//==============================================================
//==============================================================
//= terrain.cpp ================================================
//= Original coders: Trent Polack (trent@voxelsoft.com)          =
//==============================================================
//= This file contains the information for the "parent" terrain=
//= class, which all specific implementations are derived from,=
//= also contains other general data structures and constants. =
//==============================================================
//==============================================================//--------------------------------------------------------------
//--------------------------------------------------------------
//- HEADERS AND LIBRARIES --------------------------------------
//--------------------------------------------------------------
//--------------------------------------------------------------
#include <stdio.h>
#include <math.h>#include "../Base Code/gl_app.h"#include "terrain.h"//--------------------------------------------------------------
//--------------------------------------------------------------
//- DEFINITIONS ------------------------------------------------
//--------------------------------------------------------------
//--------------------------------------------------------------//--------------------------------------------------------------
// Name:            CTERRAIN::LoadHeightMap - public
// Description:     Load a grayscale RAW height map
// Arguments:       -szFilename: the file name of the height map
//                  -im_iSize: the m_iSize (power of 2) of the map
// Return Value:    A boolean value: -true: successful load
//                                   -false: unsuccessful load
//--------------------------------------------------------------
bool CTERRAIN::LoadHeightMap( char* szFilename, int iSize )
{FILE* pFile;//check to see if the data has been setif( m_heightData.m_ucpData )UnloadHeightMap( );//open the RAW height map datasetpFile= fopen( szFilename, "rb" );if( pFile==NULL ){//bad filenameg_log.Write( LOG_FAILURE, "Could not load %s\n", szFilename );return false;}//allocate the memory for our height datam_heightData.m_ucpData= new unsigned char [iSize*iSize];//check to see if memory was successfully allocatedif( m_heightData.m_ucpData==NULL ){//the memory could not be allocated something is seriously wrong hereg_log.Write( LOG_FAILURE, "Could not allocate memory for%s\n", szFilename );return false;}//read the heightmap into contextfread( m_heightData.m_ucpData, 1, iSize*iSize, pFile );//Close the filefclose( pFile );//set the m_iSize datam_iSize= iSize;//yahoo! The heightmap has been successfully loadedg_log.Write( LOG_SUCCESS, "Loaded %s\n", szFilename );return true;
}//--------------------------------------------------------------
// Name:            CTERRAIN::SaveHeightMap - public
// Description:     Save a grayscale RAW height map
// Arguments:       -szFilename: the file name of the height map
// Return Value:    A boolean value: -true: successful save
//                                   -false: unsuccessful save
//--------------------------------------------------------------
bool CTERRAIN::SaveHeightMap( char* szFilename )
{FILE* pFile;//open a file to write topFile= fopen( szFilename, "wb" );if( pFile==NULL ){//bad filenameg_log.Write( LOG_FAILURE, "Could not create %s\n", szFilename );return false;}//check to see if our height map actually has data in itif( m_heightData.m_ucpData==NULL ){//something is seriously wrong hereg_log.Write( LOG_FAILURE, "The height data buffer for %s is empty\n", szFilename );return false;}//write the data to the filefwrite( m_heightData.m_ucpData, 1, m_iSize*m_iSize, pFile );//Close the filefclose( pFile );//w00t w00t! The heightmap has been successfully savedg_log.Write( LOG_SUCCESS, "Saved %s\n", szFilename );return true;
