private static bool Circle(CircleCollider a, CircleCollider b)
{
if ((a.Radius + b.Radius) > ((a.position + a.center) - (b.position + b.center)).Length())
{
return(true);
}
return(false);
}
public Bullet(float xPosition, float yPosition, float xDirection, float yDirection, float speed)
{
position = new Vector2(xPosition, yPosition);
direction = new Vector2(xDirection, yDirection);
this.speed = speed;
visual = new Sprite(Renderer.Instance.bullets, 32, 0, 32, 32);
collider = new CircleCollider(position.X, position.Y, 26, 15, 11);
}
// Finds the maximum and minimum values of a circle's projection onto an axis.
private static void GatherCircleProjectionExtents(Vector2 projectionAxis, CircleCollider circle, out float min, out float max)
{
// Project the circle's center onto the axis with a dot product.
float centerProjection = Vector2.Dot(circle.position + circle.center, projectionAxis);
// Add and subtract the radius to get the extents.
min = centerProjection - circle.Radius;
max = centerProjection + circle.Radius;
}
public BombPowerup(int xPosition, int yPosition)
{
position = new Vector2(xPosition, yPosition);
direction = new Vector2(-1, 0);
speed = 200;
visual = new AnimatedSprite(Renderer.Instance.powerup_bomb, 1, 8, 8, 1000, true);
collider = new CircleCollider(position.X, position.Y, 32, 32, 32);
}
public Bomb(int xPosition, int yPosition)
{
position = new Vector2(xPosition, yPosition);
visual = null;
collider = new CircleCollider(position.X, position.Y, 0, 0, 128);
AudioSystem.Instance.PlaySound("ui_back");
}
private static bool CircleHalfPlane(CircleCollider c, HalfPlaneCollider hp)
{
// Distance from the circle's center to the half-plane.
float distance = Math.Abs(hp.A * (c.position.X + c.center.X) + hp.B * (c.position.Y + c.center.Y) + hp.C) / (float)Math.Sqrt(hp.A * hp.A + hp.B * hp.B);
if (distance < c.Radius)
{
return(true);
}
return(false);
}
private static bool AABBCircle(AABBCollider a, CircleCollider c)
{
List <Vector2> AABBVerts = new List <Vector2>();
AABBVerts.Add(new Vector2(0, 0));
AABBVerts.Add(new Vector2(a.Width, 0));
AABBVerts.Add(new Vector2(a.Width, a.Height));
AABBVerts.Add(new Vector2(0, a.Height));
PolygonCollider hax = new PolygonCollider(a.position.X, a.position.Y, AABBVerts);
return(PolygonCircle(hax, c));
}
private static bool PolygonCircle(PolygonCollider p, CircleCollider c)
{
// Circle projection: project center, add and subtract radius.
// Circle - only one axis, runs from the center of the circle to the closest vertex on the polygon.
for (int i = 0; i < p.vertices.Count; i++)
{
// Get the axis to project the polygons' points onto.
Vector2 edge;
if (i != p.vertices.Count - 1)
{
edge = p.vertices[i + 1] - p.vertices[i];
}
else
{
edge = p.vertices[0] - p.vertices[i];
}
Vector2 axis = new Vector2(edge.Y, -edge.X); // Rotate the vector 90 degrees to get the axis vector. Rotation direction doesn't matter.
axis.Normalize(); // Normalize. It only needs to describe direction.
// Project each polygon onto the axis. Remember the extents (minimum and maximum) of each projection.
float aMin, aMax, bMin, bMax;
GatherPolygonProjectionExtents(axis, p.vertices, out aMin, out aMax);
GatherCircleProjectionExtents(axis, c, out bMin, out bMax);
// Test for overlap between the two projections.
if (aMin > bMax)
{
return(false);
}
if (aMax < bMin)
{
return(false);
}
}
// When checking against a circle we are interested in only one axis.
// It goes from the center of the circle to the closest vertex of the polygon.
// We need to find the closest vertex.
Vector2 closestVertex = p.vertices[0];
float distance = (c.position - closestVertex).LengthSquared(); // We can use squared length.
for (int i = 0; i < p.vertices.Count; i++)
{
float dist = p.vertices[i].LengthSquared();
if (dist < distance)
{
distance = dist;
closestVertex = p.vertices[i];
}
}
Vector2 circleEdge = closestVertex - c.position;
Vector2 circleAxis = new Vector2(circleEdge.Y, -circleEdge.X);
circleAxis.Normalize();
float caMin, caMax, cbMin, cbMax;
GatherPolygonProjectionExtents(circleAxis, p.vertices, out caMin, out caMax);
GatherCircleProjectionExtents(circleAxis, c, out cbMin, out cbMax);
if (caMin > cbMax)
{
return(false);
}
if (caMax < cbMin)
{
return(false);
}
return(true);
}
