noise.cpp
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上传日期:2021-03-01
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- /**
- * @file noise.cpp
- * @brief Perlin noise routines for procedural textures, etc
- *
- * $LicenseInfo:firstyear=2000&license=viewergpl$
- *
- * Copyright (c) 2000-2010, 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);
- }