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Former-commit-id: f70a282d078d1fee3858ab7cd10952d5613cfe6c Former-commit-id: 07e613cc7879308b9475ee3a8582a9b5db3ff121 Former-commit-id: 73fdea9a14385d10b74a0abea0ece717170ec960af/merge-core
James Jackson-South
10 years ago
8 changed files with 343 additions and 70 deletions
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namespace ImageProcessor |
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{ |
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using System; |
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using System.Collections.Generic; |
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using System.Linq; |
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using System.Numerics; |
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/// <summary>
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/// A rotated rectangle. Adapted from the excellent sample. TODO: Refactor into a struct.
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/// <see href="http://www.xnadevelopment.com/tutorials/rotatedrectanglecollisions/rotatedrectanglecollisions.shtml"/>
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/// </summary>
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public class RotatedRectangle |
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{ |
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public Rectangle CollisionRectangle; |
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public float Rotation; |
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public Vector2 Origin; |
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public RotatedRectangle(Rectangle theRectangle, float theInitialRotation) |
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{ |
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CollisionRectangle = theRectangle; |
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Rotation = theInitialRotation; |
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//Calculate the Rectangles origin. We assume the center of the Rectangle will
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//be the point that we will be rotating around and we use that for the origin
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Origin = new Vector2((int)theRectangle.Width / 2f, (int)theRectangle.Height / 2f); |
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} |
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/// <summary>
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/// Used for changing the X and Y position of the RotatedRectangle
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/// </summary>
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/// <param name="theXPositionAdjustment"></param>
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/// <param name="theYPositionAdjustment"></param>
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public void ChangePosition(int theXPositionAdjustment, int theYPositionAdjustment) |
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{ |
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CollisionRectangle.X += theXPositionAdjustment; |
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CollisionRectangle.Y += theYPositionAdjustment; |
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} |
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/// <summary>
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/// Determines if the specfied point is contained within the rectangular region defined by
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/// this <see cref="RotatedRectangle"/>.
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/// </summary>
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/// <param name="x">The x-coordinate of the given point.</param>
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/// <param name="y">The y-coordinate of the given point.</param>
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/// <returns>The <see cref="bool"/></returns>
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public bool Contains(int x, int y) |
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{ |
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Rectangle rectangle = new Rectangle(x, y, 1, 1); |
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return this.Intersects(new RotatedRectangle(rectangle, 0.0f)); |
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} |
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/// <summary>
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/// This intersects method can be used to check a standard XNA framework Rectangle
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/// object and see if it collides with a Rotated Rectangle object
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/// </summary>
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/// <param name="rectangle"></param>
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/// <returns></returns>
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public bool Intersects(Rectangle rectangle) |
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{ |
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return this.Intersects(new RotatedRectangle(rectangle, 0.0f)); |
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} |
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/// <summary>
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/// Check to see if two Rotated Rectangls have collided
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/// </summary>
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/// <param name="theRectangle"></param>
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/// <returns></returns>
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public bool Intersects(RotatedRectangle theRectangle) |
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{ |
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//Calculate the Axis we will use to determine if a collision has occurred
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//Since the objects are rectangles, we only have to generate 4 Axis (2 for
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//each rectangle) since we know the other 2 on a rectangle are parallel.
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List<Vector2> aRectangleAxis = new List<Vector2> |
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{ |
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this.UpperRightCorner() - this.UpperLeftCorner(), |
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this.UpperRightCorner() - this.LowerRightCorner(), |
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theRectangle.UpperLeftCorner() - theRectangle.LowerLeftCorner(), |
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theRectangle.UpperLeftCorner() - theRectangle.UpperRightCorner() |
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}; |
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//Cycle through all of the Axis we need to check. If a collision does not occur
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//on ALL of the Axis, then a collision is NOT occurring. We can then exit out
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//immediately and notify the calling function that no collision was detected. If
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//a collision DOES occur on ALL of the Axis, then there is a collision occurring
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//between the rotated rectangles. We know this to be true by the Seperating Axis Theorem
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return aRectangleAxis.All(aAxis => this.IsAxisCollision(theRectangle, aAxis)); |
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} |
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/// <summary>
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/// Determines if a collision has occurred on an Axis of one of the
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/// planes parallel to the Rectangle
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/// </summary>
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/// <param name="theRectangle"></param>
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/// <param name="aAxis"></param>
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/// <returns></returns>
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private bool IsAxisCollision(RotatedRectangle theRectangle, Vector2 aAxis) |
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{ |
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//Project the corners of the Rectangle we are checking on to the Axis and
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//get a scalar value of that project we can then use for comparison
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List<int> aRectangleAScalars = new List<int> |
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{ |
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this.GenerateScalar(theRectangle.UpperLeftCorner(), aAxis), |
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this.GenerateScalar(theRectangle.UpperRightCorner(), aAxis), |
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this.GenerateScalar(theRectangle.LowerLeftCorner(), aAxis), |
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this.GenerateScalar(theRectangle.LowerRightCorner(), aAxis) |
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}; |
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//Project the corners of the current Rectangle on to the Axis and
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//get a scalar value of that project we can then use for comparison
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List<int> aRectangleBScalars = new List<int> |
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{ |
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this.GenerateScalar(this.UpperLeftCorner(), aAxis), |
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this.GenerateScalar(this.UpperRightCorner(), aAxis), |
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this.GenerateScalar(this.LowerLeftCorner(), aAxis), |
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this.GenerateScalar(this.LowerRightCorner(), aAxis) |
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}; |
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//Get the Maximum and Minium Scalar values for each of the Rectangles
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int aRectangleAMinimum = aRectangleAScalars.Min(); |
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int aRectangleAMaximum = aRectangleAScalars.Max(); |
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int aRectangleBMinimum = aRectangleBScalars.Min(); |
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int aRectangleBMaximum = aRectangleBScalars.Max(); |
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//If we have overlaps between the Rectangles (i.e. Min of B is less than Max of A)
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//then we are detecting a collision between the rectangles on this Axis
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if (aRectangleBMinimum <= aRectangleAMaximum && aRectangleBMaximum >= aRectangleAMaximum) |
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{ |
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return true; |
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} |
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else if (aRectangleAMinimum <= aRectangleBMaximum && aRectangleAMaximum >= aRectangleBMaximum) |
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{ |
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return true; |
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} |
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return false; |
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} |
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/// <summary>
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/// Generates a scalar value that can be used to compare where corners of
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/// a rectangle have been projected onto a particular axis.
