protected override bool TestCollisionVsOBB(OBB_2D other, out Collision collision)
{
collision = null;
// same as aabb
// multiply circle center by box world matrix inverse
//other.transform.worldToLocalMatrix
Matrix4x4 otherMat = other.transform.worldToLocalMatrix;
Vector2 minExtents = other.particle.position - other.halfWidths, maxExtents = other.particle.position + other.halfWidths;
Vector2 adjustedCenter = otherMat.MultiplyPoint3x4(new Vector3(particle.position.x, particle.position.y, 0));
adjustedCenter.x *= other.transform.localScale.x;
adjustedCenter.y *= other.transform.localScale.y;
adjustedCenter += (Vector2)other.transform.position;
//adjustedCenter += particle.position;
Vector2 closestPoint;
closestPoint.x = Mathf.Clamp(adjustedCenter.x, minExtents.x, maxExtents.x);
closestPoint.y = Mathf.Clamp(adjustedCenter.y, minExtents.y, maxExtents.y);
Vector2 deltaPos = adjustedCenter - closestPoint;
bool colliding = deltaPos.sqrMagnitude < radius * radius;
if (colliding)
{
collision = new Collision();
Vector2 relativeVelocity = particle.velocity - other.particle.velocity;
Vector2 relativePosition = particle.position - other.particle.position;
// 7.1.1 closing velocity
collision.closingVelocity = Vector3.Dot(relativeVelocity, relativePosition.normalized);
// assuming one point of contact
collision.contact[0].normal = deltaPos.normalized;
collision.contact[0].point = closestPoint;
collision.contact[0].restitution = .5f;
collision.contact[0].penetrationDepth = radius - deltaPos.magnitude;
collision.a = this;
collision.b = other;
collision.status = colliding;
collision.contactCount = 1;
}
return(colliding);
}
protected override bool TestCollisionVsOBB(OBB_2D other, out Collision collision)
{
collision = null;
// Code from Michael Zheng and Ben Strong, using with permission
// same as above twice
// find max extents of OBB, do ABB vs this box
// then, transform this box into OBB's space, find max extents, repeat
//1. create max and min extents of this particle
//2. max = (center.x + length/2, center.y + height/2)
//3. min = (center.x - length/2, center.y - height/2)
//4. create max and min extents of other particle
//4a. find all corner points of the box using length, height
//4b. rotate all points around its rotation https://www.gamefromscratch.com/post/2012/11/24/GameDev-math-recipes-Rotating-one-point-around-another-point.aspx
//4c. min = (min(x of all points), min(y of all points)) https://stackoverflow.com/questions/3231176/how-to-get-size-of-a-rotated-rectangle
//4d. max = (max(x of all points), max(y of all points)
//5. check if this_max.x > other_min.x and this_max.y > other_min.y
//6. check if other_max.x > this_min.x and other_max.y > this_min.y
//7. transform this center around the other's center using its transform matrix inverse
//8. transform each point of the aab by the other's transform matrix inverse
//8. find max and min extents of this by using Max(all points), Min(all points)
//5. check if new this_max.x > other_min.x and new this_max.y > other_min.y
//6. check if other_max.x > new this_min.x and other_max.y > new this_min.y
//9. if all checks are true, then collision check passes
bool check1, check2;
Vector2 thisMax, thisMin, otherMax, otherMin;
Vector2 p1, p2, p3, p4;
Vector2 otherPosition = other.particle.position;
float thisLength = halfWidths[0];
float thisHeight = halfWidths[1];
float otherLength = other.halfWidths[0];
float otherHeight = other.halfWidths[1];
//max and min of this position
thisMax = new Vector2(particle.position.x + thisLength, particle.position.y + thisHeight);
thisMin = new Vector2(particle.position.x - thisLength, particle.position.y - thisHeight);
