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/**
* @file noise.cpp
* @brief Perlin noise routines for procedural textures, etc
*
* $LicenseInfo:firstyear=2000&license=viewergpl$
*
* Copyright (c) 2000-2008, Linden Research, Inc.
*
* Second Life Viewer Source Code
* The source code in this file ("Source Code") is provided by Linden Lab
* to you under the terms of the GNU General Public License, version 2.0
* ("GPL"), unless you have obtained a separate licensing agreement
* ("Other License"), formally executed by you and Linden Lab. Terms of
* the GPL can be found in doc/GPL-license.txt in this distribution, or
* online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
*
* There are special exceptions to the terms and conditions of the GPL as
* it is applied to this Source Code. View the full text of the exception
* in the file doc/FLOSS-exception.txt in this software distribution, or
* online at http://secondlifegrid.net/programs/open_source/licensing/flossexception
*
* By copying, modifying or distributing this software, you acknowledge
* that you have read and understood your obligations described above,
* and agree to abide by those obligations.
*
* ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
* WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
* COMPLETENESS OR PERFORMANCE.
* $/LicenseInfo$
*/
#include "llviewerprecompiledheaders.h"
#include "noise.h"
#include "llrand.h"
// static
#define B 0x100
S32 p[B + B + 2];
F32 g3[B + B + 2][3];
F32 g2[B + B + 2][2];
F32 g1[B + B + 2];
S32 gNoiseStart = 1;
F32 noise2(F32 *vec)
{
U8 bx0, bx1, by0, by1;
U32 b00, b10, b01, b11;
F32 rx0, rx1, ry0, ry1, *q, sx, sy, a, b, u, v;
S32 i, j;
if (gNoiseStart) {
gNoiseStart = 0;
init();
}
fast_setup(*vec, bx0, bx1, rx0, rx1);
fast_setup(*(vec + 1), by0, by1, ry0, ry1);
i = *(p + bx0);
j = *(p + bx1);
b00 = *(p + i + by0);
b10 = *(p + j + by0);
b01 = *(p + i + by1);
b11 = *(p + j + by1);
sx = s_curve(rx0);
sy = s_curve(ry0);
q = *(g2 + b00);
u = fast_at2(rx0, ry0, q);
q = *(g2 + b10);
v = fast_at2(rx1, ry0, q);
a = lerp_m(sx, u, v);
q = *(g2 + b01);
u = fast_at2(rx0,ry1,q);
q = *(g2 + b11);
v = fast_at2(rx1,ry1,q);
b = lerp_m(sx, u, v);
return lerp_m(sy, a, b);
}
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