bugfix(view): Fix and improve camera pivoting (TheSuperHackers#2506)

Author: xezon

Core/GameEngine/Include/GameClient/View.h

@@ -131,7 +131,8 @@ class View : public Snapshot
 	virtual void forceRedraw() = 0;
 
 	virtual void lookAt( const Coord3D *o );														///< Center the view on the given coordinate
-	virtual void initHeightForMap() {};														///<  Init the camera height for the map at the current position.
+	virtual void initHeightForMap() {};														///< Init the camera height for the map at the current position.
+	virtual void resetPivotToGround() {};													///< Set the camera pivot to the terrain height at the current position.
 	virtual void scrollBy( const Coord2D *delta );														///< Shift the view by the given delta
 
 	virtual void moveCameraTo(const Coord3D *o, Int frames, Int shutter, Bool orient, Real easeIn=0.0f, Real easeOut=0.0f) { lookAt( o ); }
@@ -204,6 +205,7 @@ class View : public Snapshot
 	Bool userSetZoomToDefault()                          { return doUserAction(&View::setZoomToDefault); }
 	Bool userSetFieldOfView(Real angle)                  { return doUserAction(&View::setFieldOfView, angle); }
 	Bool userLookAt(const Coord3D *o)                    { return doUserAction(&View::lookAt, o); }
+	Bool userResetPivotToGround()                        { return doUserAction(&View::resetPivotToGround); }
 	Bool userScrollBy(const Coord2D *delta)              { return doUserAction(&View::scrollBy, delta); }
 	Bool userSetLocation(const ViewLocation *location)   { return doUserAction(&View::setLocation, location); }
 	Bool userSetCameraLock(ObjectID id)                  { return doUserAction(&View::setCameraLock, id); }

Core/GameEngineDevice/Include/W3DDevice/GameClient/W3DView.h

@@ -175,7 +175,8 @@ class W3DView : public View, public SubsystemInterface
 	virtual void setPitchToDefault() override;									///< Set the view pitch back to default
 
 	virtual void lookAt( const Coord3D *o ) override;											///< Center the view on the given coordinate
-	virtual void initHeightForMap() override;												///<  Init the camera height for the map at the current position.
+	virtual void initHeightForMap() override;												///< Init the camera height for the map at the current position.
+	virtual void resetPivotToGround() override;												///< Set the camera pivot to the terrain height at the current position.
 	virtual void moveCameraTo(const Coord3D *o, Int milliseconds,  Int shutter, Bool orient, Real easeIn, Real easeOut) override;
 	virtual void moveCameraAlongWaypointPath(Waypoint *pWay, Int frames, Int shutter, Bool orient, Real easeIn, Real easeOut) override;
 	virtual Bool isCameraMovementFinished() override;
@@ -290,6 +291,7 @@ class W3DView : public View, public SubsystemInterface
 	void buildCameraPosition(Vector3 &sourcePos, Vector3 &targetPos);
 	void buildCameraTransform(Matrix3D *transform, const Vector3 &sourcePos, const Vector3 &targetPos); ///< calculate (but do not set) the transform matrix of m_3DCamera, based on m_pos & m_angle
 	Bool zoomCameraToDesiredHeight();
+	Bool movePivotToGround();
 	void updateCameraAreaConstraints();
 	void calcCameraAreaConstraints(); ///< Recalculates the camera area constraints
 	Real calcCameraAreaOffset(Real maxEdgeZ, Bool isLookingDown);

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

@@ -435,6 +435,57 @@ Bool W3DView::zoomCameraToDesiredHeight()
 	return false;
 }
 
