/*
 * scale.c
 *
 * Copyright (C) 1989, 1991, Craig E. Kolb
 * All rights reserved.
 *
 * This software may be freely copied, modified, and redistributed
 * provided that this copyright notice is preserved on all copies.
 *
 * You may not distribute this software, in whole or in part, as part of
 * any commercial product without the express consent of the authors.
 * 
 * There is no warranty or other guarantee of fitness of this software
 * for any purpose.  It is provided solely "as is".
 *
 * $Id: scale.c,v 4.0 91/07/17 14:32:08 kolb Exp Locker: kolb $
 *
 * $Log:	scale.c,v $
 * Revision 4.0  91/07/17  14:32:08  kolb
 * Initial version.
 * 
 */
#include "common.h"
#include "scale.h"

TransMethods *iScaleMethods;
void ScaleMatrix();

Scale *
ScaleCreate()
{
	Scale *res;

	res = (Scale *)Malloc(sizeof(Scale));
	res->x = res->y = res->z = 1.;
	return res;
}

TransMethods *
ScaleMethods()
{
	if (iScaleMethods == (TransMethods *)NULL) {
		iScaleMethods = (TransMethods *)Malloc(sizeof(TransMethods));
		iScaleMethods->create = (TransCreateFunc *)ScaleCreate;
		iScaleMethods->propagate = ScalePropagate;
	}
	return iScaleMethods;	
}

void
ScalePropagate(scale, trans, itrans)
Scale *scale;
RSMatrix *trans, *itrans;
{
	if (equal(scale->x, 0.) || equal(scale->y, 0.) || equal(scale->z, 0.))
		RLerror(RL_PANIC, "Degenerate scale %g %g %g\n", scale->x, scale->y, scale->z);
	ScaleMatrix(scale->x, scale->y, scale->z, trans);
	/*
	 * Build the inverse
	 */
	MatrixInit(itrans);
	itrans->matrix[0][0] = 1. / scale->x;
	itrans->matrix[1][1] = 1. / scale->y;
	itrans->matrix[2][2] = 1. / scale->z;
}

void
ScaleMatrix(x, y, z, mat)
Float x, y, z;
RSMatrix *mat;
{
	MatrixInit(mat);
	mat->matrix[0][0] = x;
	mat->matrix[1][1] = y;
	mat->matrix[2][2] = z;
}