackers @tweak xezon 31/12/2025 Increases visible terrain area when lowering the camera pitch.
+		// Note: The default camera pitch in Generals was 37.5, which we prefer to keep the normal draw size for.
+		drawWidth = WorldHeightMap::LOW_ANGLE_DRAW_WIDTH;
+		drawHeight = WorldHeightMap::LOW_ANGLE_DRAW_HEIGHT;
+	}
+
+	TheTerrainRenderObject->setTerrainDrawSize(drawWidth, drawHeight);
+	TheTerrainRenderObject->updateCenter(m_3DCamera, &cameraPivot, it);
+
 	if (it)
 	{
 		W3DDisplay::m_3DScene->destroyLightsIterator(it);

Generals/Code/Tools/WorldBuilder/src/wbview3d.cpp

@@ -1964,7 +1964,7 @@ void WbView3d::redraw()
 		++m_updateCount;
 		Int curTicks = GetTickCount();
 		RefRenderObjListIterator lightListIt(&m_lightList);
-		m_heightMapRenderObj->updateCenter(m_camera, &lightListIt);
+		m_heightMapRenderObj->updateCenter(m_camera, &m_cameraTarget, &lightListIt);
 		--m_updateCount;
 
 		curTicks = GetTickCount()-curTicks;