//--------------------------------------------------------------
// Name: CGEOMIPMAPPING::RenderPatch - private
// Description: Render a patch of terrain
// Arguments: -PX, PZ: the patch location
// -bMultitex: use multitexturing or not
// -bDetail: render with a detail map or not
// Return Value: None
//--------------------------------------------------------------
void CGEOMIPMAPPING::RenderPatch( int PX, int PZ, bool bMultiTex, bool bDetail )
{
SGEOMM_NEIGHBOR patchNeighbor;
SGEOMM_NEIGHBOR fanNeighbor;
float fSize;
float fHalfSize;
float x, z;
int iPatch= GetPatchNumber( PX, PZ );
int iDivisor;
int iLOD;
//find out information about the patch to the current patch's left, if the patch is of a
//greater detail or there is no patch to the left, we can render the mid-left vertex
if( m_pPatches[GetPatchNumber( PX-1, PZ )].m_iLOD<=m_pPatches[iPatch].m_iLOD || PX==0 )
patchNeighbor.m_bLeft= true;
else
patchNeighbor.m_bLeft= false;
//find out about the upper patch
if( m_pPatches[GetPatchNumber( PX, PZ+1 )].m_iLOD<=m_pPatches[iPatch].m_iLOD || PZ==m_iNumPatchesPerSide )
patchNeighbor.m_bUp= true;
else
patchNeighbor.m_bUp= false;
//find out about the right patch
if( m_pPatches[GetPatchNumber( PX+1, PZ )].m_iLOD<=m_pPatches[iPatch].m_iLOD || PX==m_iNumPatchesPerSide )
patchNeighbor.m_bRight= true;
else
patchNeighbor.m_bRight= false;
//find out about the lower patch
if( m_pPatches[GetPatchNumber( PX, PZ-1 )].m_iLOD<=m_pPatches[iPatch].m_iLOD || PZ==0 )
patchNeighbor.m_bDown= true;
else
patchNeighbor.m_bDown= false;
//we need to determine the distance between each triangle-fan that
//we will be rendering
iLOD = m_pPatches[GetPatchNumber( PX, PZ )].m_iLOD+1;
fSize = ( float )m_iPatchSize;
iDivisor= m_iPatchSize-1;
//find out how many fan divisions we are going to have
while( --iLOD>-1 )
iDivisor= iDivisor>>1;
//the size between the center of each triangle fan
fSize/= iDivisor;
//half the size between the center of each triangle fan (this will be
//the size between each vertex)
fHalfSize= fSize/2.0f;
for( z=fHalfSize; ( ( int )( z+fHalfSize ) )<m_iPatchSize+1; z+=fSize )
{
for( x=fHalfSize; ( ( int )( x+fHalfSize ))<m_iPatchSize+1; x+=fSize )
{
//if this fan is in the left row, we may need to adjust it's rendering to
//prevent cracks
if( x==fHalfSize )
fanNeighbor.m_bLeft= patchNeighbor.m_bLeft;
else
fanNeighbor.m_bLeft= true;
//if this fan is in the bottom row, we may need to adjust it's rendering to
//prevent cracks
if( z==fHalfSize )
fanNeighbor.m_bDown= patchNeighbor.m_bDown;
else
fanNeighbor.m_bDown= true;
//if this fan is in the right row, we may need to adjust it's rendering to
//prevent cracks
if( x>=( m_iPatchSize-fHalfSize ) )
fanNeighbor.m_bRight= patchNeighbor.m_bRight;
else
fanNeighbor.m_bRight= true;
//if this fan is in the top row, we may need to adjust it's rendering to
//prevent cracks
if( z>=( m_iPatchSize-fHalfSize ) )
fanNeighbor.m_bUp= patchNeighbor.m_bUp;
else
fanNeighbor.m_bUp= true;
//render the triangle fan
RenderFan( ( PX*m_iPatchSize )+x, ( PZ*m_iPatchSize )+z,
fSize, fanNeighbor, bMultiTex, bDetail );
}
}
}
void GeoMipMapping::RenderPatch(int px, int pz)
{
SGEOMM_NEIGHBOR patchNeighbor;
SGEOMM_NEIGHBOR fanNeighbor;
float fSize = 0.0f;
float fHalfSize = 0.0f;
float z, x;
int iPatch = GetPatchNumber(px, pz);
int iDivisor = 0;
int iLOD = 0;
//左边的比较精细，所以不用管，直接可以绘制
if (m_pPatches[GetPatchNumber(px - 1, pz)].m_iLOD <= m_pPatches[iPatch].m_iLOD || px == 0)
patchNeighbor.m_bLeft = true; //可以绘制
else
patchNeighbor.m_bLeft = false; //不能绘制
if (m_pPatches[GetPatchNumber(px, pz + 1)].m_iLOD <= m_pPatches[iPatch].m_iLOD || pz == m_iNumPatchesPerSide)
patchNeighbor.m_bUp = true;
else
patchNeighbor.m_bUp = false;
if (m_pPatches[GetPatchNumber(px + 1, pz)].m_iLOD <= m_pPatches[iPatch].m_iLOD || px == m_iNumPatchesPerSide)
patchNeighbor.m_bRight = true;
else
patchNeighbor.m_bRight = false;
if (m_pPatches[GetPatchNumber(px, pz - 1)].m_iLOD <= m_pPatches[iPatch].m_iLOD || pz == 0)
patchNeighbor.m_bBottom = true;
else
patchNeighbor.m_bBottom = false;
fSize = (float)m_iPatchSize;
iDivisor = m_iPatchSize - 1;
iLOD = m_pPatches[iPatch].m_iLOD;
while (iLOD-- >= 0)
iDivisor >>= 1;
fSize /= iDivisor;
fHalfSize = fSize / 2.0f;
for (z = fHalfSize; ((int)z + fHalfSize ) < m_iPatchSize + 1; z += fSize)
{
for (x = fHalfSize; ((int)x + fHalfSize) < m_iPatchSize + 1; x += fSize)
{
if (x == fHalfSize)
fanNeighbor.m_bLeft = patchNeighbor.m_bLeft;
else
fanNeighbor.m_bLeft = true;
if (z == fHalfSize)
fanNeighbor.m_bBottom = patchNeighbor.m_bBottom;
else
fanNeighbor.m_bBottom = true;
if (x >= (m_iPatchSize - fHalfSize))
fanNeighbor.m_bRight = patchNeighbor.m_bRight;
else
fanNeighbor.m_bRight = true;
if (z >= (m_iPatchSize - fHalfSize))
fanNeighbor.m_bUp = patchNeighbor.m_bUp;
else
fanNeighbor.m_bUp = true;
RenderFan((px * m_iPatchSize) + x, (pz * m_iPatchSize) + z,
fSize, fanNeighbor);
}
}
}
