/* Interpolation between two quaternions */
LPD3DRMQUATERNION WINAPI D3DRMQuaternionSlerp(LPD3DRMQUATERNION q, LPD3DRMQUATERNION a, LPD3DRMQUATERNION b, D3DVALUE alpha)
{
D3DVALUE dot, epsilon, temp, theta, u;
D3DVECTOR v1, v2;
dot = a->s * b->s + D3DRMVectorDotProduct(&a->v, &b->v);
epsilon = 1.0f;
temp = 1.0f - alpha;
u = alpha;
if (dot < 0.0)
{
epsilon = -1.0;
dot = -dot;
}
if( 1.0f - dot > 0.001f )
{
theta = acos(dot);
temp = sin(theta * temp) / sin(theta);
u = sin(theta * alpha) / sin(theta);
}
q->s = temp * a->s + epsilon * u * b->s;
D3DRMVectorScale(&v1, &a->v, temp);
D3DRMVectorScale(&v2, &b->v, epsilon * u);
D3DRMVectorAdd(&q->v, &v1, &v2);
return q;
}
// Calculate the normals for all the vertices of the patches of land.
void BoidsLand::gouraudShading( )
{
// Local buffer for storing the current patches details.
D3DRMVERTEX patchVertices[ 6 ];
D3DVECTOR averageNormal;
int faces;
// Iterate through the patches of land on the landscape.
for ( int row = 0; row < LAND_Z_SIZE; row++ )
{
for ( int col = 0; col < LAND_X_SIZE; col++ )
{
// Get the current state of the current vertex.
landMesh -> GetVertices( patchGroups[ 0 ][ row ][ col ],
0, 6, patchVertices );
// Recalculate the normals from vertices 0 & 3.
// Find the average of the face normals surrounding the vertex.
averageNormal.x = 0;
averageNormal.y = 0;
averageNormal.z = 0;
faces = 0;
// Working round in a clockwise direction -
// - starting from the current face.
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row ][ col ][ 1 ] );
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row ][ col ][ 0 ] );
faces += 2;
if ( row > 0 )
{
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row - 1 ][ col ][ 0 ] );
faces++;
}
if ( row > 0 && col > 0 )
{
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row - 1 ][ col - 1 ][ 1 ] );
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row - 1 ][ col - 1 ][ 0 ] );
faces += 2;
}
if ( col > 0 )
{
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row ][ col - 1 ][ 1 ] );
faces++;
}
averageNormal.x /= faces;
averageNormal.y /= faces;
averageNormal.z /= faces;
// Normalise the resultant vector.
D3DRMVectorNormalize( &averageNormal );
// Update the normal of vertex 0.
patchVertices[ 0 ].normal = averageNormal;
// Update the normal of vertex 3.
patchVertices[ 3 ].normal = averageNormal;
// Recalculate the normal from vertex 1.
// Find the average of the face normals surrounding the vertex.
averageNormal.x = 0;
averageNormal.y = 0;
averageNormal.z = 0;
faces = 0;
// Working round in a clockwise direction -
// - starting from the current face.
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row ][ col ][ 0 ] );
faces++;
if ( col > 0 )
{
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row ][ col - 1 ][ 1 ] );
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row ][ col - 1 ][ 0 ] );
faces += 2;
}
if ( col > 0 && ( ( row + 1 ) < LAND_Z_SIZE ) )
{
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row + 1 ][ col - 1 ][ 1 ] );
faces++;
}
if ( ( row + 1 ) < LAND_Z_SIZE )
{
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row + 1 ][ col ][ 0 ] );
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row + 1 ][ col ][ 1 ] );
faces += 2;
}
averageNormal.x /= faces;
averageNormal.y /= faces;
averageNormal.z /= faces;
// Normalise the resultant vector.
D3DRMVectorNormalize( &averageNormal );
// Update the normal of vertex 1.
patchVertices[ 1 ].normal = averageNormal;
// Recalculate the normals from vertices 2 & 4.
// Find the average of the face normals surrounding the vertex.
averageNormal.x = 0;
averageNormal.y = 0;
averageNormal.z = 0;
faces = 0;
// Working round in a clockwise direction -
// - starting from the current face.
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row ][ col ][ 1 ] );
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row ][ col ][ 0 ] );
faces += 2;
if ( ( row + 1 ) < LAND_Z_SIZE )
{
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row + 1 ][ col ][ 1 ] );
faces++;
}
if ( ( row + 1 ) < LAND_Z_SIZE && ( col + 1 ) < LAND_X_SIZE )
{
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row + 1 ][ col + 1 ][ 0 ] );
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row + 1 ][ col + 1 ][ 1 ] );
faces += 2;
}
if ( ( col + 1 ) < LAND_X_SIZE )
{
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row ][ col + 1 ][ 0 ] );
faces++;
}
averageNormal.x /= faces;
averageNormal.y /= faces;
averageNormal.z /= faces;
// Normalise the resultant vector.
D3DRMVectorNormalize( &averageNormal );
// Update the normal of vertex 2.
patchVertices[ 2 ].normal = averageNormal;
// Update the normal of vertex 4.
patchVertices[ 4 ].normal = averageNormal;
// Recalculate the normal from vertex 5.
// Find the average of the face normals surrounding the vertex.
averageNormal.x = 0;
averageNormal.y = 0;
averageNormal.z = 0;
faces = 0;
// Working round in a clockwise direction -
//- starting from the current face.
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row ][ col ][ 1 ] );
faces++;
if ( ( col + 1 ) < LAND_X_SIZE )
{
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row ][ col + 1 ][ 0 ] );
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row ][ col + 1 ][ 1 ] );
faces += 2;
}
if ( row > 0 && ( ( col + 1 ) < LAND_X_SIZE ) )
{
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row - 1 ][ col + 1 ][ 0 ] );
faces++;
}
if ( row > 0 )
{
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row - 1 ][ col ][ 1 ] );
D3DRMVectorAdd( &averageNormal, &averageNormal,
&patchFaceNormals[ row - 1 ][ col ][ 0 ] );
faces += 2;
}
averageNormal.x /= faces;
averageNormal.y /= faces;
averageNormal.z /= faces;
// Normalise the resultant vector.
D3DRMVectorNormalize( &averageNormal );
// Update the normal of vertex 5.
patchVertices[ 5 ].normal = averageNormal;
// Store the state of the current vertex.
landMesh -> SetVertices( patchGroups[ 0 ][ row ][ col ],
0, 6, patchVertices );
}
}
}
