#include "project.h"

/*
 * This code was contributed by Marc Buffat (buffat@mecaflu.ec-lyon.fr).
 * Thanks Marc!!!
 */


/* implementation de gluProject et gluUnproject */
/* M. Buffat 17/2/95 */


/*
 * Transform a point (column vector) by a 4x4 matrix.  I.e.  out = m * in
 * Input:  m - the 4x4 matrix
 *         in - the 4x1 vector
 * Output:  out - the resulting 4x1 vector.
 */
static void
transform_point(GLfloat out[4], const GLfloat m[16], const GLfloat in[4])
{
#define M(row,col)  m[col*4+row]
   out[0] =
      M(0, 0) * in[0] + M(0, 1) * in[1] + M(0, 2) * in[2] + M(0, 3) * in[3];
   out[1] =
      M(1, 0) * in[0] + M(1, 1) * in[1] + M(1, 2) * in[2] + M(1, 3) * in[3];
   out[2] =
      M(2, 0) * in[0] + M(2, 1) * in[1] + M(2, 2) * in[2] + M(2, 3) * in[3];
   out[3] =
      M(3, 0) * in[0] + M(3, 1) * in[1] + M(3, 2) * in[2] + M(3, 3) * in[3];
#undef M
}


/*
 * Perform a 4x4 matrix multiplication  (product = a x b).
 * Input:  a, b - matrices to multiply
 * Output:  product - product of a and b
 */
static void
matmul(GLfloat * product, const GLfloat * a, const GLfloat * b)
{
   /* This matmul was contributed by Thomas Malik */
   GLfloat temp[16];
   GLint i;

#define A(row,col)  a[(col<<2)+row]
#define B(row,col)  b[(col<<2)+row]
#define T(row,col)  temp[(col<<2)+row]

   /* i-te Zeile */
   for (i = 0; i < 4; i++) {
      T(i, 0) =
	 A(i, 0) * B(0, 0) + A(i, 1) * B(1, 0) + A(i, 2) * B(2, 0) + A(i,
								       3) *
	 B(3, 0);
      T(i, 1) =
	 A(i, 0) * B(0, 1) + A(i, 1) * B(1, 1) + A(i, 2) * B(2, 1) + A(i,
								       3) *
	 B(3, 1);
      T(i, 2) =
	 A(i, 0) * B(0, 2) + A(i, 1) * B(1, 2) + A(i, 2) * B(2, 2) + A(i,
								       3) *
	 B(3, 2);
      T(i, 3) =
	 A(i, 0) * B(0, 3) + A(i, 1) * B(1, 3) + A(i, 2) * B(2, 3) + A(i,
								       3) *
	 B(3, 3);
   }

#undef A
#undef B
#undef T
  memcpy(product, temp, 16 * sizeof(GLfloat));
}


/*
 * Compute inverse of 4x4 transformation matrix.
 * Code contributed by Jacques Leroy jle@star.be
 * Return GL_TRUE for success, GL_FALSE for failure (singular matrix)
 */
static GLboolean
invert_matrix(const GLfloat * m, GLfloat * out)
{
/* NB. OpenGL Matrices are COLUMN major. */
#define SWAP_ROWS(a, b) { GLfloat *_tmp = a; (a)=(b); (b)=_tmp; }
#define MAT(m,r,c) (m)[(c)*4+(r)]

   GLfloat wtmp[4][8];
   GLfloat m0, m1, m2, m3, s;
   GLfloat *r0, *r1, *r2, *r3;

   r0 = wtmp[0], r1 = wtmp[1], r2 = wtmp[2], r3 = wtmp[3];

   r0[0] = MAT(m, 0, 0), r0[1] = MAT(m, 0, 1),
      r0[2] = MAT(m, 0, 2), r0[3] = MAT(m, 0, 3),
      r0[4] = 1.0, r0[5] = r0[6] = r0[7] = 0.0,
      r1[0] = MAT(m, 1, 0), r1[1] = MAT(m, 1, 1),
      r1[2] = MAT(m, 1, 2), r1[3] = MAT(m, 1, 3),
      r1[5] = 1.0, r1[4] = r1[6] = r1[7] = 0.0,
      r2[0] = MAT(m, 2, 0), r2[1] = MAT(m, 2, 1),
      r2[2] = MAT(m, 2, 2), r2[3] = MAT(m, 2, 3),
      r2[6] = 1.0, r2[4] = r2[5] = r2[7] = 0.0,
      r3[0] = MAT(m, 3, 0), r3[1] = MAT(m, 3, 1),
      r3[2] = MAT(m, 3, 2), r3[3] = MAT(m, 3, 3),
      r3[7] = 1.0, r3[4] = r3[5] = r3[6] = 0.0;

