particleCommonFuncs.h

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/**
 * PANDA 3D SOFTWARE
 * Copyright (c) Carnegie Mellon University.  All rights reserved.
 *
 * All use of this software is subject to the terms of the revised BSD
 * license.  You should have received a copy of this license along
 * with this source code in a file named "LICENSE."
 *
 * @file particleCommonFuncs.h
 * @author darren
 * @date 2000-10-02
 */

#ifndef PARTICLECOMMONFUNCS_H
#define PARTICLECOMMONFUNCS_H

// evaluates to a float in the range [0,1]
#define NORMALIZED_RAND() ((PN_stdfloat)rand() / (PN_stdfloat)RAND_MAX)

// linear interpolation t is in [0,1] result is in [X0,X1]
#define LERP(t,X0,X1) ((X0) + ((t) * ((X1) - (X0))))

// linear t -> cubic t t is in [0,1] result is in [0,1]
#define CUBIC_T(t) ((t)*(t)*(3-(2*(t))))

// cubic interpolation t is in [0,1] result is in [X0,X1]
#define CLERP(t,X0,X1) LERP(CUBIC_T(t), (X0), (X1))

// spread calculator spread is non-negative spread magnitude result is in
// [-spread,spread]
#define SPREAD(magnitude) ((magnitude) - (NORMALIZED_RAND() * 2.0f * (magnitude)))

// integer spread calculator spread is non-negative spread magnitude (integer)
// result is in [-spread,spread]
#define I_SPREAD(magnitude) ((magnitude) - ((int)rand() % ((2*(magnitude))+1)))

#endif // PARTICLECOMMONFUNCS_H