// This function calculates OBB to OBB colisions
public static CollisionInfo OBBToOBBCollision(CollisionHull2D a, CollisionHull2D b)
{
// Compute the R hat and U hat for both collision hulls
Vector2 ARHat = new Vector2(Mathf.Abs(Mathf.Cos(a.GetRotation())), Mathf.Abs(-Mathf.Sin(a.GetRotation())));
Vector2 BRHat = new Vector2(Mathf.Abs(Mathf.Cos(b.GetRotation())), Mathf.Abs(-Mathf.Sin(b.GetRotation())));
Vector2 AUHat = new Vector2(Mathf.Abs(Mathf.Sin(a.GetRotation())), Mathf.Abs(Mathf.Cos(a.GetRotation())));
Vector2 BUHat = new Vector2(Mathf.Abs(Mathf.Sin(b.GetRotation())), Mathf.Abs(Mathf.Cos(b.GetRotation())));
// Create a list of all penetrations on each axis
List <float> overlaps = new List <float>();
// Do axis checks
overlaps.Add(CheckOBBAxis(a, b, ARHat));
// Does the check pass?
if (overlaps[0] == Mathf.Infinity)
{
// If no, return nothing
return(null);
}
// Do axis checks
overlaps.Add(CheckOBBAxis(a, b, AUHat));
// Does the check pass?
if (overlaps[1] == Mathf.Infinity)
{
// If no, return nothing
return(null);
}
// Do axis checks
overlaps.Add(CheckOBBAxis(a, b, BRHat));
// Does the check pass?
if (overlaps[2] == Mathf.Infinity)
{
// If no, return nothing
return(null);
}
// Do axis checks
overlaps.Add(CheckOBBAxis(a, b, AUHat));
// Do the axis checks pass?
if (overlaps[3] != Mathf.Infinity)
{
// If yes, then inform the parents of the complex shape object (if applicable)
ReportCollisionToParent(a, b);
}
else
{
// If no, return nothing
return(null);
}
// Return full details of the Collision list if the two collide
return(new CollisionInfo(a, b, CollisionResolution.GetFinalPenetration(overlaps)));
}
// This function checks for a collision between two objects by projecting onto a specific axis
public static float CheckOBBAxis(CollisionHull2D shapeA, CollisionHull2D shapeB, Vector2 rotationAxis)
{
// Create a list of all points from the OBB hull for shape A
List <Vector2> shapeAPoints = new List <Vector2>();
shapeAPoints.Add(new Vector2(shapeA.GetPosition().x + shapeA.GetDimensions().x, shapeA.GetPosition().y + shapeA.GetDimensions().y));
shapeAPoints.Add(new Vector2(shapeA.GetPosition().x - shapeA.GetDimensions().x, shapeA.GetPosition().y - shapeA.GetDimensions().y));
shapeAPoints.Add(new Vector2(shapeA.GetPosition().x - shapeA.GetDimensions().x, shapeA.GetPosition().y + shapeA.GetDimensions().y));
shapeAPoints.Add(new Vector2(shapeA.GetPosition().x + shapeA.GetDimensions().x, shapeA.GetPosition().y - shapeA.GetDimensions().y));
// Create a list of all points from the OBB hull for shape B
List <Vector2> shapeBPoints = new List <Vector2>();
shapeBPoints.Add(new Vector2(shapeB.GetPosition().x + shapeB.GetDimensions().x, shapeB.GetPosition().y + shapeB.GetDimensions().y));
shapeBPoints.Add(new Vector2(shapeB.GetPosition().x - shapeB.GetDimensions().x, shapeB.GetPosition().y - shapeB.GetDimensions().y));
shapeBPoints.Add(new Vector2(shapeB.GetPosition().x - shapeB.GetDimensions().x, shapeB.GetPosition().y + shapeB.GetDimensions().y));
shapeBPoints.Add(new Vector2(shapeB.GetPosition().x + shapeB.GetDimensions().x, shapeB.GetPosition().y - shapeB.GetDimensions().y));
// Initialized shape minimums and maximums
float shapeAMin = Mathf.Infinity;
float shapeAMax = -Mathf.Infinity;
float shapeBMin = Mathf.Infinity;
float shapeBMax = -Mathf.Infinity;
// Set the total minimum and maximums
float totalMin;
float totalMax;
// Initialize all points for axis checks
for (int i = 0; i < shapeAPoints.Count; i++)
{
// Rotate original point
shapeAPoints[i] = new Vector2(Mathf.Cos(shapeA.GetRotation()) * (shapeAPoints[i].x - shapeA.GetPosition().x) - Mathf.Sin(shapeA.GetRotation()) * (shapeAPoints[i].y - shapeA.GetPosition().y) + shapeA.GetPosition().x,
Mathf.Sin(shapeA.GetRotation()) * (shapeAPoints[i].x - shapeA.GetPosition().x) + Mathf.Cos(shapeA.GetRotation()) * (shapeAPoints[i].y - shapeA.GetPosition().y) + shapeA.GetPosition().y);
// Project point
float temp = Vector2.Dot(shapeAPoints[i], rotationAxis);
// Is the point less than the minimum?
if (temp < shapeAMin)
{
// If yes, set it to the new minimum
shapeAMin = temp;
}
// Is the point greater than the maximum?
if (temp > shapeAMax)
{
// If yes, set it to the new maximum
shapeAMax = temp;
}
// Rotate original point
shapeBPoints[i] = new Vector2(Mathf.Cos(shapeB.GetRotation()) * (shapeBPoints[i].x - shapeB.GetPosition().x) - Mathf.Sin(shapeB.GetRotation()) * (shapeBPoints[i].y - shapeB.GetPosition().y) + shapeB.GetPosition().x,
Mathf.Sin(shapeB.GetRotation()) * (shapeBPoints[i].x - shapeB.GetPosition().x) + Mathf.Cos(shapeB.GetRotation()) * (shapeBPoints[i].y - shapeB.GetPosition().y) + shapeB.GetPosition().y);
// Project point
temp = Vector2.Dot(shapeBPoints[i], rotationAxis);
// Is the point less than the minimum?
if (temp < shapeBMin)
{
// If yes, set it to the new minimum
shapeBMin = temp;
}
// Is the point greater than the maximum
if (temp > shapeBMax)
{
// If yes, set it to the new maximum
shapeBMax = temp;
}
}
// Is the B shape min greater than the A shape maximum
if (shapeBMin > shapeAMin)
{
// If yes, set A to the new minimum
totalMin = shapeAMin;
}
else
{
// If no, set B to the new minimum
totalMin = shapeBMin;
}
// Is the A shape maximum greater than the B shape maximum
if (shapeBMax < shapeAMax)
{
// If yes, set A to the new maximum
totalMax = shapeAMax;
}
else
{
// If no, set B to the new maximum
totalMax = shapeBMax;
}
// Do axis checks
bool axisCheck = shapeAMin <= shapeBMax && shapeBMin <= shapeAMax;
// Does the check pass?
if (axisCheck)
{
// If yes, then return the penetration
return(totalMin - totalMax);
}
else
{
// If no, return nothing
return(Mathf.Infinity);
}
}
