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[KT] Box2d - Make Box2d kotlin more idiomatic 1
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- Make `Vec2` and `Vec3` data classes, so we don't have to implement `clone`

- Make `Vec2.dot`, `Vec2.cross`, `Vec3.dot` and `Vec3.cross` infix functions.

- Make `add`, `mul`,... operator overloads.

PiperOrigin-RevId: 714173937
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@copybara-github
Googler authored and copybara-github committed Jan 10, 2025
1 parent 7e73071 commit 2c78761
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Showing 30 changed files with 297 additions and 380 deletions.
36 changes: 12 additions & 24 deletions samples/box2d/src/main/kotlin/idiomatic/commonMain/org/jbox2d/collision/AABB.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -28,41 +28,29 @@ import org.jbox2d.common.Vec2
import org.jbox2d.pooling.IWorldPool
import org.jbox2d.pooling.normal.DefaultWorldPool

/** An axis-aligned bounding box. */
class AABB {
/**
* An axis-aligned bounding box.
*
* @param lowerVertex Bottom left vertex of bounding box.
* @param upperVertex Top right vertex of bounding box.
*/
class AABB(lowerVertex: Vec2? = null, upperVertex: Vec2? = null) {
/** Bottom left vertex of bounding box. */
val lowerBound: Vec2
val lowerBound: Vec2 = lowerVertex?.copy() ?: Vec2()

/** Top right vertex of bounding box. */
val upperBound: Vec2
val upperBound: Vec2 = upperVertex?.copy() ?: Vec2()

val perimeter: Float
get() = 2.0f * (upperBound.x - lowerBound.x + upperBound.y - lowerBound.y)

/** Creates the default object, with vertices at 0,0 and 0,0. */
constructor() {
lowerBound = Vec2()
upperBound = Vec2()
}

/**
* Copies from the given object
*
* @param copy the object to copy from
*/
constructor(copy: AABB) : this(copy.lowerBound, copy.upperBound) {}

/**
* Creates an AABB object using the given bounding vertices.
*
* @param lowerVertex the bottom left vertex of the bounding box
* @param maxVertex the top right vertex of the bounding box
*/
constructor(lowerVertex: Vec2, upperVertex: Vec2) {
lowerBound = lowerVertex.clone() // clone to be safe
upperBound = upperVertex.clone()
}

/**
* Sets this object from the given object
*
Expand Down Expand Up @@ -96,7 +84,7 @@ class AABB {
* @return
*/
fun getCenter(): Vec2 {
val center = Vec2(lowerBound)
val center = lowerBound.copy()
center.addLocal(upperBound)
center.mulLocal(.5f)
return center
Expand All @@ -113,7 +101,7 @@ class AABB {
* @return
*/
fun getExtents(): Vec2 {
val center = Vec2(upperBound)
val center = upperBound.copy()
center.subLocal(lowerBound)
center.mulLocal(.5f)
return center
Expand Down Expand Up @@ -181,7 +169,7 @@ class AABB {
@Deprecated(
message =
"please use {@link #raycast(RayCastOutput, RayCastInput, IWorldPool)} for better performance",
replaceWith = ReplaceWith("raycast(RayCastOutput, RayCastInput, IWorldPool)")
replaceWith = ReplaceWith("raycast(RayCastOutput, RayCastInput, IWorldPool)"),
)
fun raycast(output: RayCastOutput, input: RayCastInput): Boolean =
raycast(output, input, DefaultWorldPool(4, 4))
Expand Down
76 changes: 38 additions & 38 deletions samples/box2d/src/main/kotlin/idiomatic/commonMain/org/jbox2d/collision/Collision.kt
View file
Original file line number Diff line number Diff line change
Expand Up @@ -85,7 +85,7 @@ class Collision(private val pool: IWorldPool) {
shapeB: Shape,
indexB: Int,
xfA: Transform,
xfB: Transform
xfB: Transform,
): Boolean {
input.proxyA.set(shapeA, indexA)
input.proxyB.set(shapeB, indexB)
Expand All @@ -112,7 +112,7 @@ class Collision(private val pool: IWorldPool) {
circle1: CircleShape,
xfA: Transform,
circle2: CircleShape,
xfB: Transform
xfB: Transform,
) {
manifold.pointCount = 0
// before inline:
Expand Down Expand Up @@ -159,7 +159,7 @@ class Collision(private val pool: IWorldPool) {
polygon: PolygonShape,
xfA: Transform,
circle: CircleShape,
xfB: Transform
xfB: Transform,
) {
manifold.pointCount = 0
// Vec2 v = circle.m_p;
Expand Down Expand Up @@ -342,7 +342,7 @@ class Collision(private val pool: IWorldPool) {
xf1: Transform,
edge1: Int,
poly2: PolygonShape,
xf2: Transform
xf2: Transform,
): Float {
@Suppress("UNUSED_VARIABLE") val count1 = poly1.count
val vertices1 = poly1.vertices
Expand Down Expand Up @@ -419,7 +419,7 @@ class Collision(private val pool: IWorldPool) {
poly1: PolygonShape,
xf1: Transform,
poly2: PolygonShape,
xf2: Transform
xf2: Transform,
) {
val count1 = poly1.count
val normals1 = poly1.normals
Expand Down Expand Up @@ -510,7 +510,7 @@ class Collision(private val pool: IWorldPool) {
xf1: Transform,
edge1: Int,
poly2: PolygonShape,
xf2: Transform
xf2: Transform,
) {
@Suppress("UNUSED_VARIABLE") val count1 = poly1.count
val normals1 = poly1.normals
Expand Down Expand Up @@ -590,7 +590,7 @@ class Collision(private val pool: IWorldPool) {
polyA: PolygonShape,
xfA: Transform,
polyB: PolygonShape,
xfB: Transform
xfB: Transform,
) {
// Find edge normal of max separation on A - return if separating axis is found
// Find edge normal of max separation on B - return if separation axis is found
Expand Down Expand Up @@ -727,7 +727,7 @@ class Collision(private val pool: IWorldPool) {
edgeA: EdgeShape,
xfA: Transform,
circleB: CircleShape,
xfB: Transform
xfB: Transform,
) {
manifold.pointCount = 0

