#include <TH2F.h>
#include <TRotation.h>
#include <TVector3.h>
#include <TImage.h>
#include <TMath.h>

void Rotate(float angle){

  TH2F * h2 = (TH2F*)gROOT->FindObject("h2");
  if(h2)delete h2;
  h2 = new TH2F("h2", "h2", 400, 0.0, 399.0, 399, 0.0, 399.0); 

  TH2F * ht = (TH2F*)gROOT->FindObject("ht");
  if(ht)delete ht;
  ht = new TH2F("ht", "ht", 400, 0.0, 399.0, 399, 0.0, 399.0); 

  TH2F * ha = (TH2F*)gROOT->FindObject("ha");
  if(ha)delete ha;
  ha = new TH2F("ha", "ha", 400, 0.0, 399.0, 399, 0.0, 399.0); 

  Int_t nx = h2->GetNbinsX();
  Int_t ny = h2->GetNbinsY();

  //origo is in 400/2, 400/2
  Int_t x0 = 200;
  Int_t y0 = 200;

  for(Int_t i = 0; i < nx; i++){
    h2->Fill(x0, i);
  }
  for(Int_t j = 0; j < ny; j++){
    h2->Fill(j, y0);
  }

  angle = angle * TMath::Pi()/180.0; //so input can be in degrees
  for(Int_t it = 0; it < 90; it++){
    angle = angle+(1.0*TMath::Pi()/180.0);//increase angle by 1 degree
    cout << "it: " << it << endl;//where are we?
    float t = 0.0;
    ht->Reset();
    for(Int_t i = 0; i < nx; i++){
      for(Int_t j = 0; j < ny; j++){
	TVector3 v(i+1 - x0, j+1 - y0, 0);
	t = h2->GetCellContent(i+1, j+1);
	v.RotateZ(angle);
	ht->Fill(v.X() + x0, v.Y() + y0, t);
      }
    }
    Double_t *array1 = new Double_t[nx*ny]; 
    for (Int_t j=0;j<ny;j++) { 
      for (Int_t i=0;i<nx;i++) { 
        array1[nx*j+i] = ht->GetCellContent(i+1,j+1); 
      }
    }
    TImage *img1 = TImage::Create();
    img1->SetImage(array1,nx,ny,gHistImagePalette); 
    img1->WriteImage("animrot.gif+");
    delete img1;
  }
}