DirectX - Removing UV Atlas Tool Seams

DirectX - Removing UV Atlas Tool Seams

I'm generating light maps for scene mesh objects using DirectX's UV Atlas
Tool( D3DXUVAtlasCreate() ). I've succeeded in generating an atlas,
however, when I try to render the mesh object using the atlas the seams
are visible on the mesh. Below are images of a lightmap generated for a
cube. The first things I noticed are the borders of the right and bottom
edges of the image...this my code to programatically create a texture(
image ) to represent the uv atlas is incorrect. Here is the code I use to
generate a uv atlas for a cube:
struct sVertexPosNormTex
{
D3DXVECTOR3 vPos, vNorm;
D3DXVECTOR2 vUV;
sVertexPosNormTex(){}
sVertexPosNormTex( D3DXVECTOR3 v, D3DXVECTOR3 n, D3DXVECTOR2 uv )
{
vPos = v;
vNorm = n;
vUV = uv;
}
~sVertexPosNormTex()
{
}
};
// create a light map texture to fill programatically
hr = D3DXCreateTexture( pd3dDevice, 128, 128, 1, 0, D3DFMT_A8R8G8B8,
D3DPOOL_MANAGED, &pLightmap );
if( FAILED( hr ) )
{
DebugStringDX( "Main", "Failed to D3DXCreateTexture( lightmap )",
__LINE__, hr );
return hr;
}
// get the zero level surface from the texture
IDirect3DSurface9 *pS = NULL;
pLightmap->GetSurfaceLevel( 0, &pS );
// clear surface
pd3dDevice->ColorFill( pS, NULL, D3DCOLOR_XRGB( 0, 0, 0 ) );
// load a sample mesh
DWORD dwcMaterials = 0;
LPD3DXBUFFER pMaterialBuffer = NULL;
V_RETURN( D3DXLoadMeshFromX( L"cube3.x", D3DXMESH_MANAGED, pd3dDevice,
&pAdjacency, &pMaterialBuffer, NULL, &dwcMaterials, &g_pMesh ) );
// generate adjacency
DWORD *pdwAdjacency = new DWORD[ 3 * g_pMesh->GetNumFaces() ];
g_pMesh->GenerateAdjacency( 1e-6f, pdwAdjacency );
// create light map coordinates
LPD3DXMESH pMesh = NULL;
LPD3DXBUFFER pFacePartitioning = NULL, pVertexRemapArray = NULL;
FLOAT resultStretch = 0;
UINT numCharts = 0;
hr = D3DXUVAtlasCreate( g_pMesh, 0, 0, 128, 128, 3.5f, 0,
pdwAdjacency, NULL, NULL, NULL, NULL, NULL, 0, &pMesh,
&pFacePartitioning, &pVertexRemapArray, &resultStretch, &numCharts );
if( SUCCEEDED( hr ) )
{
// release and set mesh
SAFE_RELEASE( g_pMesh );
g_pMesh = pMesh;
// write mesh to file
hr = D3DXSaveMeshToX( L"cube4.x",
g_pMesh,
0,
( const D3DXMATERIAL* )pMaterialBuffer->GetBufferPointer(),
NULL,
dwcMaterials,
D3DXF_FILEFORMAT_TEXT );
if( FAILED( hr ) )
{
DebugStringDX( "Main", "Failed to D3DXSaveMeshToX() at
OnD3D9CreateDevice()", __LINE__, hr );
}
// fill the the light map
hr = BuildLightmap( pS, g_pMesh );
if( FAILED( hr ) )
{
DebugStringDX( "Main", "Failed to BuildLightmap()", __LINE__,
hr );
}
}
else
{
DebugStringDX( "Main", "Failed to D3DXUVAtlasCreate() at
OnD3D9CreateDevice()", __LINE__, hr );
}
SAFE_RELEASE( pS );
SAFE_DELETE_ARRAY( pdwAdjacency );
SAFE_RELEASE( pFacePartitioning );
SAFE_RELEASE( pVertexRemapArray );
SAFE_RELEASE( pMaterialBuffer );
Here is code to fill lightmap texture:
HRESULT BuildLightmap( IDirect3DSurface9 *pS, LPD3DXMESH pMesh )
{
HRESULT hr = S_OK;
// validate lightmap texture surface and mesh
if( !pS
|| !pMesh )
return E_POINTER;
// lock the mesh vertex buffer