}//--------------------------------------------------------------
// Name:            CTERRAIN::UnloadHeightMap - public
// Description:     Unload the class's height map (if there is one)
// Arguments:       None
// Return Value:    A boolean value: -true: successful load
//                                   -false: unsuccessful load
//--------------------------------------------------------------
bool CTERRAIN::UnloadHeightMap( void )
{//check to see if the data has been setif( m_heightData.m_ucpData ){//delete the datadelete[] m_heightData.m_ucpData;//reset the map dimensions alsom_iSize= 0;}//the height map has been unloadedg_log.Write( LOG_SUCCESS, "Successfully unloaded the height map\n" );return true;
}//--------------------------------------------------------------
// Name:            CTERRAIN::NormalizeTerrain - private
// Description:     Scale the terrain height values to a range of
//                  0-255
// Arguments:       -fpHeightData: the height data buffer
// Return Value:    None
//--------------------------------------------------------------
void CTERRAIN::NormalizeTerrain( float* fpHeightData )
{float fMin, fMax;float fHeight;int i;fMin= fpHeightData[0];fMax= fpHeightData[0];//find the min/max values of the height fTempBufferfor( i=1; i<m_iSize*m_iSize; i++ ){if( fpHeightData[i]>fMax ) fMax= fpHeightData[i];else if( fpHeightData[i]<fMin ) fMin= fpHeightData[i];}//find the range of the altitudeif( fMax<=fMin )return;fHeight= fMax-fMin;//scale the values to a range of 0-255 (because I like things that way)for( i=0; i<m_iSize*m_iSize; i++ )fpHeightData[i]= ( ( fpHeightData[i]-fMin )/fHeight )*255.0f;
}//--------------------------------------------------------------
// Name:            CTERRAIN::FilterHeightBand - private
// Description:     Apply the erosion filter to an individual
//                  band of height values
// Arguments:       -fpBand: the band to be filtered
//                  -iStride: how far to advance per pass
//                  -iCount: Number of passes to make
//                  -fFilter: the filter strength
// Return Value:    None
//--------------------------------------------------------------
void CTERRAIN::FilterHeightBand( float* fpBand, int iStride, int iCount, float fFilter )
{float v= fpBand[0];int j  = iStride;int i;//go through the height band and apply the erosion filterfor( i=0; i<iCount-1; i++ ){fpBand[j]= fFilter*v + ( 1-fFilter )*fpBand[j];v = fpBand[j];j+= iStride;}
}//--------------------------------------------------------------
// Name:            CTERRAIN::FilterHeightfTempBuffer - private
// Description:     Apply the erosion filter to an entire buffer
//                  of height values
// Arguments:       -fpHeightData: the height values to be filtered
//                  -fFilter: the filter strength
// Return Value:    None
//--------------------------------------------------------------
void CTERRAIN::FilterHeightField( float* fpHeightData, float fFilter )
{int i;//erode left to rightfor( i=0; i<m_iSize; i++ )FilterHeightBand( &fpHeightData[m_iSize*i], 1, m_iSize, fFilter );//erode right to leftfor( i=0; i<m_iSize; i++ )FilterHeightBand( &fpHeightData[m_iSize*i+m_iSize-1], -1, m_iSize, fFilter );//erode top to bottomfor( i=0; i<m_iSize; i++ )FilterHeightBand( &fpHeightData[i], m_iSize, m_iSize, fFilter);//erode from bottom to topfor( i=0; i<m_iSize; i++ )FilterHeightBand( &fpHeightData[m_iSize*(m_iSize-1)+i], -m_iSize, m_iSize, fFilter );
}//--------------------------------------------------------------
// Name:            CTERRAIN::MakeTerrainFault - public
// Description:     Create a height data set using the "Fault Formation"
//                  algorithm.  Thanks a lot to Jason Shankel for this code!
