// Detects any vector that is withing the vision range and returns it as a list
private List <Vector2> Vision(List <Collider> colliders)
{
List <Vector2> visibleVectors = new List <Vector2>();
// Create the vision vector
ahead = colliderPosition + Vector2.Normalize(velocity) * visionLength;
// Create an arc of 'detector points'
int degrees = (int)MathHelper.ToDegrees(visionAngle);
int stepSize = 15;
List <Vector2> detectorPoints = new List <Vector2>();
for (int i = -degrees; i < degrees; i += stepSize)
{
Vector2 point = Helper.RotateAroundOrigin(ahead, colliderPosition, MathHelper.ToRadians(i));
detectorPoints.Add(point);
DrawLater(() => spriteBatch.DrawPoint(point, Color.LightBlue, 5f));
}
// Go through every collider in this world
foreach (Collider collider in colliders)
{
if (collider.Equals(this))
{
continue; // You shouldn't be able to 'see' yourself
}
DrawLater(() => spriteBatch.DrawCircle(colliderPosition, visionLength, 180, Color.DarkBlue)); // DEBUG: How far we can see around us
if (!CircleCircleIntersect(colliderPosition, visionLength, collider.colliderPosition, collider.colliderRadius))
{
continue; // Collider is not in range of our vision 'collider'
}
// Check if a detector point intersects with the collider
// If so, we can add this detector point to the list of visible vectors
// TODO: It is not really a visible vector, you'd expect the collider to get added to the list... Maybe refactor this..
foreach (Vector2 detector in detectorPoints)
{
DrawLater(() => spriteBatch.DrawLine(colliderPosition, detector, Color.LightBlue)); // DEBUG: Draw a line to all detector points
CircleLineCollisionResult result = new CircleLineCollisionResult();
CircleLineCollide(collider.colliderPosition, collider.colliderRadius, colliderPosition, detector, ref result);
if (result.Collision)
{
DrawLater(() => spriteBatch.DrawPoint(detector, Color.Red, 5f)); // DEBUG: Show the detector point as red if he detects something
visibleVectors.Add(detector);
}
}
}
return(visibleVectors);
}
/// <summary>
/// Determines if a circle and line segment intersect, and if so, how they do.
/// </summary>
/// <param name="position">The center of the circle.</param>
/// <param name="radius">The radius of the circle.</param>
/// <param name="lineStart">The first point on the line segment.</param>
/// <param name="lineEnd">The second point on the line segment.</param>
/// <param name="result">The result data for the collision.</param>
/// <returns>True if a collision occurs, provided for convenience.</returns>
public static bool CircleLineCollide(Vector2 center, float radius,
Vector2 lineStart, Vector2 lineEnd, ref CircleLineCollisionResult result)
{
Vector2 AC = center - lineStart;
Vector2 AB = lineEnd - lineStart;
float ab2 = AB.LengthSquared();
if (ab2 <= 0f)
{
return(false);
}
float acab = Vector2.Dot(AC, AB);
float t = acab / ab2;
if (t < 0.0f)
{
t = 0.0f;
}
else if (t > 1.0f)
{
t = 1.0f;
}
result.Point = lineStart + t * AB;
result.Normal = center - result.Point;
float h2 = result.Normal.LengthSquared();
float r2 = radius * radius;
if (h2 > r2)
{
result.Collision = false;
}
else
{
result.Normal.Normalize();
result.Distance = (radius - (center - result.Point).Length());
result.Collision = true;
}
return(result.Collision);
}
/// <summary>
/// Determines if a circle and line segment intersect, and if so, how they do.