Expand All @@ -740,8 +740,8 @@ class Collision(private val pool: IWorldPool) {
e.set(B).subLocal(A)

// Barycentric coordinates
val u = Vec2.dot(e, temp.set(B).subLocal(Q))
val v = Vec2.dot(e, temp.set(Q).subLocal(A))
val u = e dot temp.set(B).subLocal(Q)
val v = e dot temp.set(Q).subLocal(A)
val radius = edgeA.radius + circleB.radius

// ContactFeature cf;
Expand All @@ -751,7 +751,7 @@ class Collision(private val pool: IWorldPool) {
// Region A
if (v <= 0.0f) {
d.set(Q).subLocal(A)
val dd = Vec2.dot(d, d)
val dd = d dot d
if (dd > radius * radius) {
return
}
Expand All @@ -760,7 +760,7 @@ class Collision(private val pool: IWorldPool) {
if (edgeA.hasVertex0) {
val A1 = edgeA.vertex0
e1.set(A).subLocal(A1)
val u1 = Vec2.dot(e1, temp.set(A).subLocal(Q))
val u1 = e1 dot temp.set(A).subLocal(Q)

// Is the circle in Region AB of the previous edge?
if (u1 > 0.0f) {
Expand All @@ -782,7 +782,7 @@ class Collision(private val pool: IWorldPool) {
// Region B
if (u <= 0.0f) {
d.set(Q).subLocal(B)
val dd = Vec2.dot(d, d)
val dd = d dot d
if (dd > radius * radius) {
return
}
Expand All @@ -792,7 +792,7 @@ class Collision(private val pool: IWorldPool) {
val B2 = edgeA.vertex3
val e2 = e1
e2.set(B2).subLocal(B)
val v2 = Vec2.dot(e2, temp.set(Q).subLocal(B))
val v2 = e2 dot temp.set(Q).subLocal(B)

// Is the circle in Region AB of the next edge?
if (v2 > 0.0f) {
Expand All @@ -812,21 +812,21 @@ class Collision(private val pool: IWorldPool) {
}

// Region AB
val den = Vec2.dot(e, e)
val den = e dot e
// assert is not supported in KMP.
// assert(den > 0.0f)

// Vec2 P = (1.0f / den) * (u * A + v * B);
P.set(A).mulLocal(u).addLocal(temp.set(B).mulLocal(v))
P.mulLocal(1.0f / den)
d.set(Q).subLocal(P)
val dd = Vec2.dot(d, d)
val dd = d dot d
if (dd > radius * radius) {
return
}
n.x = -e.y
n.y = e.x
if (Vec2.dot(n, temp.set(Q).subLocal(A)) < 0.0f) {
if (n dot temp.set(Q).subLocal(A) < 0.0f) {
n.set(-n.x, -n.y)
}
n.normalize()
Expand All @@ -846,7 +846,7 @@ class Collision(private val pool: IWorldPool) {
edgeA: EdgeShape,
xfA: Transform,
polygonB: PolygonShape,
xfB: Transform
xfB: Transform,
) {
collider.collide(manifold, edgeA, xfA, polygonB, xfB)
}
Expand Down Expand Up @@ -890,15 +890,15 @@ class Collision(private val pool: IWorldPool) {
PERSIST_STATE,

