static Plane[] GetClipPlanesForDirectionalLightShadowGeneration( Camera camera,
RenderLight light, float farClipDistance)
{
float shadowFarDistance = SceneManager.Instance.ShadowFarDistance;
Frustum cameraFrustum = FrustumUtils.GetFrustumByCamera( camera, farClipDistance );
Vec3 cameraPosition = cameraFrustum.Origin;
Vec3 farCenterPoint;
{
float distance = shadowFarDistance;
//small border
distance *= 1.05f;
//not optimal
distance *= MathFunctions.Sqrt( 2 );
farCenterPoint = cameraPosition + cameraFrustum.Axis.Item0 * distance;
}
Vec3 pyramidCenter = ( cameraPosition + farCenterPoint ) * .5f;
Plane farPlane;
{
Vec3 normal = ( farCenterPoint - cameraPosition ).GetNormalize();
float distance = Vec3.Dot( normal, farCenterPoint );
farPlane = new Plane( normal, distance );
}
Vec3[] farCorners = new Vec3[ 4 ];
{
//4 - top-right far, 5 - top-left far, 6 - bottom-left far, 7 - bottom-right far.
Vec3[] points = camera.GetWorldSpaceCorners();
for( int n = 0; n < 4; n++ )
{
Ray ray = new Ray( cameraPosition, points[ n + 4 ] - cameraPosition );
float scale;
farPlane.RayIntersection( ray, out scale );
farCorners[ n ] = ray.GetPointOnRay( scale );
}
}
Vec3[] pyramidPoints = new Vec3[ 5 ];
{
pyramidPoints[ 0 ] = cameraPosition;
for( int n = 0; n < 4; n++ )
pyramidPoints[ n + 1 ] = farCorners[ n ];
}
Line[] pyramidEdges = new Line[ 8 ];
{
for( int n = 0; n < 4; n++ )
{
pyramidEdges[ n ] = new Line( cameraPosition, farCorners[ n ] );
pyramidEdges[ n + 4 ] = new Line( farCorners[ n ],
farCorners[ ( n + 1 ) % 4 ] );
}
}
List<Plane> clipPlanes = new List<Plane>( 7 );
{
Vec3 lightDirectionOffset = light.Direction * 10000.0f;
//back planes
{
if( farPlane.GetSide( farCenterPoint - lightDirectionOffset ) ==
Plane.Side.Negative )
{
clipPlanes.Add( farPlane );
}
for( int n = 0; n < 4; n++ )
{
Plane plane = Plane.FromPoints( cameraPosition, farCorners[ n ],
farCorners[ ( n + 1 ) % 4 ] );
if( plane.GetSide( cameraPosition - lightDirectionOffset ) ==
Plane.Side.Negative )
{
clipPlanes.Add( farPlane );
}
}
}
//generate edge planes
foreach( Line pyramidEdge in pyramidEdges )
{
Vec3 p1 = pyramidEdge.Start;
Vec3 p2 = pyramidEdge.End;
Vec3 p3 = p1 - lightDirectionOffset;
Plane plane;
{
plane = Plane.FromPoints( p1, p2, p3 );
if( plane.GetSide( pyramidCenter ) == Plane.Side.Positive )
plane = Plane.FromPoints( p2, p1, p3 );
}
bool existsPyramidPointsOnBothSides = false;
{
Plane.Side side = Plane.Side.No;
bool sideInitialized = false;
foreach( Vec3 pyramidPoint in pyramidPoints )
{
if( pyramidPoint.Equals( pyramidEdge.Start, .00001f ) )
continue;
if( pyramidPoint.Equals( pyramidEdge.End, .00001f ) )
continue;
Plane.Side s = plane.GetSide( pyramidPoint );
if( sideInitialized )
{
if( side == Plane.Side.Negative && s == Plane.Side.Positive ||
side == Plane.Side.Positive && s == Plane.Side.Negative )
{
existsPyramidPointsOnBothSides = true;
break;
}
}
else
{
side = s;
sideInitialized = true;
}
}
}
if( existsPyramidPointsOnBothSides )
continue;
clipPlanes.Add( plane );
}
}
return clipPlanes.ToArray();
}
