protected override void LoadContent()
{
debugDraw = new DebugDraw(GraphicsDevice);
box1 = new CollidableObject(new Vector2(50, 50))
{
Position = new Vector2(620, 250),
Velocity = new Vector2(20, 150),
Name = "Box",
};
int vertexCount = 10;
float radius = 150;
List <Vector2> vertices = new List <Vector2>();
for (int i = 0; i < vertexCount; i++)
{
float radians = i / (float)vertexCount * MathHelper.TwoPi;
var v = new Vector2(radius * (float)Math.Cos(radians), radius * (float)Math.Sin(radians));
vertices.Add(v);
}
//box2 = new CollidableObject(new Vector2(500, 25))
box2 = new CollidableObject(vertices)
{
Position = new Vector2(640, 500),
//Velocity = new Vector2(20, -50),
Name = "Object",
Velocity = new Vector2(0, -10),
};
}
private static bool FindIntervalIntersection(CollidableObject object1, CollidableObject object2, Vector2 velocity, Vector2 axis, out float time)
{
float min0, max0, min1, max1;
object1.CalculateInterval(axis, out min0, out max0);
object2.CalculateInterval(axis, out min1, out max1);
float d0 = min0 - max1;
float d1 = min1 - max0;
if (Utility.ApproximatelyZero(d0))
{
d0 = 0;
}
if (Utility.ApproximatelyZero(d1))
{
d1 = 0;
}
if (d0 < 0 && d1 < 0)
{
time = Math.Max(d0, d1);
return(true);
}
float v = Vector2.Dot(velocity, axis);
if (Utility.ApproximatelyZero(v))
{
time = float.NegativeInfinity;
return(false);
}
float t0 = -d0 / v;
float t1 = d1 / v;
if (t0 <= 0 && t1 <= 0)
{
time = float.NegativeInfinity;
return(false);
}
if (t0 > t1)
{
float temp = t0;
t0 = t1;
t1 = temp;
}
time = (t0 >= 0) ? t0 : t1;
if (time >= 1)
{
return(false);
}
return(true);
}
protected override void Update(GameTime gameTime)
{
base.Update(gameTime);
Vector2 newPosition = Vector2.Zero;
Vector2 newVelocity = Vector2.Zero;
var keyboardState = Keyboard.GetState();
if (keyboardState.IsKeyDown(Keys.Left))
{
newPosition.X = -1;
}
else if (keyboardState.IsKeyDown(Keys.Right))
{
newPosition.X = 1;
}
if (keyboardState.IsKeyDown(Keys.Up))
{
newPosition.Y = -1;
}
else if (keyboardState.IsKeyDown(Keys.Down))
{
newPosition.Y = 1;
}
if (keyboardState.IsKeyDown(Keys.A))
{
newVelocity.X = -1;
}
else if (keyboardState.IsKeyDown(Keys.D))
{
newVelocity.X = 1;
}
if (keyboardState.IsKeyDown(Keys.W))
{
newVelocity.Y = -1;
}
else if (keyboardState.IsKeyDown(Keys.S))
{
newVelocity.Y = 1;
}
if (keyboardState.IsKeyDown(Keys.P))
{
pauseRotation = true;
}
else if (keyboardState.IsKeyDown(Keys.U))
{
pauseRotation = false;
}
box1.Velocity += newVelocity;
box1.Position += newPosition;
if (!pauseRotation)
{
box1.Rotation += (float)gameTime.ElapsedGameTime.TotalSeconds;
box2.Rotation -= (float)gameTime.ElapsedGameTime.TotalSeconds / 2;
}
box1.UpdateWorldSpaceVertices();
box2.UpdateWorldSpaceVertices();
if (CollidableObject.FindCollision(box1, box2, out Vector2 axis, out float time))
{
box1.IsColliding = true;
box1.CollisionTime = time;
box1.PushVector = axis * -time;
box2.IsColliding = true;
box2.CollisionTime = Math.Max(time, 0);
box2.PushVector = axis;
}
public static bool FindCollision(CollidableObject object1, CollidableObject object2, out Vector2 axis, out float time)
{
Vector2 velocity = object1.Velocity - object2.Velocity;
axis = default(Vector2);
time = default(float);
Vector2 velocityNormal = Vector2.Normalize(new Vector2(velocity.Y, -velocity.X));
float tempTime;
// FIXME: if velocity magnitude is zero, we can skip this
// FIXME: maybe we should test this last, if we're overlapping it's not needed
if (!FindIntervalIntersection(object1, object2, velocity, velocityNormal, out tempTime))
{
return(false);
}
float maxNegativeTime = float.MinValue;
float maxPositiveTime = float.MinValue;
Vector2 maxNegativeAxis = Vector2.Zero;
Vector2 maxPositiveAxis = Vector2.Zero;
bool futureCollision = false;
foreach (var testAxis in object1.CollisionAxes)
{
if (!FindIntervalIntersection(object1, object2, velocity, testAxis, out tempTime))
{
return(false);
}
if (tempTime >= 0)
{
if (tempTime > maxPositiveTime)
{
maxPositiveTime = tempTime;
maxPositiveAxis = testAxis;
}
futureCollision = true;
}
else
{
if (tempTime > maxNegativeTime)
{
maxNegativeTime = tempTime;
maxNegativeAxis = testAxis;
}
}
}
foreach (var testAxis in object2.CollisionAxes)
{
if (!FindIntervalIntersection(object1, object2, velocity, testAxis, out tempTime))
{
return(false);
}
if (tempTime >= 0)
{
if (tempTime > maxPositiveTime)
{
maxPositiveTime = tempTime;
maxPositiveAxis = testAxis;
}
futureCollision = true;
}
else
{
if (tempTime > maxNegativeTime)
{
maxNegativeTime = tempTime;
maxNegativeAxis = testAxis;
}
}
}
if (futureCollision)
{
time = maxPositiveTime;
axis = maxPositiveAxis;
}
else
{
time = maxNegativeTime;
axis = maxNegativeAxis;
}
if (Vector2.Dot(object1.Position - object2.Position, axis) < 0.0f)
{
axis *= -1.0f;
}
return(true);
}
