83 lines
1.7 KiB
C++
83 lines
1.7 KiB
C++
/**
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* @file llviewerlayer.cpp
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* @brief LLViewerLayer class implementation
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*
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* Copyright (c) 2002-$CurrentYear$, Linden Research, Inc.
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* $License$
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*/
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#include "llviewerprecompiledheaders.h"
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#include "llviewerlayer.h"
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#include "llerror.h"
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#include "llmath.h"
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LLViewerLayer::LLViewerLayer(const S32 width, const F32 scale)
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{
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mWidth = width;
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mScale = scale;
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mScaleInv = 1.f/scale;
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mDatap = new F32[width*width];
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for (S32 i = 0; i < width*width; i++)
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{
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*(mDatap + i) = 0.f;
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}
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}
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LLViewerLayer::~LLViewerLayer()
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{
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delete[] mDatap;
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mDatap = NULL;
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}
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F32 LLViewerLayer::getValue(const S32 x, const S32 y) const
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{
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// llassert(x >= 0);
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// llassert(x < mWidth);
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// llassert(y >= 0);
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// llassert(y < mWidth);
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return *(mDatap + x + y*mWidth);
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}
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F32 LLViewerLayer::getValueScaled(const F32 x, const F32 y) const
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{
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S32 x1, x2, y1, y2;
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F32 x_frac, y_frac;
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x_frac = x*mScaleInv;
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x1 = llfloor(x_frac);
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x2 = x1 + 1;
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x_frac -= x1;
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y_frac = y*mScaleInv;
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y1 = llfloor(y_frac);
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y2 = y1 + 1;
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y_frac -= y1;
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x1 = llmin((S32)mWidth-1, x1);
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x1 = llmax(0, x1);
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x2 = llmin((S32)mWidth-1, x2);
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x2 = llmax(0, x2);
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y1 = llmin((S32)mWidth-1, y1);
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y1 = llmax(0, y1);
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y2 = llmin((S32)mWidth-1, y2);
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y2 = llmax(0, y2);
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// Take weighted average of all four points (bilinear interpolation)
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S32 row1 = y1 * mWidth;
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S32 row2 = y2 * mWidth;
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// Access in squential order in memory, and don't use immediately.
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F32 row1_left = mDatap[ row1 + x1 ];
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F32 row1_right = mDatap[ row1 + x2 ];
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F32 row2_left = mDatap[ row2 + x1 ];
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F32 row2_right = mDatap[ row2 + x2 ];
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F32 row1_interp = row1_left - x_frac * (row1_left - row1_right);
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F32 row2_interp = row2_left - x_frac * (row2_left - row2_right);
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return row1_interp - y_frac * (row1_interp - row2_interp);
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}
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