+//-------------------------------------------------------------------------------------------------
+// TheSuperHackers @bugfix New logic responsible for moving the camera pivot to the terrain ground.
+// This is essential to correctly center the camera above the ground when playing.
+Bool W3DView::movePivotToGround()
+{
+	const Real fpsRatio = TheFramePacer->getBaseOverUpdateFpsRatio();
+	const Real adjustFactor = TheGlobalData->m_cameraAdjustSpeed * fpsRatio;
+	const Real groundLevel = m_groundLevel;
+	const Real groundLevelDiff = m_terrainHeightAtPivot - groundLevel;
+	if (fabs(groundLevelDiff) > 0.1f)
+	{
+		// Adjust the ground level. This will change the world height of the camera.
+		m_groundLevel += groundLevelDiff * adjustFactor;
+
+		// Reposition the camera relative to its pitch.
+		// This effectively zooms the camera in the view direction together with the ground level change.
+		Vector3 sourcePos;
+		Vector3 targetPos;
+		buildCameraPosition(sourcePos, targetPos);
+		const Vector3 delta = targetPos - sourcePos;
+
+		if (fabs(delta.Z) > 0.1f)
+		{
+			Vector2 groundLevelCenter;
+			Vector2 terrainHeightCenter;
+			groundLevelCenter.X = Vector3::Find_X_At_Z(groundLevel, sourcePos, targetPos);
+			groundLevelCenter.Y = Vector3::Find_Y_At_Z(groundLevel, sourcePos, targetPos);
+			terrainHeightCenter.X = Vector3::Find_X_At_Z(m_terrainHeightAtPivot, sourcePos, targetPos);
+			terrainHeightCenter.Y = Vector3::Find_Y_At_Z(m_terrainHeightAtPivot, sourcePos, targetPos);
+			Vector2 posDiff = terrainHeightCenter - groundLevelCenter;
+
+			// Adjust the strength of the repositioning for low camera pitch, because
+			// it feels bad to move the camera around when it looks over the terrain.
+			const Real pitch = WWMath::Asin(fabs(delta.Z) / delta.Length());
+			constexpr const Real lowerPitch = DEG_TO_RADF(15.f);
+			constexpr const Real upperPitch = DEG_TO_RADF(30.f);
+			Real repositionStrength = WWMath::Inverse_Lerp(lowerPitch, upperPitch, pitch);
+			repositionStrength = WWMath::Clamp(repositionStrength, 0.0f, 1.0f);
+			posDiff *= repositionStrength;
+
+			Coord3D pos = *getPosition();
+			pos.x += posDiff.X * adjustFactor;
+			pos.y += posDiff.Y * adjustFactor;
+			setPosition(&pos);
+		}
+
+		return true;
+	}
+	return false;
+}
+
 void W3DView::updateCameraAreaConstraints()
 {
 #if defined(RTS_DEBUG)
@@ -1396,7 +1447,26 @@ void W3DView::update()
 
 		if (adjustZoomWhenScrolling || adjustZoomWhenNotScrolling)
 		{
+			// TheSuperHackers @info The camera zoom has two modes:
+			// 1. Zoom by scaling the distance of the camera origin to the look-at target.
+			//    Used by user zooming and the scripted camera.
+			// 2. Zoom by moving the camera pivot to the ground while repositioning the
+			//    camera origin towards the look-at target. Visually this looks identical
+			//    to (1), but changes the pivot point which is important for the rotation
+			//    origin and map border collisions.
+			Bool isZoomingOrMovingPivot = false;
+
 			if (zoomCameraToDesiredHeight())
+			{
+				isZoomingOrMovingPivot = true;
+			}
+
+			if (movePivotToGround())
+			{
+				isZoomingOrMovingPivot = true;
+			}
+
+			if (isZoomingOrMovingPivot)
 			{
 				m_recalcCamera = true;
 
@@ -2376,16 +2446,18 @@ void W3DView::lookAt( const Coord3D *o )
 //-------------------------------------------------------------------------------------------------
 void W3DView::initHeightForMap()
 {
-	m_groundLevel = TheTerrainLogic->getGroundHeight(m_pos.x, m_pos.y);
-	const Real MAX_GROUND_LEVEL = 120.0; // jba - starting ground level can't exceed this height.
-	if (m_groundLevel>MAX_GROUND_LEVEL) {
-		m_groundLevel = MAX_GROUND_LEVEL;
-	}
+	resetPivotToGround();
 
 	m_cameraOffset.z = m_groundLevel+TheGlobalData->m_cameraHeight;
 	m_cameraOffset.y = -(m_cameraOffset.z / tan(TheGlobalData->m_cameraPitch * (PI / 180.0)));
 	m_cameraOffset.x = -(m_cameraOffset.y * tan(TheGlobalData->m_cameraYaw * (PI / 180.0)));
-	m_cameraAreaConstraintsValid = false;	// possible ground level change invalidates camera constraints
+}
+//-------------------------------------------------------------------------------------------------
+//-------------------------------------------------------------------------------------------------
+void W3DView::resetPivotToGround( void )
+{
+	m_groundLevel = getHeightAroundPos(m_pos.x, m_pos.y);
+	m_cameraAreaConstraintsValid = false; // possible ground level change invalidates camera constraints
 	m_recalcCamera = true;
 }
 

