[TEve] Add XZ projection type. (#7269)

* Add XZ projection

* Get XZ Projection to work for geometry and axis drawing.

Co-authored-by: Yang Hang <yanghang@chao-Lenovo-XiaoXin-300>

graf3d/eve/inc/LinkDef1.h

@@ -198,6 +198,7 @@
 #pragma link C++ typedef TEveProjection::vPreScale_i;
 #pragma link C++ class TEveRhoZProjection+;
 #pragma link C++ class TEveRPhiProjection+;
+#pragma link C++ class TEveXZProjection+;
 #pragma link C++ class TEve3DProjection+;
 
 #pragma link C++ class TEveProjectionManager+;

graf3d/eve/inc/TEveProjections.h

@@ -26,7 +26,7 @@ class TEveTrans;
 class TEveProjection
 {
 public:
-   enum EPType_e   { kPT_Unknown, kPT_RPhi, kPT_RhoZ, kPT_3D, kPT_End }; // projection type
+   enum EPType_e   { kPT_Unknown, kPT_RPhi, kPT_XZ, kPT_RhoZ, kPT_3D, kPT_End }; // projection type
    enum EPProc_e   { kPP_Plane, kPP_Distort, kPP_Full };                 // projection procedure
    enum EGeoMode_e { kGM_Unknown, kGM_Polygons, kGM_Segments };          // strategy for geometry projections
 
@@ -202,6 +202,32 @@ public:
 };
 
 
+//==============================================================================
+// TEveXZProjection
+//==============================================================================
+
+class TEveXZProjection : public TEveProjection
+{
+private:
+   TEveVector   fProjectedCenter; // projected center of distortion.
+
+public:
+   TEveXZProjection();
+   virtual ~TEveXZProjection() {}
+
+   virtual Bool_t Is2D() const { return kTRUE;  }
+   virtual Bool_t Is3D() const { return kFALSE; }
+
+   virtual void   ProjectPoint(Float_t& x, Float_t& y, Float_t& z, Float_t d, EPProc_e proc = kPP_Full);
+
+   virtual void     SetCenter(TEveVector& v);
+   virtual Float_t* GetProjectedCenter() { return fProjectedCenter.Arr(); }
+
+   virtual void     SetDirectionalVector(Int_t screenAxis, TEveVector& vec);
+
+   ClassDef(TEveXZProjection, 0); // XZ non-linear projection.
+};
+
 //==============================================================================
 // TEve3DProjection
 //==============================================================================

graf3d/eve/src/TEveProjectionManager.cxx

@@ -109,6 +109,11 @@ void TEveProjectionManager::SetProjection(TEveProjection::EPType_e type)
             fProjections[type] = new TEveRPhiProjection();
             break;
          }
+         case TEveProjection::kPT_XZ:
+         {
+            fProjections[type] = new TEveXZProjection();
+            break;
+         }
          case TEveProjection::kPT_RhoZ:
          {
             fProjections[type] = new TEveRhoZProjection();

graf3d/eve/src/TEveProjectionManagerEditor.cxx

@@ -50,6 +50,7 @@ TEveProjectionManagerEditor::TEveProjectionManagerEditor(const TGWindow *p,
       f->AddFrame(lab, new TGLayoutHints(kLHintsLeft|kLHintsBottom, 1, 31, 1, 2));
       fType = new TGComboBox(f);
       fType->AddEntry("RPhi", TEveProjection::kPT_RPhi);
+      fType->AddEntry("XZ",   TEveProjection::kPT_XZ);
       fType->AddEntry("RhoZ", TEveProjection::kPT_RhoZ);
       fType->AddEntry("3D",   TEveProjection::kPT_3D);
       TGListBox* lb = fType->GetListBox();

graf3d/eve/src/TEveProjections.cxx

@@ -580,7 +580,6 @@ void TEveRhoZProjection::ProjectPoint(Float_t& x, Float_t& y, Float_t& z,
       if (fUsePreScale)
          PreScalePoint(y, x);
 
-
       // distort
 
       if (!fDisplaceOrigin) {
@@ -762,9 +761,121 @@ void TEveRPhiProjection::ProjectPoint(Float_t& x, Float_t& y, Float_t& z,
          y += fCenter.fY;
       }
    }
+
    z = d;
 }
 
+/** \class TEveXZProjection
+\ingroup TEve
+XZ projection with distortion around given center.
+*/
+
+ClassImp(TEveXZProjection);
+
+////////////////////////////////////////////////////////////////////////////////
+/// Constructor.
+
+TEveXZProjection::TEveXZProjection() :
+   TEveProjection()
+{
+   fType    = kPT_XZ;
+   fGeoMode = kGM_Polygons;
+   fName    = "XZ";
+}
+
+////////////////////////////////////////////////////////////////////////////////
+/// Project point.
+
+void TEveXZProjection::ProjectPoint(Float_t& x, Float_t& y, Float_t& z,
+                                    Float_t d, EPProc_e proc)
+{
+   using namespace TMath;
+   
+   if (fDisplaceOrigin)
+   {
+      x  -= fCenter.fX;
+      y  -= fCenter.fY;
+      z  -= fCenter.fZ;
+   }
+
+   // projection
+   if (proc == kPP_Plane || proc == kPP_Full)
+   {
+      y = z;
+      z = d;
+   }
+   if (proc != kPP_Distort || proc == kPP_Full)
+   {
+      Float_t r, phi;
+      if (fUsePreScale)
+      {
+         r   = Sqrt(x*x + y*y);
+         phi = (x == 0.0f && y == 0.0f) ? 0.0f : ATan2(y, x);
+         PreScalePoint(r, phi);
+         x = r*Cos(phi);
+         y = r*Sin(phi);
+      }
+
+      if (!fDisplaceOrigin)
+      {
+         x -= fProjectedCenter.fX;
+         y -= fProjectedCenter.fY;
+      }
+
+      r   = Sqrt(x*x + y*y);
+      phi = (x == 0.0f && y == 0.0f) ? 0.0f : ATan2(y, x);
+
+      if (r > fFixR)
+         r =  fFixR + fPastFixRScale*(r - fFixR);
+      else if (r < -fFixR)
+         r = -fFixR + fPastFixRScale*(r + fFixR);
+      else
+         r =  r * fScaleR / (1.0f + r*fDistortion);
+
+      x = r*Cos(phi);
+      y = r*Sin(phi);
+
+      if (!fDisplaceOrigin)
+      {
+         x += fProjectedCenter.fX;
+         y += fProjectedCenter.fY;
+      }
+   }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+/// Set center of distortion (virtual method).
+
+void TEveXZProjection::SetCenter(TEveVector& v)
+{
+   fCenter = v;
+
+   if (fDisplaceOrigin)
+   {
+      fProjectedCenter.Set(0.f, 0.f, 0.f);
+   }
+   else
+   {
+      fProjectedCenter.fX = fCenter.fX;
+      fProjectedCenter.fY = fCenter.fZ;
+      fProjectedCenter.fZ = 0;
+   }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+/// Get direction in the unprojected space for axis index in the
+/// projected space.
+/// This is virtual method from base-class TEveProjection.
+
+void TEveXZProjection::SetDirectionalVector(Int_t screenAxis, TEveVector& vec)
+{
+   if (screenAxis == 0)
+      vec.Set(1.0f, 0.0f, 0.0f);
+   else if (screenAxis == 1)
+      vec.Set(0.0f, 0.0f, 1.0f);
+}
+
+
 /** \class TEve3DProjection
 \ingroup TEve
 3D scaling projection. One has to use pre-scaling to make any ise of this.