sort out circle collision flip logic

echo/shape/Circle.hx

@@ -87,7 +87,7 @@ class Circle extends Shape implements Poolable {
  return false;
  }
 
- override inline function collides(s:Shape):Null<CollisionData> return s.collide_circle(this);
+ override inline function collides(s:Shape):Null<CollisionData> return s.collide_circle(this, true);
 
  override inline function collide_rect(r:Rect, flip:Bool = false):Null<CollisionData> return r.rect_and_circle(this, !flip);
 

echo/util/SAT.hx

@@ -344,8 +344,8 @@ class SAT {
  }
 
  // Vector from A to B
- var nx = flip ? c.x - r.x : r.x - c.x;
- var ny = flip ? c.y - r.y : r.y - c.y;
+ var nx = flip ? r.x - c.x : c.x - r.x;
+ var ny = flip ? r.y - c.y : c.y - r.y;
  // Closest point on A to center of B
  var cx = nx;
  var cy = ny;
@@ -506,7 +506,7 @@ class SAT {
  test1 = min1 - max2;
  test2 = min2 - max1;
 
- // Preform another test
+ // Preform another test // TODO: What is this test doing, exactly?
  if (test1 > 0 || test2 > 0) {
  col.put();
  return null;
@@ -529,7 +529,7 @@ class SAT {
 
  col.overlap = Math.abs(col.overlap);
 
- if (!flip) {
+ if (flip) {
  col.normal.negate();
  }
 
@@ -590,6 +590,8 @@ class SAT {
  col.sa = flip ? polygon2 : polygon1;
  col.sb = flip ? polygon1 : polygon2;
 
+ // collision normal is calculated as resolution for poly2, so we need to
+ // negate the normal if we are not flipping the collision check.
  if (!flip) {
  col.normal.negate();
  }

sample/state/OverlappingSpawnState.hx

@@ -20,31 +20,25 @@ class OverlappingSpawnState extends BaseState {
  rotation: 0,
  material: material,
  shape: {
- type: POLYGON,
+ type: CIRCLE,
  radius: 16,
- width: 16,
- height: 16,
- sides: 5,
  offset_y: 0,
  }
  });
  world.add(body);
 
- body = new Body({
- x: 200,
- y: 53,
- rotation: 0,
- material: material,
- shape: {
- type: POLYGON,
- radius: 10,
- width: 10,
- height: 10,
- sides: 5,
- offset_y: 0,
- }
- });
- world.add(body);
+ // body = new Body({
+ // x: 200,
+ // y: 53,
+ // rotation: 0,
+ // material: material,
+ // shape: {
+ // type: CIRCLE,
+ // radius: 12,
+ // offset_y: 0,
+ // }
+ // });
+ // world.add(body);
 
  // Add a Physics body at the bottom of the screen for the other Physics Bodies to stack on top of
  // This body has a mass of 0, so it acts as an immovable object
@@ -53,7 +47,7 @@ class OverlappingSpawnState extends BaseState {
  x: world.width / 5,
  y: world.height - 40,
  material: material,
- rotation: 5,
+ // rotation: 5,
  shape: {
  type: RECT,
  width: world.width,

sample/state/StaticState.hx

@@ -31,9 +31,8 @@ class StaticState extends BaseState {
  y: (world.height * 0.5) * Math.sin(i) + world.height * 0.5,
  material: static_material,
  shape: {
- // type: CIRCLE,
- // radius: Random.range(2, 4),
- type: RECT,
+ type: CIRCLE,
+ radius: Random.range(2, 4),
  width: Random.range(2, 4),
  height: Random.range(2, 4)
  }