/// <summary>
/// Determines if a circle and rectangle intersect.
/// </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>
/// <returns>Returns a <see cref="Vector2" /> representing the normal if a collision occurs; otherwise <c>null</c>.</returns>
public static Vector2? GetCircleRectangleCollisionNormal(Vector2 center, float radius, RectangleF rectangle)
{
var contact = center;
if (contact.X < rectangle.Left) contact.X = rectangle.Left;
if (contact.X > rectangle.Right) contact.X = rectangle.Right;
if (contact.Y < rectangle.Top) contact.Y = rectangle.Top;
if (contact.Y > rectangle.Bottom) contact.Y = rectangle.Bottom;
var v = new Vector2(contact.X - center.X, contact.Y - center.Y);
var length = v.Length();
return length > 0 && length < radius ? v/length : (Vector2?) null;
}
public virtual void DrawLine(Point2f start, Point2f end, Colorf color, float padding = 2.0f)
{
//draw line with start and end position
//padding means the width of line
//color.Alpha means the opacity of line
//first, we compute the matrix of world transform
var transform = new GuiTransform();
var vector = new System.Numerics.Vector2(end.X - start.X, end.Y - start.Y);
//1.compute the scale component, x-component is euqal the length of line, y-component is equal the padding
transform.World = Matrix4x4.CreateScale(vector.Length(), padding, 1.0f);
//2.compute the angle of rotate, we only rotate it at the z-axis
transform.World *= Matrix4x4.CreateRotationZ((float)Math.Atan2(vector.Y, vector.X), new System.Numerics.Vector3(0, padding * 0.5f, 0));
//3.compute the translation, the position of start, but the y is start.y - padding * 0.5f
transform.World *= Matrix4x4.CreateTranslation(new System.Numerics.Vector3(start.X, start.Y - padding * 0.5f, 0));
//4.keep transform matrix data
transform.World *= Transform;
//set project matrix
transform.Project = mProject;
//second, we set the render config
var renderConfig = new GuiRenderConfig()
{
Color = color, Config = new Vector4(0)
};
//update buffer
mTransformBuffer.Update(transform);
mRenderConfigBuffer.Update(renderConfig);
//set buffer and shader
mDevice.SetVertexBuffer(mSquareVertexBuffer);
mDevice.SetIndexBuffer(mSquareIndexBuffer);
mDevice.SetBuffer(mTransformBuffer, mTransformBufferSlot, GpuShaderType.All);
mDevice.SetBuffer(mRenderConfigBuffer, mRenderConfigBufferSlot, GpuShaderType.All);
//draw
mDevice.DrawIndexed(6, 0, 0);
}
private List <System.Numerics.Vector2> CalculatePoints(System.Numerics.Vector2 start, System.Numerics.Vector2 middle, System.Numerics.Vector2 end, int accuracy)
{
List <System.Numerics.Vector2> result = new List <System.Numerics.Vector2>();
if (Utilities.IsCollinear(start, middle, end))
{
result.Add(start);
result.Add(middle);
}
else
{
System.Numerics.Vector2 center = Utilities.CalculateCircleCenter(start, middle, end);
// Debug.Log($"{center:F6}, r={radius:F6}, A={Utilities.OsuPixelToScreenPoint(slider.SliderPoints[0]):F6}, B={Utilities.OsuPixelToScreenPoint(slider.SliderPoints[1]):F6}, C={Utilities.OsuPixelToScreenPoint(slider.SliderPoints[2]):F6}");
System.Numerics.Vector2 OA = new System.Numerics.Vector2(start.X - center.X, start.Y - center.Y);
System.Numerics.Vector2 OB = new System.Numerics.Vector2(middle.X - center.X, middle.Y - center.Y);
System.Numerics.Vector2 OC = new System.Numerics.Vector2(end.X - center.X, end.Y - center.Y);
float radius = OA.Length();
float angleCcwOaOb = Utilities.CalculateOrientedAngle(OA, OB);
if (angleCcwOaOb < 0)
{
angleCcwOaOb += 2 * (float)Math.PI;
}
float angleCcwOaOc = Utilities.CalculateOrientedAngle(OA, OC);
if (angleCcwOaOc < 0)
{
angleCcwOaOc += 2 * (float)Math.PI;
}
if (angleCcwOaOb > angleCcwOaOc)
{
angleCcwOaOc -= 2 * (float)Math.PI;
}
float segmentAngle = angleCcwOaOc / accuracy;
float currentAngle = Mathf.Atan2(OA.Y, OA.X);
for (int i = 0; i < accuracy; i++)
{
result.Add(new System.Numerics.Vector2(center.X + radius * Mathf.Cos(currentAngle), center.Y + radius * Mathf.Sin(currentAngle)));
currentAngle += segmentAngle;
}
}
return(result);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)] public static FLOAT Length(VECTOR v)
{
return(v.Length());
}
internal override void SolveVelocityConstraints(ref TimeStep step)
{
Body b = _bodyB;
XForm xf1;
b.GetXForm(out xf1);
Vector2 r = MathUtils.Multiply(ref xf1.R, _localAnchor - b.GetLocalCenter());
// Cdot = v + cross(w, r)
Vector2 Cdot = b._linearVelocity + MathUtils.Cross(b._angularVelocity, r);
Vector2 impulse = MathUtils.Multiply(ref _mass, -(Cdot + _beta * _C + _gamma * _impulse));
Vector2 oldImpulse = _impulse;
_impulse += impulse;
float maxImpulse = step.dt * _maxForce;
if (_impulse.LengthSquared() > maxImpulse * maxImpulse)
{
_impulse *= maxImpulse / _impulse.Length();
}
impulse = _impulse - oldImpulse;
b._linearVelocity += b._invMass * impulse;
b._angularVelocity += b._invI * MathUtils.Cross(r, impulse);
}