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#ifndef lint
static char SccsId[] = "%W% %G%";
#endif
/* Module: crdsynth.c (Coordinate Synthesis)
* Purpose: Support the computing of transform matrices and shortcuts
* Subroutine: invert_transform() returns: void
* Subroutine: compute_iadd() returns: void
* Subroutine: combine_transform() returns: void
* Subroutine: set_trans_speed() returns: void
* Xlib calls: none
* Copyright: 1988 Smithsonian Astrophysical Observatory
* You may do anything you like with this file except remove
* this copyright. The Smithsonian Astrophysical Observatory
* makes no representations about the suitability of this
* software for any purpose. It is provided "as is" without
* express or implied warranty.
* Modified: {0} Michael VanHilst initial version 16 March 1988
* {n} <who> -- <does what> -- <when>
*/
#include <stdio.h> /* stderr, NULL, etc */
#include <math.h> /* get trig functions, sqrt, and fabs */
#include "hfiles/coord.h" /* coord structs */
/*
* Subroutine: invert_transform
* Purpose: Create matrix to perform opposite transformation
* Given AtoB (old) and Bsys ioff, compute BtoA (new)
*/
void invert_transform ( new, old, ioff )
Transform *new, *old; /* pointers for new and original transforms */
float ioff; /* integer coord to real translation factor */
{
void invert_matrix(), compute_iadd_invert(), set_trans_speed();
#ifdef DEBUG
void exit_errmsg();
/* check for undifined coordinate transforms */
if( ((old->inx_outx ==0) && (old->iny_outx ==0)) ||
((old->inx_outy ==0) && (old->iny_outy ==0)) ) {
exit_errmsg("indeterminate coordinate transform!");
}
#endif
/* check for simplified cases of orthogonal transform */
if( (old->iny_outx ==0) && (old->inx_outy ==0) ) {
new->iny_outx = 0.0;
new->inx_outy = 0.0;
new->inx_outx = 1.0 / old->inx_outx;
new->iny_outy = 1.0 / old->iny_outy;
new->add_outx = -old->add_outx * new->inx_outx;
new->add_outy = -old->add_outy * new->iny_outy;
new->iadd_outx = (-old->add_outx + ioff) * new->inx_outx;
new->iadd_outy = (-old->add_outy + ioff) * new->iny_outy;
} else if( (old->inx_outx ==0) && (old->iny_outy ==0) ) {
new->inx_outx = 0.0;
new->iny_outy = 0.0;
new->iny_outx = 1.0 / old->inx_outy;
new->inx_outy = 1.0 / old->iny_outx;
new->add_outx = -old->add_outy * new->iny_outx;
new->add_outy = -old->add_outx * new->inx_outy;
new->iadd_outx = (-old->add_outy + ioff) * new->iny_outx;
new->iadd_outy = (-old->add_outx + ioff) * new->inx_outy;
} else {
/* compute parameters by matrix inversion */
invert_matrix(old, new);
compute_iadd_invert(old, new, ioff);
}
/* set rotation flag */
new->no_rot = old->no_rot;
/* set parameters for speedy integer calculations */
set_trans_speed(new);
}
#ifdef NOTNEEDED /* %% not currently needed */
/*
* Subroutine: compute_iadd
* Purpose: Compute the offsets used for integer transforms
*/
void compute_iadd ( old, new, ioff )
Transform *old, *new;
float ioff;
{
void compute_iadd_invert();
/* check for simplified cases of orthogonal transform */
if( (new->iny_outx ==0) && (new->inx_outy ==0) ) {
new->iadd_outx = new->add_outx + (ioff * new->inx_outx);
new->iadd_outy = new->add_outy + (ioff * new->iny_outy);
} else if( (new->inx_outx ==0) && (new->iny_outy ==0) ) {
new->iadd_outx = new->add_outx + (ioff * new->iny_outx);
new->iadd_outy = new->add_outy + (ioff * new->inx_outy);
} else {
/* if no simple solution, carry offset through from inverse transform */
compute_iadd_invert(old, new, ioff);
}
}
#endif
/*
* Subroutine: combine_transform
* combine two sets of transform parameters into a single set
* first and second apply to sequence starting with the input values
* algorithm is 3x3 matrix multiplication (3rd row is 0 0 1)
* combination[i][j] is sum of products of column j of 1st and row i of 2nd
*/
void combine_transform ( new, first, second )
Transform *new, *first, *second;
{
void set_trans_speed();
new->inx_outx = ((second->inx_outx * first->inx_outx) +
(second->iny_outx * first->inx_outy));