   /* choose pivot - or die */
   if (fabs(r3[0]) > fabs(r2[0]))
      SWAP_ROWS(r3, r2);
   if (fabs(r2[0]) > fabs(r1[0]))
      SWAP_ROWS(r2, r1);
   if (fabs(r1[0]) > fabs(r0[0]))
      SWAP_ROWS(r1, r0);
   if (0.0 == r0[0])
      return GL_FALSE;

   /* eliminate first variable     */
   m1 = r1[0] / r0[0];
   m2 = r2[0] / r0[0];
   m3 = r3[0] / r0[0];
   s = r0[1];
   r1[1] -= m1 * s;
   r2[1] -= m2 * s;
   r3[1] -= m3 * s;
   s = r0[2];
   r1[2] -= m1 * s;
   r2[2] -= m2 * s;
   r3[2] -= m3 * s;
   s = r0[3];
   r1[3] -= m1 * s;
   r2[3] -= m2 * s;
   r3[3] -= m3 * s;
   s = r0[4];
   if (s != 0.0) {
      r1[4] -= m1 * s;
      r2[4] -= m2 * s;
      r3[4] -= m3 * s;
   }
   s = r0[5];
   if (s != 0.0) {
      r1[5] -= m1 * s;
      r2[5] -= m2 * s;
      r3[5] -= m3 * s;
   }
   s = r0[6];
   if (s != 0.0) {
      r1[6] -= m1 * s;
      r2[6] -= m2 * s;
      r3[6] -= m3 * s;
   }
   s = r0[7];
   if (s != 0.0) {
      r1[7] -= m1 * s;
      r2[7] -= m2 * s;
      r3[7] -= m3 * s;
   }

   /* choose pivot - or die */
   if (fabs(r3[1]) > fabs(r2[1]))
      SWAP_ROWS(r3, r2);
   if (fabs(r2[1]) > fabs(r1[1]))
      SWAP_ROWS(r2, r1);
   if (0.0 == r1[1])
      return GL_FALSE;

   /* eliminate second variable */
   m2 = r2[1] / r1[1];
   m3 = r3[1] / r1[1];
   r2[2] -= m2 * r1[2];
   r3[2] -= m3 * r1[2];
   r2[3] -= m2 * r1[3];
   r3[3] -= m3 * r1[3];
   s = r1[4];
   if (0.0 != s) {
      r2[4] -= m2 * s;
      r3[4] -= m3 * s;
   }
   s = r1[5];
   if (0.0 != s) {
      r2[5] -= m2 * s;
      r3[5] -= m3 * s;
   }
   s = r1[6];
   if (0.0 != s) {
      r2[6] -= m2 * s;
      r3[6] -= m3 * s;
   }
   s = r1[7];
   if (0.0 != s) {
      r2[7] -= m2 * s;
      r3[7] -= m3 * s;
   }

   /* choose pivot - or die */
   if (fabs(r3[2]) > fabs(r2[2]))
      SWAP_ROWS(r3, r2);
   if (0.0 == r2[2])
      return GL_FALSE;

   /* eliminate third variable */
   m3 = r3[2] / r2[2];
   r3[3] -= m3 * r2[3], r3[4] -= m3 * r2[4],
      r3[5] -= m3 * r2[5], r3[6] -= m3 * r2[6], r3[7] -= m3 * r2[7];

   /* last check */
   if (0.0 == r3[3])
      return GL_FALSE;

   s = 1.0 / r3[3];		/* now back substitute row 3 */
   r3[4] *= s;
   r3[5] *= s;
   r3[6] *= s;
   r3[7] *= s;

   m2 = r2[3];			/* now back substitute row 2 */
   s = 1.0 / r2[2];
   r2[4] = s * (r2[4] - r3[4] * m2), r2[5] = s * (r2[5] - r3[5] * m2),
      r2[6] = s * (r2[6] - r3[6] * m2), r2[7] = s * (r2[7] - r3[7] * m2);
   m1 = r1[3];
   r1[4] -= r3[4] * m1, r1[5] -= r3[5] * m1,
      r1[6] -= r3[6] * m1, r1[7] -= r3[7] * m1;
   m0 = r0[3];
   r0[4] -= r3[4] * m0, r0[5] -= r3[5] * m0,
      r0[6] -= r3[6] * m0, r0[7] -= r3[7] * m0;

   m1 = r1[2];			/* now back substitute row 1 */
   s = 1.0 / r1[1];
   r1[4] = s * (r1[4] - r2[4] * m1), r1[5] = s * (r1[5] - r2[5] * m1),
      r1[6] = s * (r1[6] - r2[6] * m1), r1[7] = s * (r1[7] - r2[7] * m1);
   m0 = r0[2];
   r0[4] -= r2[4] * m0, r0[5] -= r2[5] * m0,
      r0[6] -= r2[6] * m0, r0[7] -= r2[7] * m0;

   m0 = r0[1];			/* now back substitute row 0 */
   s = 1.0 / r0[0];
   r0[4] = s * (r0[4] - r1[4] * m0), r0[5] = s * (r0[5] - r1[5] * m0),
      r0[6] = s * (r0[6] - r1[6] * m0), r0[7] = s * (r0[7] - r1[7] * m0);