Core/Libraries/Source/WWVegas/WWMath/wwmath.h

@@ -155,8 +155,15 @@ static WWINLINE float		Max(float a, float b);
 
 static WWINLINE int			Float_As_Int(const float f) { return *((int*)&f); }
 
-static WWINLINE float		Lerp(float a, float b, float lerp );
-static WWINLINE double		Lerp(double a, double b, float lerp );
+// Linearly interpolates between a and b using parameter t in [0, 1].
+// t = 0 returns a, t = 1 returns b, values in between return a proportionate blend.
+static WWINLINE float		Lerp(float a, float b, float t);
+static WWINLINE double	Lerp(double a, double b, float t);
+
+// Computes the interpolation parameter t such that v = Lerp(a, b, t).
+// Returns where v lies between a and b as a ratio, typically in [0, 1].
+static WWINLINE float		Inverse_Lerp(float a, float b, float v);
+static WWINLINE double	Inverse_Lerp(double a, double b, float v);
 
 static WWINLINE long			Float_To_Long(double f);
 
@@ -258,16 +265,25 @@ WWINLINE float WWMath::Max(float a, float b)
 	return b;
 }
 
-WWINLINE float WWMath::Lerp(float a, float b, float lerp )
+WWINLINE float WWMath::Lerp(float a, float b, float t)
+{
+	return (a + (b - a)*t);
+}
+
+WWINLINE double WWMath::Lerp(double a, double b, float t)
 {
-	return (a + (b - a)*lerp);
+	return (a + (b - a)*t);
 }
 
-WWINLINE double WWMath::Lerp(double a, double b, float lerp )
+WWINLINE float WWMath::Inverse_Lerp(float a, float b, float v)
 {
-	return (a + (b - a)*lerp);
+	return (v - a) / (b - a);
 }
 
+WWINLINE double WWMath::Inverse_Lerp(double a, double b, float v)
+{
+	return (v - a) / (b - a);
+}
 
 WWINLINE bool WWMath::Is_Valid_Float(float x)
 {

Generals/Code/GameEngine/Source/GameClient/InGameUI.cpp

@@ -4348,9 +4348,10 @@ Bool InGameUI::areSelectedObjectsControllable() const
 //------------------------------------------------------------------------------
 void InGameUI::resetCamera()
 {
-	ViewLocation currentView;
-	TheTacticalView->getLocation( &currentView );
-	TheTacticalView->resetCamera( &currentView.getPosition(), 1 );
+	TheTacticalView->userResetPivotToGround();
+	TheTacticalView->userSetAngleToDefault();
+	TheTacticalView->userSetPitchToDefault();
+	TheTacticalView->userSetZoomToDefault();
 }
 
 //------------------------------------------------------------------------------

Generals/Code/GameEngine/Source/GameClient/MessageStream/LookAtXlat.cpp

@@ -315,6 +315,7 @@ GameMessageDisposition LookAtTranslator::translateGameMessage(const GameMessage
 			// if middle button is "clicked", reset to "home" orientation
 			if (!didMove && elapsedMsec < CLICK_DURATION_MSEC)
 			{
+				TheTacticalView->userResetPivotToGround();
 				TheTacticalView->userSetAngleToDefault();
 				TheTacticalView->userSetPitchToDefault();
 				TheTacticalView->userSetZoomToDefault();

GeneralsMD/Code/GameEngine/Source/GameClient/InGameUI.cpp

@@ -4503,9 +4503,10 @@ Bool InGameUI::areSelectedObjectsControllable() const
 //------------------------------------------------------------------------------
 void InGameUI::resetCamera()
 {
-	ViewLocation currentView;
-	TheTacticalView->getLocation( &currentView );
-	TheTacticalView->resetCamera( &currentView.getPosition(), 1, 0.0f, 0.0f );
+	TheTacticalView->userResetPivotToGround();
+	TheTacticalView->userSetAngleToDefault();
+	TheTacticalView->userSetPitchToDefault();
+	TheTacticalView->userSetZoomToDefault();
 }
 
 //------------------------------------------------------------------------------

GeneralsMD/Code/GameEngine/Source/GameClient/MessageStream/LookAtXlat.cpp

@@ -314,6 +314,7 @@ GameMessageDisposition LookAtTranslator::translateGameMessage(const GameMessage
 			// if middle button is "clicked", reset to "home" orientation
 			if (!didMove && elapsedMsec < CLICK_DURATION_MSEC)
 			{
+				TheTacticalView->userResetPivotToGround();
 				TheTacticalView->userSetAngleToDefault();
 				TheTacticalView->userSetPitchToDefault();
 				TheTacticalView->userSetZoomToDefault();