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AABB transform shortcut + sweep test

cosmonaut 2023-01-15 12:41:02 -08:00
parent b892da7749
commit 43aec46b2f
1 changed files with 100 additions and 4 deletions
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104
src/Collision/Fixed/AABB2D.cs
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@ -66,6 +66,8 @@ namespace MoonWorks.Collision.Fixed
);
}
static readonly Fix64 Half = Fix64.FromFraction(1, 2);
/// <summary>
/// Efficiently transforms the AABB by a Transform2D.
/// </summary>
@ -74,11 +76,42 @@ namespace MoonWorks.Collision.Fixed
/// <returns></returns>
public static AABB2D Transformed(AABB2D aabb, Transform2D transform)
{
var two = new Fix64(2);
var center = (aabb.Min + aabb.Max) / two;
var extent = (aabb.Max - aabb.Min) / two;
if (transform.IsAxisAligned)
{
var min = aabb.Min * transform.Scale + transform.Position;
var max = aabb.Max * transform.Scale + transform.Position;
var newCenter = Vector2.Transform(center, transform.TransformMatrix);
Fix64 minX, minY, maxX, maxY;
if (min.X <= max.X)
{
minX = min.X;
maxX = max.X;
}
else
{
minX = max.X;
maxX = min.X;
}
if (min.Y <= max.Y)
{
minY = min.Y;
maxY = max.Y;
}
else
{
minY = max.Y;
maxY = min.Y;
}
return new AABB2D(minX, minY, maxX, maxY);
}
var center = (aabb.Min + aabb.Max) * Half;
var extent = aabb.Max - center;
var newCenter = Vector2.Transform(center, transform.TransformMatrix);
var newExtent = Vector2.TransformNormal(extent, AbsoluteMatrix(transform.TransformMatrix));
return new AABB2D(newCenter - newExtent, newCenter + newExtent);
@ -152,6 +185,69 @@ namespace MoonWorks.Collision.Fixed
return a.Left < b.Right && a.Right > b.Left && a.Top < b.Bottom && a.Bottom > b.Top;
}
// FIXME: this is broken
public static bool SweepTest(AABB2D a, AABB2D b, Vector2 aMovement, Vector2 bMovement, out Fix64 normalizedTime)
{
if (TestOverlap(a, b))
{
normalizedTime = Fix64.Zero;
return true;
}
normalizedTime = Fix64.One;
var relativeVelocity = bMovement - aMovement;
Vector2 entry = Vector2.Zero;
if (a.Max.X < b.Min.X && relativeVelocity.X < 0)
{
entry.X = (a.Max.X - b.Min.X) / relativeVelocity.X;
}
else if (b.Max.X < a.Min.X && relativeVelocity.X > 0)
{
entry.X = (a.Min.X - b.Max.X) / relativeVelocity.X;
}
if (a.Max.Y < b.Min.Y && relativeVelocity.Y < 0)
{
entry.Y = (a.Max.Y - b.Min.Y) / relativeVelocity.Y;
}
else if (b.Max.Y > a.Min.Y && relativeVelocity.Y > 0)
{
entry.Y = (a.Min.Y - b.Max.Y) / relativeVelocity.Y;
}
Vector2 exit = new Vector2(Fix64.MaxValue, Fix64.MaxValue);
if (b.Max.X > a.Min.X && relativeVelocity.X < 0)
{
exit.X = (a.Min.X - b.Max.X) / relativeVelocity.X;
}
else if (a.Max.X > b.Min.X && relativeVelocity.X > 0)
{
exit.Y = (a.Max.X - b.Min.X) / relativeVelocity.X;
}
if (b.Max.Y > a.Min.Y && relativeVelocity.Y < 0)
{
exit.Y = (a.Min.Y - b.Max.Y) / relativeVelocity.Y;
}
else if (a.Max.Y > b.Min.Y && relativeVelocity.Y > 0)
{
exit.Y = (a.Max.Y - b.Min.Y) / relativeVelocity.Y;
}
Fix64 firstTime = Fix64.Max(entry.X, entry.Y);
Fix64 lastTime = Fix64.Min(exit.X, exit.Y);
if (firstTime <= lastTime && firstTime > 0)
{
normalizedTime = firstTime;
return true;
}
return false;
}
public override bool Equals(object obj)
{
return obj is AABB2D aabb && Equals(aabb);