/// </summary>
/// <param name="center">The center of the circle.</param>
/// <param name="radius">The radius of the circle.</param>
/// <param name="rectangle">The rectangle.</param>
/// <param name="result">The result data for the collision.</param>
/// <returns>True if a collision occurs, provided for convenience.</returns>
public static bool CircleRectangleCollide(Vector2 center, float radius,
Rectangle rectangle, ref CircleLineCollisionResult result)
{
float xVal = center.X;
if (xVal < rectangle.Left)
{
xVal = rectangle.Left;
}
if (xVal > rectangle.Right)
{
xVal = rectangle.Right;
}
float yVal = center.Y;
if (yVal < rectangle.Top)
{
yVal = rectangle.Top;
}
if (yVal > rectangle.Bottom)
{
yVal = rectangle.Bottom;
}
Vector2 direction = new Vector2(center.X - xVal, center.Y - yVal);
float distance = direction.Length();
if ((distance > 0) && (distance < radius))
{
result.Collision = true;
result.Distance = radius - distance;
result.Normal = Vector2.Normalize(direction);
result.Point = new Vector2(xVal, yVal);
}
else
{
result.Collision = false;
}
return(result.Collision);
}
/// <summary>
/// Determines if a circle and line segment intersect, and if so, how they do.
/// </summary>
/// <param name="center">The center of the circle.</param>
/// <param name="radius">The radius of the circle.</param>
/// <param name="lineStart">The first point on the line segment.</param>
/// <param name="lineEnd">The second point on the line segment.</param>
/// <param name="result">The result data for the collision.</param>
/// <returns>True if a collision occurs, provided for convenience.</returns>
public static bool CircleLineCollide(Vector2 center, float radius,
Vector2 lineStart, Vector2 lineEnd, ref CircleLineCollisionResult result)
{
Vector2 AC = center - lineStart;
Vector2 AB = lineEnd - lineStart;
float ab2 = AB.LengthSquared();
if (ab2 <= 0f)
{
return false;
}
float acab = Vector2.Dot(AC, AB);
float t = acab / ab2;
if (t < 0.0f)
t = 0.0f;
else if (t > 1.0f)
t = 1.0f;
result.Point = lineStart + t * AB;
result.Normal = center - result.Point;
float h2 = result.Normal.LengthSquared();
float r2 = radius * radius;
if ((h2 > 0) && (h2 <= r2))
{
result.Normal.Normalize();
result.Distance = (radius - (center - result.Point).Length());
result.Collision = true;
}
else
{
result.Collision = false;
}
return result.Collision;
}
/// <summary>
/// Determines if a circle and a rectangle intersect, and if so, how they do.
/// </summary>
/// <param name="center">The center of the circle.</param>
/// <param name="radius">The radius of the circle.</param>
/// <param name="rectangle">The rectangle.</param>
/// <param name="result">The result data for the collision.</param>
/// <returns>True if a collision occurs, provided for convenience.</returns>
public static bool CircleRectangleCollide(Vector2 center, float radius,
Rectangle rectangle, ref CircleLineCollisionResult result)
{
float xVal = center.X;
if (xVal < rectangle.Left) xVal = rectangle.Left;
if (xVal > rectangle.Right) xVal = rectangle.Right;
float yVal = center.Y;
if (yVal < rectangle.Top) yVal = rectangle.Top;
if (yVal > rectangle.Bottom) yVal = rectangle.Bottom;
Vector2 direction = new Vector2(center.X - xVal, center.Y - yVal);
float distance = direction.Length();
if ((distance > 0) && (distance < radius))
{
result.Collision = true;
result.Distance = radius - distance;
result.Normal = Vector2.Normalize(direction);
result.Point = new Vector2(xVal, yVal);
}
else
{
result.Collision = false;
}
return result.Collision;
}
/// <summary>
/// Determines if a circle and a rectangle interset, and if so, how they do.
/// </summary>
/// <param name="center">The center of the circle.</param>
/// <param name="radius">The radius of the circle.</param>
/// <param name="rectangleCorners">Corner coordinates of the rectangle.</param>
/// <param name="result">The result data for the collision.</param>
/// <returns>True if a collision occurs, provided for convenience.</returns>
public static bool CircleRectangleCollide(Vector2 center, float radius,
Vector2[] rectangleCorners, ref CircleLineCollisionResult result)
{
return false;
}
