/*****************************************************************************/
/* 
 * File name: MImPolar.c 
 *
 * Synopsis:  This program uses the polar-to-rectangular transformation
 *            to unroll a string.
 */
#include <mil.h>
#include <conio.h>
#include <math.h>

/* Target image specifications. */
#define IMAGE_FILE              M_IMAGE_PATH MIL_TEXT("Polar.mim")

/* Points used to compute the parameters of the circle. */
#define POINT1_X   147
#define POINT1_Y   359
#define POINT2_X   246
#define POINT2_Y   404
#define POINT3_X   354
#define POINT3_Y   368

/* Polar stripe features. */
#define DELTA_RADIUS  25
#define START_ANGLE   210
#define END_ANGLE     330

/* Utility function prototype. */
void GenerateCircle ( double X1, double Y1, double X2, 
                      double Y2, double X3, double Y3, 
                      double *CenterX, double *CenterY, 
                      double *Radius);

/* Main function. */
void main(void)
{
   MIL_ID MilApplication,     /* Application identifier.        */
          MilSystem,          /* System identifier.             */
          MilDisplay,         /* Display identifier.            */
          MilImage,           /* Image buffer identifier.       */
          MilPolarImage;      /* Destination buffer identifier. */      
   double SizeRadius,SizeAngle;
   double CenterX, CenterY, Radius;
   long   OffsetX, OffsetY, SizeX, SizeY;

   /* Allocate defaults. */
   MappAllocDefault(M_SETUP, &MilApplication, &MilSystem, 
                             &MilDisplay, M_NULL, M_NULL);

   /* Load the source image and display it. */
   MbufRestore(IMAGE_FILE, MilSystem, &MilImage);
   MdispSelect(MilDisplay, MilImage);

   /* Calculate the parameters of the circle. */
   GenerateCircle(POINT1_X, POINT1_Y, POINT2_X, POINT2_Y,
                  POINT3_X, POINT3_Y, &CenterX, &CenterY, &Radius);
   
   /* Get the size of the destination buffer. */
   MimPolarTransform(MilImage, M_NULL, CenterX, CenterY, 
                     Radius+DELTA_RADIUS, Radius-DELTA_RADIUS, 
                     START_ANGLE, END_ANGLE, M_RECTANGULAR_TO_POLAR, 
                     M_NEAREST_NEIGHBOR+M_OVERSCAN_ENABLE, 
                     &SizeAngle, &SizeRadius);
   
   /* Allocate the destination buffer. */
   OffsetX  = (long)((MbufInquire(MilImage, M_SIZE_X, M_NULL)/2) - (SizeAngle/2));
   OffsetY  = 20;
   SizeX    = (long)SizeAngle;
   SizeY    = (long)SizeRadius;
   MbufChild2d(MilImage, OffsetX, OffsetY, SizeX, SizeY, &MilPolarImage);
   
   /* Print a message. */
   printf("\nPOLAR TRANSFORMATION:\n");
   printf("---------------------\n\n");
   printf("A string will be unrolled using a polar-to-rectangular transformation.\n");
   printf("Press <Enter> to continue.\n\n");
   getch();
   
   /* Unroll the string. */
   MimPolarTransform(MilImage, MilPolarImage, CenterX, CenterY, 
                     Radius+DELTA_RADIUS, Radius-DELTA_RADIUS, 
                     START_ANGLE, END_ANGLE, M_RECTANGULAR_TO_POLAR, 
                     M_NEAREST_NEIGHBOR+M_OVERSCAN_ENABLE, 
                     &SizeAngle, &SizeRadius);
   
   /* Print a message on the Host screen. */
   printf("Press <Enter> to end.\n");
   getch();
   
   /* Free buffers. */
   MbufFree(MilPolarImage);
   MappFreeDefault(MilApplication, MilSystem, MilDisplay, M_NULL, MilImage);
}


/* GenerateCircle() function returns the center and the radius of a circle 
   defined by 3 non-collinear points.
*/
void GenerateCircle ( double X1, double Y1, double X2, double Y2, double X3, double Y3, 
                                 double *CenterX, double *CenterY, double *Radius)
{
   double Slope1 = 0.0;
   double Slope2 = 0.0;
   double MidPoint1X = 0.0;
   double MidPoint1Y = 0.0;
   double MidPoint2X = 0.0;
   double MidPoint2Y = 0.0;
   double Offset1 = 0.0;
   double Offset2 = 0.0;

   /* Compute the middle points of the two segments. */
   MidPoint1X = (X1+X2)/2;
   MidPoint1Y = (Y1+Y2)/2;
   MidPoint2X = (X2+X3)/2;
   MidPoint2Y = (Y2+Y3)/2;

   /* Compute the slope between points 1 and 2, and between 
      points 2 and 3. */
   if (((Y2-Y1) != 0.0) && ((Y3-Y2) != 0.0))
      {
      Slope1 = -(X2-X1)/(Y2-Y1);
      Slope2 = -(X3-X2)/(Y3-Y2);

      Offset1 = MidPoint1Y - Slope1*MidPoint1X;
      Offset2 = MidPoint2Y - Slope2*MidPoint2X;

      *CenterX = (Offset2-Offset1)/(Slope1-Slope2);
      *CenterY = Slope1*(*CenterX) + Offset1;
      }
   else if (((Y2-Y1) == 0.0) && ((Y3-Y2) != 0.0))
      {
      Slope2 = -(X3-X2)/(Y3-Y2);
      Offset2 = MidPoint2Y - Slope2*MidPoint2X;

      *CenterX = MidPoint1X;
      *CenterY = Slope2*(*CenterX) + Offset2;
      }
   else if (((Y2-Y1) != 0.0) && ((Y3-Y2) == 0.0))
      {
      Slope1 = -(X2-X1)/(Y2-Y1);
      Offset1 = MidPoint1Y - Slope1*MidPoint1X;

      *CenterX = MidPoint2X;
      *CenterY = Slope1*(*CenterX) + Offset1;
      }

   /* Compute the radius. */
   *Radius = sqrt(pow(*CenterX-X1,2) + pow(*CenterY-Y1,2));
}