// Arguments:       -iSize: Desired size of the height map
//                  -iIterations: Number of detail passes to make
//                  -iMinDelta, iMaxDelta: the desired min/max heights
//                  -iIterationsPerFilter: Number of passes per filter
//                  -fFilter: Strength of the filter
// Return Value:    A boolean value: -true: successful creation
//                                   -false: unsuccessful creation
//--------------------------------------------------------------
bool CTERRAIN::MakeTerrainFault( int iSize, int iIterations, int iMinDelta, int iMaxDelta, float fFilter )
{float* fTempBuffer;int iCurrentIteration;int iHeight;int iRandX1, iRandZ1;int iRandX2, iRandZ2;int iDirX1, iDirZ1;int iDirX2, iDirZ2;int x, z;int i;if( m_heightData.m_ucpData )UnloadHeightMap( );m_iSize= iSize;//allocate the memory for our height datam_heightData.m_ucpData= new unsigned char [m_iSize*m_iSize];fTempBuffer= new float [m_iSize*m_iSize];//check to see if memory was successfully allocatedif( m_heightData.m_ucpData==NULL ){//something is seriously wrong hereg_log.Write( LOG_FAILURE, "Could not allocate memory for height map" );return false;}//check to see if memory was successfully allocatedif( fTempBuffer==NULL ){//something is seriously wrong hereg_log.Write( LOG_FAILURE, "Could not allocate memory for height map" );return false;}//clear the height fTempBufferfor( i=0; i<m_iSize*m_iSize; i++ )fTempBuffer[i]= 0;for( iCurrentIteration=0; iCurrentIteration<iIterations; iCurrentIteration++ ){//calculate the height range (linear interpolation from iMaxDelta to//iMinDelta) for this fault-passiHeight= iMaxDelta - ( ( iMaxDelta-iMinDelta )*iCurrentIteration )/iIterations;//pick two points at random from the entire height mapiRandX1= rand( )%m_iSize;iRandZ1= rand( )%m_iSize;//check to make sure that the points are not the samedo{iRandX2= rand( )%m_iSize;iRandZ2= rand( )%m_iSize;} while ( iRandX2==iRandX1 && iRandZ2==iRandZ1 );//iDirX1, iDirZ1 is a vector going the same direction as the lineiDirX1= iRandX2-iRandX1;iDirZ1= iRandZ2-iRandZ1;for( z=0; z<m_iSize; z++ ){for( x=0; x<m_iSize; x++ ){//iDirX2, iDirZ2 is a vector from iRandX1, iRandZ1 to the current point (in the loop)iDirX2= x-iRandX1;iDirZ2= z-iRandZ1;//if the result of ( iDirX2*iDirZ1 - iDirX1*iDirZ2 ) is "up" (above 0), //then raise this point by iHeightif( ( iDirX2*iDirZ1 - iDirX1*iDirZ2 )>0 )fTempBuffer[( z*m_iSize )+x]+= ( float )iHeight;}}//erode terrainFilterHeightField( fTempBuffer, fFilter );}//normalize the terrain for our purposesNormalizeTerrain( fTempBuffer );//transfer the terrain into our class's unsigned char height bufferfor( z=0; z<m_iSize; z++ ){for( x=0; x<m_iSize; x++ )SetHeightAtPoint( ( unsigned char )fTempBuffer[( z*m_iSize )+x], x, z );}//delete temporary bufferif( fTempBuffer ){//delete the datadelete[] fTempBuffer;}return true;
}//--------------------------------------------------------------
// Name:            CTERRAIN::MakeTerrainPlasma - public
// Description:     Create a height data set using the "Midpoint
//                  Displacement" algorithm.  Thanks a lot to
//                  Jason Shankel for this code!
//                  Note: this algorithm has limited use, since
//                  CLOD algorithms usually require a height map
//                  size of (n^2)+1 x (n^2)+1, and this algorithm
//                  can only generate (n^2) x (n^2) maps
// Arguments:       -iSize: Desired size of the height map
//                  -fRoughness: Desired roughness of the created map
// Return Value:    A boolean value: -true: successful creation
//                                   -false: unsuccessful creation
//--------------------------------------------------------------