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/// </summary>
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/// <param name="corner"></param>
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/// <param name="axis"></param>
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/// <returns></returns>
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private int GenerateScalar(Vector2 corner, Vector2 axis) |
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{ |
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// Using the formula for Vector projection. Take the corner being passed in
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// and project it onto the given Axis
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float numerator = Vector2.Dot(corner, axis); //(theRectangleCorner.X * theAxis.X) + (theRectangleCorner.Y * theAxis.Y);
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float denominator = Vector2.Dot(axis, axis); //(theAxis.X * theAxis.X) + (theAxis.Y * theAxis.Y);
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float aDivisionResult = numerator / denominator; |
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Vector2 projected = new Vector2(aDivisionResult * axis.X, aDivisionResult * axis.Y); |
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// Now that we have our projected Vector, calculate a scalar of that projection
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// that can be used to more easily do comparisons
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float scalar = Vector2.Dot(axis, projected); |
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return (int)scalar; |
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} |
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/// <summary>
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/// Rotate a point from a given location and adjust using the Origin we
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/// are rotating around
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/// </summary>
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/// <param name="thePoint"></param>
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/// <param name="theOrigin"></param>
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/// <param name="theRotation"></param>
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/// <returns></returns>
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private Vector2 RotatePoint(Vector2 thePoint, Vector2 theOrigin, float theRotation) |
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{ |
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Vector2 aTranslatedPoint = new Vector2 |
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{ |
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X = (float)(theOrigin.X |
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+ (thePoint.X - theOrigin.X) * Math.Cos(theRotation) |
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- (thePoint.Y - theOrigin.Y) * Math.Sin(theRotation)), |
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Y = (float)(theOrigin.Y |
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+ (thePoint.Y - theOrigin.Y) * Math.Cos(theRotation) |
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+ (thePoint.X - theOrigin.X) * Math.Sin(theRotation)) |
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}; |
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return aTranslatedPoint; |
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} |
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public Vector2 UpperLeftCorner() |
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{ |
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Vector2 aUpperLeft = new Vector2(this.CollisionRectangle.Left, this.CollisionRectangle.Top); |
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aUpperLeft = this.RotatePoint(aUpperLeft, aUpperLeft + this.Origin, this.Rotation); |
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return aUpperLeft; |
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} |
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public Vector2 UpperRightCorner() |
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{ |
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Vector2 aUpperRight = new Vector2(this.CollisionRectangle.Right, this.CollisionRectangle.Top); |
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aUpperRight = this.RotatePoint(aUpperRight, aUpperRight + new Vector2(-this.Origin.X, this.Origin.Y), this.Rotation); |
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return aUpperRight; |
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} |
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public Vector2 LowerLeftCorner() |
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{ |
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Vector2 aLowerLeft = new Vector2(this.CollisionRectangle.Left, this.CollisionRectangle.Bottom); |
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aLowerLeft = this.RotatePoint(aLowerLeft, aLowerLeft + new Vector2(this.Origin.X, -this.Origin.Y), this.Rotation); |
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return aLowerLeft; |
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} |
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public Vector2 LowerRightCorner() |
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{ |
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Vector2 aLowerRight = new Vector2(this.CollisionRectangle.Right, this.CollisionRectangle.Bottom); |
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aLowerRight = this.RotatePoint(aLowerRight, aLowerRight + new Vector2(-this.Origin.X, -this.Origin.Y), this.Rotation); |
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return aLowerRight; |
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} |
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public int X => this.CollisionRectangle.X; |
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public int Y => this.CollisionRectangle.Y; |
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public int Width => this.CollisionRectangle.Width; |
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public int Height => this.CollisionRectangle.Height; |
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} |
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} |
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