new->iny_outx = ((second->inx_outx * first->iny_outx) +
(second->iny_outx * first->iny_outy));
new->add_outx = ((second->inx_outx * first->add_outx) +
(second->iny_outx * first->add_outy) +
second->add_outx);
new->inx_outy = ((second->inx_outy * first->inx_outx) +
(second->iny_outy * first->inx_outy));
new->iny_outy = ((second->inx_outy * first->iny_outx) +
(second->iny_outy * first->iny_outy));
new->add_outy = ((second->inx_outy * first->add_outx) +
(second->iny_outy * first->add_outy) +
second->add_outy);
/* compute offset factor for transform starting with an integer value */
/* use integer input offset of first and float offset of second */
new->iadd_outx = ((second->inx_outx * first->iadd_outx) +
(second->iny_outx * first->iadd_outy) +
second->add_outx);
new->iadd_outy = ((second->inx_outy * first->iadd_outx) +
(second->iny_outy * first->iadd_outy) +
second->add_outy);
/* set rotation flag, most cases don't have cross x-y relationships */
new->no_rot = first->no_rot && second->no_rot;
/* set up parameters needed for speedy calculation of transform */
/* uses integer multiply or divide on orthogonal rotations */
set_trans_speed(new);
return;
}
#define EPSILON 0.0001
#define NEGONE -0.9999
#define CLOSE(a,b) (fabs((double)((a)-((float)(b))))<EPSILON)
/*
* Subroutine: set_trans_speed
* Purpose: Set parameters for fast integer computation
*/
void set_trans_speed ( trans )
Transform *trans;
{
int xzm, yzm;
static int integer_test();
trans->ixzoom = 0;
trans->iyzoom = 0;
/* is it an unflipped transform? */
if( CLOSE(trans->iny_outx, 0) && CLOSE(trans->inx_outy, 0) ) {
/* straight forward x->x, y->y transform */
trans->no_rot = 1;
trans->flip = 0;
xzm = integer_test(trans->inx_outx, &trans->ixzoom);
yzm = integer_test(trans->iny_outy, &trans->iyzoom);
} else {
trans->no_rot = 0;
if( CLOSE(trans->inx_outx, 0) && CLOSE(trans->iny_outy, 0) ) {
trans->flip = 1;
xzm = integer_test(trans->iny_outx, &trans->ixzoom);
yzm = integer_test(trans->inx_outy, &trans->iyzoom);
} else {
trans->int_math = 0;
return;
}
}
/* if both zooms can be handled by integer operations ... */
/* ... when given integer inputs, use faster operations */
if( trans->ixzoom && trans->iyzoom ) {
if( (trans->ixzoom == 1) && (trans->iyzoom == 1) ) {
/* if both are zoom 1 */
trans->int_math = 1;
trans->zoom = 0;
} else if( (xzm >= 0) && (yzm >= 0) ) {
/* if both zooms can be integer multiplies, use integer multiply */
trans->int_math = 1;
trans->multiply = 1;
trans->zoom = 1;
} else if( (xzm <= 0) && (yzm <= 0) ) {
/* if both zooms can be integer divides, use float divide */
trans->int_math = 1;
trans->multiply = 0;
trans->zoom = 1;
} else {
/* if its not so simple (mixed operations) don't bother using shortcut */
trans->int_math = 0;
}
} else {
trans->int_math = 0;
}
}
/*
* Subroutine: integer_test
* Returns: 0 if not possible, 1 for zoom up, -1 for zoom down
* Purpose: Test zoom to determine whether it could be computed
* with integer math
*/
static int integer_test ( fzoom, izoom )
double fzoom; /* i: zoom factor (>1, ==1, or <1) */
int *izoom; /* o: integer zoom factor (>1 or ==1) */
{
int ival;
/* test for unity scaling */
if( CLOSE(fzoom, 1) ) {
*izoom = 1;
return( 0 );
}
/* test for even integer multiplies */
if( fzoom > 1.0 ) {
/* round and test for close match */
ival = fzoom + 0.5;
if( CLOSE(fzoom, ival) ) {
*izoom = ival;
return( 1 );
}
} else if( fzoom < NEGONE ) {
ival = fzoom - 0.5;
if( CLOSE(fzoom, ival) ) {
*izoom = ival;
return( 1 );
}
} else if( fzoom != 0.0 ) {
/* test for even integer divides */
fzoom = 1.0 / fzoom;
if( fzoom > 0 ) {
/* round and test for close match */
ival = fzoom + 0.5;
if( CLOSE(fzoom, ival) ) {
*izoom = ival;
return( -1 );
}
} else {
ival = fzoom - 0.5;
if( CLOSE(fzoom, ival) ) {
*izoom = ival;
return( -1 );
}
}
}
#ifdef DEBUG
else
(void)fprintf(stderr, "Warning: Zero zoom factor (CoordSynth.c)\n");
#endif
*izoom = 0;
return( 0 );
}
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