//--------------------------------------------------------------------------------------
// Checks for collision of a point with this collider.
// Param1: The point to test.
// Returns true if the point is within the collider, that includes touching its outer line,
// false otherwise.
//--------------------------------------------------------------------------------------
bool CircleCollider::CheckPointCollision(const XMFLOAT2& point) const
{
float squareRadius = GetRadius() * GetRadius();
float squareDistance = 0.0f;
XMStoreFloat(&squareDistance, XMVector2LengthSq(XMLoadFloat2(&GetCentre()) - XMLoadFloat2(&point)));
return squareRadius >= squareDistance;
}
//==============================================================
// GetSpan
//==============================================================
inline void tBox::GetSpan(tScalar & min,
tScalar & max,
const tVector3 & axis) const
{
tScalar s = Abs(Dot(axis, mTransform.orientation.mCols[0])) * (0.5f * mSideLengths.x);
tScalar u = Abs(Dot(axis, mTransform.orientation.mCols[1])) * (0.5f * mSideLengths.y);
tScalar d = Abs(Dot(axis, mTransform.orientation.mCols[2])) * (0.5f * mSideLengths.z);
tScalar r = s + u + d;
tScalar p = Dot(GetCentre(), axis);
min = p-r;
max = p+r;
}
//--------------------------------------------------------------------------------------
// Checks for collision of a line with this collider.
// Param1: The start point of the line.
// Param2: The end point of the line.
// Returns true if the line intersects with the collider, that includes touching it and
// being fully encompassed by it, false otherwise.
//--------------------------------------------------------------------------------------
bool CircleCollider::CheckLineCollision(const XMFLOAT2& lineStart, const XMFLOAT2& lineEnd) const
{
if(lineStart.x == lineEnd.x && lineStart.y == lineEnd.y)
{
// If the points are identical, check whether that shared point lies within the collider.
return CheckPointCollision(lineStart);
}
XMVECTOR lineSegment = XMLoadFloat2(&lineEnd) - XMLoadFloat2(&lineStart);
XMVECTOR startToCollider = XMLoadFloat2(&GetCentre()) - XMLoadFloat2(&lineStart);
float segmentLength = 0.0f;
XMStoreFloat(&segmentLength, XMVector2Length(lineSegment));
XMVECTOR normLineSegment = lineSegment / segmentLength;
float projection = 0.0f;
XMStoreFloat(&projection, XMVector2Dot(startToCollider, normLineSegment));
if((projection < 0.0f) || (projection > segmentLength))
{
// Projection is beyond the start or end point of the segment
return false;
}
// Get the projected point
XMVECTOR projectedPoint = XMLoadFloat2(&lineStart) + normLineSegment * projection;
// Check if the projected point lies within the radius of the collider
float squareRadius = GetRadius() * GetRadius();
float squareDistance = 0.0f;
XMStoreFloat(&squareDistance, XMVector2Dot(XMLoadFloat2(&GetCentre()) - projectedPoint, XMLoadFloat2(&GetCentre()) - projectedPoint));
return squareRadius >= squareDistance;
}
