o3de/Code/Editor/Util/DynamicArray2D.cpp

/*
 * Copyright (c) Contributors to the Open 3D Engine Project.
 * For complete copyright and license terms please see the LICENSE at the root of this distribution.
 *
 * SPDX-License-Identifier: Apache-2.0 OR MIT
 *
 */


#include "EditorDefs.h"

#include "DynamicArray2D.h"

// Editor
#include "Util/fastlib.h"

//////////////////////////////////////////////////////////////////////
// Construction / destruction
//////////////////////////////////////////////////////////////////////

CDynamicArray2D::CDynamicArray2D(unsigned int iDimension1, unsigned int iDimension2)
{
    ////////////////////////////////////////////////////////////////////////
    // Declare a 2D array on the free store
    ////////////////////////////////////////////////////////////////////////

    unsigned int i;

    // Save the position of the array dimensions
    m_Dimension1 = iDimension1;
    m_Dimension2 = iDimension2;

    // First dimension
    m_Array = new float* [m_Dimension1];
    assert(m_Array);

    // Second dimension
    for (i = 0; i < m_Dimension1; ++i)
    {
        m_Array[i] = new float[m_Dimension2];

        // Init all fields with 0
        memset(&m_Array[i][0], 0, m_Dimension2 * sizeof(float));
    }
}

CDynamicArray2D::~CDynamicArray2D()
{
    ////////////////////////////////////////////////////////////////////////
    // Remove the 2D array and all its sub arrays from the free store
    ////////////////////////////////////////////////////////////////////////

    unsigned int i;

    for (i = 0; i < m_Dimension1; ++i)
    {
        delete [] m_Array[i];
    }

    delete [] m_Array;
    m_Array = nullptr;
}


void CDynamicArray2D::ScaleImage(CDynamicArray2D* pDestination)
{
    ////////////////////////////////////////////////////////////////////////
    // Scale an image stored (in an array class) to a new size
    ////////////////////////////////////////////////////////////////////////

    unsigned int i, j, iOldWidth;
    int iXSrcFl, iXSrcCe, iYSrcFl, iYSrcCe;
    float fXSrc, fYSrc;
    float fHeight[4];
    float fHeightWeight[4];
    float fHeightBottom;
    float fHeightTop;

    assert(pDestination);
    assert(pDestination->m_Dimension1 > 1);

    // Width has to be zero based, not a count
    iOldWidth = m_Dimension1 - 1;

    // Loop trough each field of the new image and interpolate the value
    // from the source heightmap
    for (i = 0; i < pDestination->m_Dimension1; i++)
    {
        // Calculate the average source array position
        fXSrc = i / (float) pDestination->m_Dimension1 * iOldWidth;
        assert(fXSrc >= 0.0f && fXSrc <= iOldWidth);

        // Precalculate floor and ceiling values. Use fast asm integer floor and
        // fast asm float / integer conversion
        iXSrcFl = ifloor(fXSrc);
        iXSrcCe = FloatToIntRet((float) ceil(fXSrc));

        // Distribution between left and right height values
        fHeightWeight[0] = (float) iXSrcCe - fXSrc;
        fHeightWeight[1] = fXSrc - (float) iXSrcFl;

        // Avoid error when floor() and ceil() return the same value
        if (fHeightWeight[0] == 0.0f && fHeightWeight[1] == 0.0f)
        {
            fHeightWeight[0] = 0.5f;
            fHeightWeight[1] = 0.5f;
        }

        for (j = 0; j < pDestination->m_Dimension1; j++)
        {
            // Calculate the average source array position
            fYSrc = j / (float) pDestination->m_Dimension1 * iOldWidth;
            assert(fYSrc >= 0.0f && fYSrc <= iOldWidth);

            // Precalculate floor and ceiling values. Use fast asm integer floor and
            // fast asm float / integer conversion
            iYSrcFl = ifloor(fYSrc);
            iYSrcCe = FloatToIntRet((float) ceil(fYSrc));

            // Get the four nearest height values
            fHeight[0] = m_Array[iXSrcFl][iYSrcFl];
            fHeight[1] = m_Array[iXSrcCe][iYSrcFl];
            fHeight[2] = m_Array[iXSrcFl][iYSrcCe];
            fHeight[3] = m_Array[iXSrcCe][iYSrcCe];

            // Calculate how much weight each height value has

            // Distribution between top and bottom height values
            fHeightWeight[2] = (float) iYSrcCe - fYSrc;
            fHeightWeight[3] = fYSrc - (float) iYSrcFl;

            // Avoid error when floor() and ceil() return the same value
            if (fHeightWeight[2] == 0.0f && fHeightWeight[3] == 0.0f)
            {
                fHeightWeight[2] = 0.5f;
                fHeightWeight[3] = 0.5f;
            }

            // Interpolate between the four nearest height values

            // Get the height for the given X position trough interpolation between
            // the left and the right height
            fHeightBottom = (fHeight[0] * fHeightWeight[0] + fHeight[1] * fHeightWeight[1]);
            fHeightTop    = (fHeight[2] * fHeightWeight[0] + fHeight[3] * fHeightWeight[1]);

            // Set the new value in the destination heightmap
            pDestination->m_Array[i][j] = fHeightBottom * fHeightWeight[2] + fHeightTop * fHeightWeight[3];
        }
    }
}