public Color4 FindColourAtCollision(Collision collision)
{
Color4 result = Color4.Black;
foreach (Scene.Lights.LightBase light in scene.Lights.Where(l => Vector3.Dot(l.Position - collision.Position, collision.Normal) > 0))
{
Vector3 lightposition = light.Position;
Vector3 lightdirection = lightposition - collision.Position;
if (Vector3.Dot(lightdirection, collision.Normal) <= 0)
{
continue;
}
// test if the light source is obstructed
Ray lightRay = new Ray()
{
Direction = lightposition - collision.Position,
Position = collision.Position
};
if (!collider.TryGetCollision(lightRay, out IEnumerable <Collision> lightCollisions) || lightCollisions.Any(c => (c.Position - collision.Position).LengthSquared > lightdirection.LengthSquared))
{
lightdirection.Normalize();
float effectiveness = Vector3.Dot(lightdirection, collision.Normal);
double brightness = light.GetBrightnessAtPosition(collision.Position);
Color4 collisionColour = collision.Shape.GetColourAt(collision.Position);
result.R = (float)MathHelper.Clamp(collisionColour.R * brightness * effectiveness * light.Colour.R + result.R, 0, 1);
result.G = (float)MathHelper.Clamp(collisionColour.G * brightness * effectiveness * light.Colour.G + result.G, 0, 1);
result.B = (float)MathHelper.Clamp(collisionColour.B * brightness * effectiveness * light.Colour.B + result.B, 0, 1);
}
}
result.A = (float)(1 - collision.Material.Reflectiveness);
return(result);
}