//find max and min of other
//get all corner points and then rotate it
//p1 = rotatePoint(new Vector2(otherLength, otherHeight), other.rotation);
//p2 = rotatePoint(new Vector2(otherLength, -otherHeight), other.rotation);
//p3 = rotatePoint(new Vector2(-otherLength, -otherHeight), other.rotation);
//p4 = rotatePoint(new Vector2(-otherLength, otherHeight), other.rotation);
p1 = other.transform.worldToLocalMatrix * (new Vector2(otherLength, otherHeight));
p2 = other.transform.worldToLocalMatrix * (new Vector2(otherLength, -otherHeight));
p3 = other.transform.worldToLocalMatrix * (new Vector2(-otherLength, -otherHeight));
p4 = other.transform.worldToLocalMatrix * (new Vector2(-otherLength, otherHeight));
//find max of all points
otherMax = new Vector2(Mathf.Max(p1.x, p2.x, p3.x, p4.x) + otherPosition.x, Mathf.Max(p1.y, p2.y, p3.y, p4.y) + otherPosition.y);
otherMin = new Vector2(Mathf.Min(p1.x, p2.x, p3.x, p4.x) + otherPosition.x, Mathf.Min(p1.y, p2.y, p3.y, p4.y) + otherPosition.y);
check1 = (thisMax.x >= otherMin.x && thisMax.y >= otherMin.y) && (otherMax.x >= thisMin.x && otherMax.y >= thisMin.y);
if (!check1)
{
return(false);
}
//for each corner, move it relative to the box then transform by the world matrix inverse. Finally add position back
p1 = other.transform.worldToLocalMatrix * (new Vector2(particle.position.x + thisLength, particle.position.y + thisHeight) - otherPosition); //this one
p2 = other.transform.worldToLocalMatrix * (new Vector2(particle.position.x + thisLength, particle.position.y - thisHeight) - otherPosition);
p3 = other.transform.worldToLocalMatrix * (new Vector2(particle.position.x - thisLength, particle.position.y - thisHeight) - otherPosition);
p4 = other.transform.worldToLocalMatrix * (new Vector2(particle.position.x - thisLength, particle.position.y + thisHeight) - otherPosition);
p1 += otherPosition;
p2 += otherPosition;
p3 += otherPosition;
p4 += otherPosition;
//get the extremes for min and max
thisMax = new Vector2(Mathf.Max(p1.x, p2.x, p3.x, p4.x), Mathf.Max(p1.y, p2.y, p3.y, p4.y));
thisMin = new Vector2(Mathf.Min(p1.x, p2.x, p3.x, p4.x), Mathf.Min(p1.y, p2.y, p3.y, p4.y));
otherMax = new Vector2(otherPosition.x + otherLength, otherPosition.y + otherHeight);
otherMin = new Vector2(otherPosition.x - otherLength, otherPosition.y - otherHeight);
check2 = (thisMax.x >= otherMin.x && thisMax.y >= otherMin.y) && (otherMax.x >= thisMin.x && otherMax.y >= thisMin.y);
if (!check2)
{
return(false);
}
return(true);
}
protected override bool TestCollisionVsOBB(OBB_2D other, out Collision collision)
{
collision = null;
// Code from Michael Zheng and Ben Strong, using with permission
//Transform this into others space and do AABB vs OBB
//transform other into this space and do AABB vs OBB
//If both tests pass, collision occurs otherwise no collision
//1. do AABB check with this rotated around other
//2. find all corner points of this box using length and height
//3. rotate the points of this box with its rotation
//4. transform the points using the transform inverse of the other
//5. min = (min(x of all points), min(y of all points))
//6. max = (max(x of all points), max(y of all points)
//7. create max and min extents of other particle
//8. max = (center.x + length/2, center.y + height/2)
//9. min = (center.x - length/2, center.y - height/2)
//10. check if this_max.x > other_min.x and this_max.y > other_min.y
//11. check if other_max.x > this_min.x and other_max.y > this_min.y
//12. do AABB check with other rotated around this
//13. find all corner points of other box using length and height
//14. rotate the points of other box with its rotation
//15. transform the points using the transform inverse of this
