using SharpMath2;
using Microsoft.XNA.Framework;

var triangle1 = new Polygon2(new[] { new Vector2(0, 0), new Vector2(1, 1), new Vector2(2, 0) });
var triangle2 = ShapeUtils.CreateCircle(1, segments=3); // this is not the same triangle as triangle1, this will be equilateral
var octogon = ShapeUtils.CreateCircle(1, segments=8);

// Check intersection of two entities, both of which have the same triangle bounds but one is
// rotated at rotation1 and located at position1, where the other is rotated at rotation2 and 
// located at position2

var triangle = new Polygon2(new[] { new Vector2(0, 0), new Vector2(1, 1), new Vector2(2, 0) });

// Rotation2 caches Math.Sin and Math.Cos of the given angle, so if you know you are going to reuse
// rotations often (like 0) they should be cached (Rotation2.Zero is provided)
var rotation1 = Rotation2.Zero;
var rotation2 = Rotation2.Zero; // new Rotation2((float)(Math.PI / 6)) would be 30degrees
var position1 = new Vector2(5, 3);
var position2 = new Vector2(6, 3);

// Determine if the polygons overlap or touch: 
Polygon2.Intersects(triangle, triangle, position1, position2, rotation1, rotation2, false); // True

// Determine if the polygons overlap
Polygon2.Intersects(triangle, triangle, position1, position2, rotation1, rotation2, true); // False

// Note that in the special case of no rotation (rotation1 == rotation2 == Rotation2.Zero) we can
// use the shorter function definition by omitting the rotation parameters
Polygon2.Intersects(triangle, triangle, position1, position2, true); // False

// Suppose we have two entities, entity1 and entity2, both of which use the polygon "triangle" and are at position1, rotation1 and 
// position2, rotation2 respectively. If we are updating entity1 and we want to detect and handle collision with entity2 we would
// do:

// note we do not check for intersection first - while intersection is faster to check than intersection + MTV, it is not 
// faster to check intersection then intersection + MTV if you will need the MTV.

// Note strict is not an option for MTV - if two triangles are touching but not overlapping then
// it doesn't make sense to try and get an MTV
Tuple<Vector2, float> mtv = Polygon2.IntersectMTV(triangle, triangle, position1, position2, rotation1, rotation2);
if(mtv != null)
{
  // The two entites are colliding.
  position1 += mtv.Item1 * mtv.Item2;
  
  // Polygon2.Intersects(triangle, triangle, position1, position2, rotation1, rotation2, true); -> False
  // Polygon2.Intersects(triangle, triangle, position1, position2, rotation1, rotation2, false); -> True
}

var triangle = ShapeUtils.CreateCircle(1, segments=3);
var tile = new Rect2(0, 0, 1, 1); // minX, minY, maxX, maxY NOT x, y, w, h.

var triPos = new Vector2(3.3, 4.1);
var triRot = new Rotation2((float)(Math.PI / 6));

Vector2 tmp = Vector2.Zero; // Vector2 is a struct so this is safe
int xMin = (int)triPos.x;
int xMax = (int)Math.Ceiling(triPos.x + triangle.LongestAxisLength);
int yMin = (int)triPos.y;
int yMax = (int)Math.Ceiling(triPos.y + triangle.LongestAxisLength);
for(int y = yMin; y <= yMax; y++)
{
  tmp.Y = y;
  for(int x = xMin; x <= xMax; x++) 
  {
     tmp.X = x;
     var intersectsTileAtXY = Shape2.Intersects(triangle, tile, triPos, tmp, triRot, true);
     Console.Write($"({x},{y})={intersectsTileAtXY}")
     if(intersectsTileAtXY)
       Console.Write("  "); // true is 1 letter shorter than false
     else
       Console.Write(" ");
  }
  Console.WriteLine();
}

var complicatedShape = ShapeUtils.CreateCircle(5); // radius 5, 32 segments

// Note we are not providing rotation - rect2 does not support rotation 
// (use ShapeUtils.CreateRectangle for that, which returns a Polygon2)
Rect2.Intersects(complicatedShape.AABB, complicatedShape.AABB, Vector2.Zero, new Vector2(3, 0), true); // True

var circle = new Circle2(3); // The only argument is the radius of the circle.
var anotherCircle = new Circle2(5); 
var triangle = ShapeUtils.CreateCircle(2, segments=3); 

// Circle -> Circle collision using the same underlying circle object
Circle2.Intersects(circle, circle, Vector2.Zero, new Vector(1, 0), true); // True

// Circle -> Circle collision can be done using just the radius
Circle2.Intersects(3.0f, 3.0f, Vector2.Zero, new Vector2(1, 0), true); // Identical to above

// Circle -> Polygon collision must pass in a circle, not the radius of the circle
Shape2.Intersects(circle, triangle, Vector2.Zero, new Vector2(1, 1), true); // True

// Circle -> AABB collision
Shape2.Intersects(circle, triangle.AABB, Vector2.Zero, new Vector2(10, 0), true); // False