private bool DoIntersection(Ray r, out float phi, out Point phit, out float thit)
{
phi = 0.0f;
phit = new Point();
thit = 0.0f;
// Transform _Ray_ to object space
Ray ray = WorldToObject.TransformRay(r);
// Compute quadratic cylinder coefficients
float A = ray.Direction.X * ray.Direction.X + ray.Direction.Y * ray.Direction.Y;
float B = 2 * (ray.Direction.X * ray.Origin.X + ray.Direction.Y * ray.Origin.Y);
float C = ray.Origin.X * ray.Origin.X + ray.Origin.Y * ray.Origin.Y - _radius * _radius;
// Solve quadratic equation for _t_ values
float t0, t1;
if (!MathUtility.TryQuadratic(A, B, C, out t0, out t1))
return false;
// Compute intersection distance along ray
if (t0 > ray.MaxT || t1 < ray.MinT)
return false;
thit = t0;
if (t0 < ray.MinT)
{
thit = t1;
if (thit > ray.MaxT)
return false;
}
// Compute cylinder hit point and $\phi$
phit = ray.Evaluate(thit);
phi = MathUtility.Atan2(phit.Y, phit.X);
if (phi < 0.0)
phi += 2.0f * MathUtility.Pi;
// Test cylinder intersection against clipping parameters
if (phit.Z < _zMin || phit.Z > _zMax || phi > _phiMax)
{
if (thit == t1) return false;
thit = t1;
if (t1 > ray.MaxT) return false;
// Compute cylinder hit point and $\phi$
phit = ray.Evaluate(thit);
phi = MathUtility.Atan2(phit.Y, phit.X);
if (phi < 0.0f) phi += 2.0f * MathUtility.Pi;
if (phit.Z < _zMin || phit.Z > _zMax || phi > _phiMax)
return false;
}
return true;
}
private bool DoIntersection(Ray r, out float phi, out float dist2, out Point phit, out float thit)
{
phi = dist2 = thit = 0;
phit = Point.Zero;
// Transform _Ray_ to object space
Ray ray = WorldToObject.TransformRay(r);
// Compute plane intersection for disk
if (Math.Abs(ray.Direction.Z) < 1e-7)
{
return(false);
}
thit = (_height - ray.Origin.Z) / ray.Direction.Z;
if (thit < ray.MinT || thit > ray.MaxT)
{
return(false);
}
// See if hit point is inside disk radii and $\phimax$
phit = ray.Evaluate(thit);
dist2 = phit.X * phit.X + phit.Y * phit.Y;
if (dist2 > _radius * _radius || dist2 < _innerRadius * _innerRadius)
{
return(false);
}
// Test disk $\phi$ value against $\phimax$
phi = MathUtility.Atan2(phit.Y, phit.X);
if (phi < 0)
{
phi += 2.0f * MathUtility.Pi;
}
if (phi > _phiMax)
{
return(false);
}
return(true);
}
public void UpdateCamera(GameTime gameTime)
{
if (_animation != null)
{
_animation.Update(this, gameTime);
if (_animation.Finished)
{
_animation = null;
}
}
var yaw = MathUtility.Atan2(_lookDirection.Y, _lookDirection.X);
var pitch = MathUtility.Lerp(
0,
-_pitchAngle,
_pitch);
var cameraHeight = MathUtility.Lerp(
0,
_defaultHeight,
_zoom);
float clampedPitch = pitch;
if (pitch > 0 && pitch < _pitchAngle)
{
clampedPitch = _pitchAngle;
}
else if (pitch < 0 && pitch > -_pitchAngle)
{
clampedPitch = -_pitchAngle;
}
var cameraToTerrainDirection = Vector3.Normalize(new Vector3(
MathUtility.Cos(yaw),
MathUtility.Sin(yaw),
MathUtility.Sin(clampedPitch)));
// Back up camera from terrain position.
var toCameraRay = new Ray(_terrainPosition, -cameraToTerrainDirection);
var plane = Plane.CreateFromVertices(
new Vector3(0, 0, cameraHeight),
new Vector3(0, 1, cameraHeight),
new Vector3(1, 0, cameraHeight));
var toCameraIntersectionDistance = toCameraRay.Intersects(ref plane).Value;
var newPosition = _terrainPosition - cameraToTerrainDirection * toCameraIntersectionDistance;
// Pitch - 0 means top-down view.
// Pitch between 0 and CameraPitch = Move camera position to match pitch.
// Pitch between CameraPitch and horizontal = Raise or lower target height.
var lookDirection = new Vector3(
MathUtility.Cos(yaw),
MathUtility.Sin(yaw),
MathUtility.Sin(pitch));
var targetPosition = newPosition + lookDirection;
_camera.View = Matrix4x4.CreateLookAt(
newPosition,
targetPosition,
Vector3.UnitZ);
}
private bool DoIntersection(Ray r, out float phi, out Point phit, out float thit)
{
phi = 0.0f;
phit = new Point();
thit = 0.0f;
// Transform _Ray_ to object space
Ray ray = WorldToObject.TransformRay(r);
// Compute quadratic sphere coefficients
float A = ray.Direction.X * ray.Direction.X + ray.Direction.Y * ray.Direction.Y +
ray.Direction.Z * ray.Direction.Z;
float B = 2 *
(ray.Direction.X * ray.Origin.X + ray.Direction.Y * ray.Origin.Y + ray.Direction.Z * ray.Origin.Z);
float C = ray.Origin.X * ray.Origin.X + ray.Origin.Y * ray.Origin.Y +
ray.Origin.Z * ray.Origin.Z - _radius * _radius;
// Solve quadratic equation for _t_ values
float t0, t1;
if (!MathUtility.TryQuadratic(A, B, C, out t0, out t1))
{
return(false);
}
// Compute intersection distance along ray
if (t0 > ray.MaxT || t1 < ray.MinT)
{
return(false);
}
thit = t0;
if (t0 < ray.MinT)
{
thit = t1;
if (thit > ray.MaxT)
{
return(false);
}
}
// Compute sphere hit position and $\phi$
phit = ray.Evaluate(thit);
if (phit.X == 0.0f && phit.Y == 0.0f)
{
phit.X = 1e-5f * _radius;
}
phi = MathUtility.Atan2(phit.Y, phit.X);
if (phi < 0.0f)
{
phi += 2.0f * MathUtility.Pi;
}
// Test sphere intersection against clipping parameters
if ((_zMin > -_radius && phit.Z < _zMin) ||
(_zMax < _radius && phit.Z > _zMax) || phi > _phiMax)
{
if (thit == t1)
{
return(false);
}
if (t1 > ray.MaxT)
{
return(false);
}
thit = t1;
// Compute sphere hit position and $\phi$
phit = ray.Evaluate(thit);
if (phit.X == 0.0f && phit.Y == 0.0f)
{
phit.X = 1e-5f * _radius;
}
phi = MathUtility.Atan2(phit.Y, phit.X);
if (phi < 0.0f)
{
phi += 2.0f * MathUtility.Pi;
}
if ((_zMin > -_radius && phit.Z < _zMin) ||
(_zMax < _radius && phit.Z > _zMax) || phi > _phiMax)
{
return(false);
}
}
return(true);
}
public static float SphericalPhi(Vector v)
{
float p = MathUtility.Atan2(v.Y, v.X);
return((p < 0.0f) ? p + 2.0f * MathUtility.Pi : p);
}