//16. min = (min(x of all points), min(y of all points))
//17. max = (max(x of all points), max(y of all points)
//18. create max and min extents of this particle
//19. max = (center.x + length/2, center.y + height/2)
//20. min = (center.x - length/2, center.y - height/2)
//21. check if this_max.x > other_min.x and this_max.y > other_min.y
//22. check if other_max.x > this_min.x and other_max.y > this_min.y
bool check1, check2;
Vector2 thisMax, thisMin, otherMax, otherMin;
Vector2 p1, p2, p3, p4;
Vector2 otherPosition = other.particle.position;
float thisLength = halfWidths[0];
float thisHeight = halfWidths[1];
float otherLength = other.halfWidths[0];
float otherHeight = other.halfWidths[1];
//get all corner points and then rotate it
p1 = transform.worldToLocalMatrix * (new Vector2(thisLength, thisHeight));
p2 = transform.worldToLocalMatrix * (new Vector2(thisLength, -thisHeight));
p3 = transform.worldToLocalMatrix * (new Vector2(-thisLength, -thisHeight));
p4 = transform.worldToLocalMatrix * (new Vector2(-thisLength, thisHeight));
//for each corner, move it relative to the box then transform by the world matrix inverse. Finally add position back
p1 = other.transform.worldToLocalMatrix * (p1 + particle.position - otherPosition);
p2 = other.transform.worldToLocalMatrix * (p2 + particle.position - otherPosition);
p3 = other.transform.worldToLocalMatrix * (p3 + particle.position - otherPosition);
p4 = other.transform.worldToLocalMatrix * (p4 + particle.position - otherPosition);
p1 += otherPosition;
p2 += otherPosition;
p3 += otherPosition;
p4 += otherPosition;
thisMax = new Vector2(Mathf.Max(p1.x, p2.x, p3.x, p4.x), Mathf.Max(p1.y, p2.y, p3.y, p4.y));
thisMin = new Vector2(Mathf.Min(p1.x, p2.x, p3.x, p4.x), Mathf.Min(p1.y, p2.y, p3.y, p4.y));
otherMax = new Vector2(otherPosition.x + otherLength, otherPosition.y + otherHeight);
otherMin = new Vector2(otherPosition.x - otherLength, otherPosition.y - otherHeight);
check1 = (thisMax.x >= otherMin.x && thisMax.y >= otherMin.y) && (otherMax.x >= thisMin.x && otherMax.y >= thisMin.y);
if (!check1)
{
return(false);
}
//get all corner points and then rotate it
p1 = other.transform.worldToLocalMatrix * (new Vector2(otherLength, otherHeight));
p2 = other.transform.worldToLocalMatrix * (new Vector2(otherLength, -otherHeight));
p3 = other.transform.worldToLocalMatrix * (new Vector2(-otherLength, -otherHeight));
p4 = other.transform.worldToLocalMatrix * (new Vector2(-otherLength, otherHeight));
//for each corner, move it relative to the box then transform by the world matrix inverse. Finally add position back
p1 = transform.worldToLocalMatrix * (p1 + otherPosition - particle.position); //this
p2 = transform.worldToLocalMatrix * (p2 + otherPosition - particle.position);
p3 = transform.worldToLocalMatrix * (p3 + otherPosition - particle.position);
p4 = transform.worldToLocalMatrix * (p4 + otherPosition - particle.position);
p1 += particle.position;
p2 += particle.position;
p3 += particle.position;
p4 += particle.position;
otherMax = new Vector2(Mathf.Max(p1.x, p2.x, p3.x, p4.x), Mathf.Max(p1.y, p2.y, p3.y, p4.y));
otherMin = new Vector2(Mathf.Min(p1.x, p2.x, p3.x, p4.x), Mathf.Min(p1.y, p2.y, p3.y, p4.y));
thisMax = new Vector2(particle.position.x + thisLength, particle.position.y + thisHeight);
thisMin = new Vector2(particle.position.x - thisLength, particle.position.y - thisHeight);
check2 = (thisMax.x >= otherMin.x && thisMax.y >= otherMin.y) && (otherMax.x >= thisMin.x && otherMax.y >= thisMin.y);
if (!check2)
{
return(false);
}
return(true);
}
protected abstract bool TestCollisionVsOBB(OBB_2D other, out Collision collision);