sVertexPosNormTex *pV = NULL;
pMesh->LockVertexBuffer( D3DLOCK_READONLY, ( void** )&pV );
// lock the mesh index buffer
WORD *pI = NULL;
pMesh->LockIndexBuffer( D3DLOCK_READONLY, ( void** )&pI );
// get the lightmap texture surface description
D3DSURFACE_DESC desc;
pS->GetDesc( &desc );
// lock the surface rect to fill with color data
D3DLOCKED_RECT rct;
hr = pS->LockRect( &rct, NULL, 0 );
if( FAILED( hr ) )
{
DebugStringDX( "main.cpp:", "Failed to
IDirect3DTexture9::LockRect()", __LINE__, hr );
return hr;
}
// iterate the pixels of the lightmap texture
// check each pixel to see if it lies between the uv coordinates
of a cube face
BYTE *pBuffer = ( BYTE* )rct.pBits;
for( UINT y = 0; y < desc.Height; ++y )
{
BYTE* pBufferRow = ( BYTE* )pBuffer;
for( UINT x = 0; x < desc.Width * 4; x+=4 )
{
// determine the pixel's uv coordinate
D3DXVECTOR2 p( ( ( float )x / 4.0f ) / ( float )desc.Width, y
/ ( float )desc.Height );
// for each face of the mesh
// check to see if the pixel lies within the face's uv
coordinates
for( UINT i = 0; i < 3 * pMesh->GetNumFaces(); i +=3 )
{
sVertexPosNormTex v[ 3 ];
v[ 0 ] = pV[ pI[ i + 0 ] ];
v[ 1 ] = pV[ pI[ i + 1 ] ];
v[ 2 ] = pV[ pI[ i + 2 ] ];
if( TexcoordIsWithinBounds( v[ 0 ].vUV, v[ 1 ].vUV, v[ 2
].vUV, p ) )
{
// the pixel lies b/t the uv coordinates of a cube face
// light contribution functions aren't needed yet
//D3DXVECTOR3 vPos = TexcoordToPos( v[ 0 ].vPos, v[ 1
].vPos, v[ 2 ].vPos, v[ 0 ].vUV, v[ 1 ].vUV, v[ 2
].vUV, p );
//D3DXVECTOR3 vNormal = v[ 0 ].vNorm;
// set the color of this pixel red( for demo )
BYTE ba[] = { 0, 0, 255, 255, };
//ComputeContribution( vPos, vNormal, g_sLight, ba );
// copy the byte array into the light map texture
memcpy( ( void* )&pBufferRow[ x ], ( void* )ba, 4 *
sizeof( BYTE ) );
}
}
}
// go to next line of the texture
pBuffer += rct.Pitch;
}
// unlock the surface rect
pS->UnlockRect();
// unlock mesh vertex and index buffers
pMesh->UnlockIndexBuffer();
pMesh->UnlockVertexBuffer();
// write the surface to file
hr = D3DXSaveSurfaceToFile( L"LightMap.jpg", D3DXIFF_JPG, pS, NULL,
NULL );
if( FAILED( hr ) )
DebugStringDX( "Main.cpp", "Failed to D3DXSaveSurfaceToFile()",
__LINE__, hr );
return hr;
}
bool TexcoordIsWithinBounds( const D3DXVECTOR2 &t0, const D3DXVECTOR2 &t1,
const D3DXVECTOR2 &t2,
const D3DXVECTOR2 &p )
{
// compute vectors
D3DXVECTOR2 v0 = t1 - t0,
v1 = t2 - t0,
v2 = p - t0;
float f00 = D3DXVec2Dot( &v0, &v0 );
float f01 = D3DXVec2Dot( &v0, &v1 );
float f02 = D3DXVec2Dot( &v0, &v2 );
float f11 = D3DXVec2Dot( &v1, &v1 );
float f12 = D3DXVec2Dot( &v1, &v2 );
// Compute barycentric coordinates
float invDenom = 1 / ( f00 * f11 - f01 * f01 );
float fU = ( f11 * f02 - f01 * f12 ) * invDenom;
float fV = ( f00 * f12 - f01 * f02 ) * invDenom;
// Check if point is in triangle
if( ( fU >= 0 ) && ( fV >= 0 ) && ( fU + fV < 1 ) )
return true;
return false;
}
Lightmap:

Screenshot:
It seems as though the lightmap texture that I generated with
BuildLightmap() requires an offset...how do I determine this offset?