   MAT(out, 0, 0) = r0[4];
   MAT(out, 0, 1) = r0[5], MAT(out, 0, 2) = r0[6];
   MAT(out, 0, 3) = r0[7], MAT(out, 1, 0) = r1[4];
   MAT(out, 1, 1) = r1[5], MAT(out, 1, 2) = r1[6];
   MAT(out, 1, 3) = r1[7], MAT(out, 2, 0) = r2[4];
   MAT(out, 2, 1) = r2[5], MAT(out, 2, 2) = r2[6];
   MAT(out, 2, 3) = r2[7], MAT(out, 3, 0) = r3[4];
   MAT(out, 3, 1) = r3[5], MAT(out, 3, 2) = r3[6];
   MAT(out, 3, 3) = r3[7];

   return GL_TRUE;

#undef MAT
#undef SWAP_ROWS
}


// projection du point (objx,objy,obz) sur l'ecran (winx,winy,winz)
GLint //GLAPIENTRY
gluProject(GLfloat objx, GLfloat objy, GLfloat objz,
	   const GLfloat model[16], const GLfloat proj[16],
	   const GLint viewport[4],
	   GLfloat * winx, GLfloat * winy, GLfloat * winz)
{
   // matrice de transformation
   GLfloat in[4], out[4];

   // initilise la matrice et le vecteur a transformer
   in[0] = objx;
   in[1] = objy;
   in[2] = objz;
   in[3] = 1.0;
   transform_point(out, model, in);
   transform_point(in, proj, out);

   // d'ou le resultat normalise entre -1 et 1
   if (in[3] == 0.0)
      return GL_FALSE;

   in[0] /= in[3];
   in[1] /= in[3];
   in[2] /= in[3];

   // en coordonnees ecran
   *winx = viewport[0] + (1 + in[0]) * viewport[2] / 2;
   *winy = viewport[1] + (1 + in[1]) * viewport[3] / 2;
   // entre 0 et 1 suivant z
   *winz = (1 + in[2]) / 2;
   return GL_TRUE;
}


/* transformation du point ecran (winx,winy,winz) en point objet */
GLint //GLAPIENTRY
gluUnProject(GLfloat winx, GLfloat winy, GLfloat winz,
	     const GLfloat model[16], const GLfloat proj[16],
	     const GLint viewport[4],
	     GLfloat * objx, GLfloat * objy, GLfloat * objz)
{
   /* matrice de transformation */
   GLfloat m[16], A[16];
   GLfloat in_[4], out_[4];

   /* transformation coordonnees normalisees entre -1 et 1 */
   in_[0] = (winx - viewport[0]) * 2 / viewport[2] - 1.0;
   in_[1] = (winy - viewport[1]) * 2 / viewport[3] - 1.0;
   in_[2] = 2 * winz - 1.0;
   in_[3] = 1.0;
  
   /* calcul transformation inverse */
   matmul(A, proj, model);
   invert_matrix(A, m);

   /* d'ou les coordonnees objets */
   transform_point(out_, m, in_);
   if (out_[3] == 0.0)
      return GL_FALSE;
   *objx = out_[0] / out_[3];
   *objy = out_[1] / out_[3];
   *objz = out_[2] / out_[3];
   return GL_TRUE;
}


/*
 * New in GLU 1.3
 * This is like gluUnProject but also takes near and far DepthRange values.
 */
 /*
#ifdef GLU_VERSION_1_3
GLint GLAPIENTRY
gluUnProject4(GLfloat winx, GLfloat winy, GLfloat winz, GLfloat clipw,
	      const GLfloat modelMatrix[16],
	      const GLfloat projMatrix[16],
	      const GLint viewport[4],
	      GLclampd nearZ, GLclampd farZ,
	      GLfloat * objx, GLfloat * objy, GLfloat * objz,
	      GLfloat * objw)
{
   // matrice de transformation
   GLfloat m[16], A[16];
   GLfloat in[4], out[4];
   GLfloat z = nearZ + winz * (farZ - nearZ);

   // transformation coordonnees normalisees entre -1 et 1
   in[0] = (winx - viewport[0]) * 2 / viewport[2] - 1.0;
   in[1] = (winy - viewport[1]) * 2 / viewport[3] - 1.0;
   in[2] = 2.0 * z - 1.0;
   in[3] = clipw;

   // calcul transformation inverse
   matmul(A, projMatrix, modelMatrix);
   invert_matrix(A, m);

   // d'ou les coordonnees objets
   transform_point(out, m, in);
   if (out[3] == 0.0)
      return GL_FALSE;
   *objx = out[0] / out[3];
   *objy = out[1] / out[3];
   *objz = out[2] / out[3];
   *objw = out[3];
   return GL_TRUE;
}
*/
