public IntersectionDto(Model.Ray ray, IBasicShape shape, float distanceT)
{
Ray = ray;
Shape = shape;
DistanceT = distanceT;
TangentialIntersection = false;
RayOrigin = RaysOrigin.Normal;
}
/// <summary>
/// Return only the first hit after calculating all
/// possible intersections for all shapes in the scene.
/// </summary>
/// <remarks>
/// This method offers an efficiency compared to <see cref="CalculateIntersections"/>.
/// However if you need the intersections as well, then use <see cref="CalculateIntersections"/>
/// instead and call the extension method <see cref="IntersectionExtensionMethods.GetHit"/>.
/// </remarks>
public IntersectionDto CalculateHit(Model.Ray ray)
{
return((
from s in _shapes
from i in s.GetIntersections(ray)
where i.DistanceT > 0F
orderby i.DistanceT
select i
).FirstOrDefault());
}
private static bool IsPointInShadow(World scene, Vector4 point)
{
// Vector from the point back to the light source.
var v = scene.LightSource.Position - point;
var distance = v.Length();
var direction = Vector4.Normalize(v);
// Check for a "hit", within the world.
var r = new Model.Ray(point, direction);
var h = scene.CalculateHit(r);
// If got a hit, check where (at what distance),
// to determine whether point is in shadow.
return(h.HasValue && h.DistanceT < distance);
}
// NOTE: Notice below reference to the "acne" effect. This is a real rudimentary bootstrap
// of a "special effect". May consider abstracting an "effects engine" at some stage,
// But for now, just allowing for the effect, which is in essence a rounding error!
public static LightingDto CalculateColorWithPhongReflection(World scene, Model.Ray ray, bool useAcneEffect = false)
{
var hit = scene.CalculateHit(ray);
bool isInShadow = hit.HasValue && IsPointInShadow(scene, useAcneEffect ? hit.Position : hit.OverPosition);
var color = CalculateColorWithPhongReflection(
hit, scene.LightSource, isInShadow);
return(new LightingDto
{
Color = color,
Hit = hit,
IsInShadow = isInShadow
});
}
/// <summary>
/// Calculate intersections with all shapes in the scene. Result includes all intersections
/// for all shapes, with reference to the shape, ray and distanceT for each.
/// </summary>
public IEnumerable <IntersectionDto> CalculateIntersections(Model.Ray ray)
{
return(from shape in _shapes
from intersection in shape.GetIntersections(ray)
select intersection);
}
public void CalculateRay_AtPixelLocation(int pixelX, int pixelY)
{
_rayInstance = _cameraInstance.GetRay(pixelX, pixelY);
}
