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