bool CTERRAIN::MakeTerrainPlasma( int iSize, float fRoughness )
{float* fTempBuffer;float fHeight, fHeightReducer;int iRectSize= iSize;int ni, nj;int mi, mj;int pmi, pmj;int i, j;int x, z;if( m_heightData.m_ucpData )UnloadHeightMap( );if( fRoughness<0 )fRoughness*= -1;fHeight         = ( float )iRectSize/2;fHeightReducer= ( float )pow(2, -1*fRoughness);m_iSize= iSize;//allocate the memory for our height datam_heightData.m_ucpData= new unsigned char [m_iSize*m_iSize];fTempBuffer= new float [m_iSize*m_iSize];memset(fTempBuffer,4.0,sizeof(float)*m_iSize*m_iSize);//check to see if memory was successfully allocatedif( m_heightData.m_ucpData==NULL ){//something is seriously wrong hereg_log.Write( LOG_FAILURE, "Could not allocate memory for height map" );return false;}//check to see if memory was successfully allocatedif( fTempBuffer==NULL ){//something is seriously wrong hereg_log.Write( LOG_FAILURE, "Could not allocate memory for height map" );return false;}//set the first value in the height fieldfTempBuffer[0]= 0.0f;//being the displacement processwhile( iRectSize>0 ){/*Diamond step -Find the values at the center of the retangles by averaging the values at the corners and adding a random offset:a.....b.     .  .  e  ..     .c.....d   e  = (a+b+c+d)/4 + randomIn the code below:a = (i,j)b = (ni,j)c = (i,nj)d = (ni,nj)e = (mi,mj)   */for( i=0; i<m_iSize; i+=iRectSize ){for( j=0; j<m_iSize; j+=iRectSize ){ni= ( i+iRectSize )%m_iSize;nj= ( j+iRectSize )%m_iSize;mi= ( i+iRectSize/2 );mj= ( j+iRectSize/2 );fTempBuffer[mi+mj*m_iSize]= ( float )( (fTempBuffer[i+j*m_iSize] + fTempBuffer[ni+j*m_iSize] + fTempBuffer[i+nj*m_iSize] + fTempBuffer[ni+nj*m_iSize] )/4 + RangedRandom( -fHeight/2, fHeight/2 ) );}}/*Square step -Find the values on the left and top sides of each rectangleThe right and bottom sides are the left and top sides of the neighboring rectangles,so we don't need to calculate themThe height m_heightData.m_ucpData wraps, so we're never left hanging.  The right side of the lastrectangle in a row is the left side of the first rectangle in the row.  The bottomside of the last rectangle in a column is the top side of the first rectangle inthe column........     ..     ..  d  ..     ..     .......a..g..b.     .     ..     .     ..  e  h  f  ..     .     ..     .     .......c......g = (d+f+a+b)/4 + randomh = (a+c+e+f)/4 + randomIn the code below:a = (i,j) b = (ni,j) c = (i,nj) d = (mi,pmj) e = (pmi,mj) f = (mi,mj) g = (mi,j)h = (i,mj)*/for( i=0; i<m_iSize; i+=iRectSize ){for( j=0; j<m_iSize; j+=iRectSize ){ni= (i+iRectSize)%m_iSize;nj= (j+iRectSize)%m_iSize;mi= (i+iRectSize/2);mj= (j+iRectSize/2);pmi= (i-iRectSize/2+m_iSize)%m_iSize;pmj= (j-iRectSize/2+m_iSize)%m_iSize;//Calculate the square value for the top side of the rectanglefTempBuffer[mi+j*m_iSize]= ( float )( ( fTempBuffer[i+j*m_iSize]     +fTempBuffer[ni+j*m_iSize]    +fTempBuffer[mi+pmj*m_iSize]      +fTempBuffer[mi+mj*m_iSize] )/4+RangedRandom( -fHeight/2, fHeight/2 ) );//Calculate the square value for the left side of the rectanglefTempBuffer[i+mj*m_iSize]= ( float )( ( fTempBuffer[i+j*m_iSize]   +fTempBuffer[i+nj*m_iSize]    +fTempBuffer[pmi+mj*m_iSize]      +fTempBuffer[mi+mj*m_iSize] )/4+ RangedRandom( -fHeight/2, fHeight/2 ) );}}//reduce the rectangle size by two to prepare for the next//displacement stageiRectSize/= 2;//reduce the height by the height reducerfHeight*= fHeightReducer;}//normalize the terrain for our purposesNormalizeTerrain( fTempBuffer );//transfer the terrain into our class's unsigned char height bufferfor( z=0; z<m_iSize; z++ ){for( x=0; x<m_iSize; x++ )SetHeightAtPoint( ( unsigned char )fTempBuffer[( z*m_iSize )+x], x, z );}//delete temporary bufferif( fTempBuffer ){//delete the datadelete[] fTempBuffer;}return true;
}