/** point was removed in the update */
REMOVE_STATE
REMOVE_STATE,
}

/** This structure is used to keep track of the best separating axis. */
internal class EPAxis {
enum class Type {
UNKNOWN,
EDGE_A,
EDGE_B
EDGE_B,
}

var type: Type? = null
Expand Down Expand Up @@ -931,7 +931,7 @@ class Collision(private val pool: IWorldPool) {
enum class VertexType {
ISOLATED,
CONCAVE,
CONVEX
CONVEX,
}

val polygonB = TempPolygon()
Expand Down Expand Up @@ -970,7 +970,7 @@ class Collision(private val pool: IWorldPool) {
edgeA: EdgeShape,
xfA: Transform,
polygonB: PolygonShape,
xfB: Transform
xfB: Transform,
) {
Transform.mulTransToOutUnsafe(xfA, xfB, xf)
Transform.mulToOutUnsafe(xf, polygonB.centroid, centroidB)
Expand All @@ -985,7 +985,7 @@ class Collision(private val pool: IWorldPool) {
edge1.set(v2).subLocal(v1)
edge1.normalize()
normal1.set(edge1.y, -edge1.x)
val offset1 = Vec2.dot(normal1, temp.set(centroidB).subLocal(v1))
val offset1 = normal1 dot temp.set(centroidB).subLocal(v1)
var offset0 = 0.0f
var offset2 = 0.0f
var convex1 = false
Expand All @@ -996,17 +996,17 @@ class Collision(private val pool: IWorldPool) {
edge0.set(v1).subLocal(v0)
edge0.normalize()
normal0.set(edge0.y, -edge0.x)
convex1 = Vec2.cross(edge0, edge1) >= 0.0f
offset0 = Vec2.dot(normal0, temp.set(centroidB).subLocal(v0))
convex1 = edge0 cross edge1 >= 0.0f
offset0 = normal0 dot temp.set(centroidB).subLocal(v0)
}

// Is there a following edge?
if (hasVertex3) {
edge2.set(v3).subLocal(v2)
edge2.normalize()
normal2.set(edge2.y, -edge2.x)
convex2 = Vec2.cross(edge1, edge2) > 0.0f
offset2 = Vec2.dot(normal2, temp.set(centroidB).subLocal(v2))
convex2 = edge1 cross edge2 > 0.0f
offset2 = normal2 dot temp.set(centroidB).subLocal(v2)
}

// Determine front or back collision. Determine collision normal limits.
Expand Down Expand Up @@ -1211,9 +1211,9 @@ class Collision(private val pool: IWorldPool) {

// Search for the polygon normal that is most anti-parallel to the edge normal.
var bestIndex = 0
var bestValue = Vec2.dot(normal, this.polygonB.normals[0])
var bestValue = normal dot this.polygonB.normals[0]
for (i in 1 until this.polygonB.count) {
val value = Vec2.dot(normal, this.polygonB.normals[i])
val value = normal dot this.polygonB.normals[i]
if (value < bestValue) {
bestValue = value
bestIndex = i
Expand Down Expand Up @@ -1264,8 +1264,8 @@ class Collision(private val pool: IWorldPool) {
}
rf.sideNormal1.set(rf.normal.y, -rf.normal.x)
rf.sideNormal2.set(rf.sideNormal1).negateLocal()
rf.sideOffset1 = Vec2.dot(rf.sideNormal1, rf.v1)
rf.sideOffset2 = Vec2.dot(rf.sideNormal2, rf.v2)
rf.sideOffset1 = rf.sideNormal1 dot rf.v1
rf.sideOffset2 = rf.sideNormal2 dot rf.v2

// Clip incident edge against extruded edge1 side edges.
var np: Int = clipSegmentToLine(clipPoints1, ie, rf.sideNormal1, rf.sideOffset1, rf.i1)
Expand All @@ -1289,7 +1289,7 @@ class Collision(private val pool: IWorldPool) {
}
var pointCount = 0
for (i in 0 until Settings.MAX_MANIFOLD_POINTS) {
val separation: Float = Vec2.dot(rf.normal, temp.set(clipPoints2[i].v).subLocal(rf.v1))
val separation: Float = rf.normal dot temp.set(clipPoints2[i].v).subLocal(rf.v1)
if (separation <= radius) {
val cp = manifold.points[pointCount]
if (primaryAxis.type == EPAxis.Type.EDGE_A) {
Expand Down Expand Up @@ -1357,11 +1357,11 @@ class Collision(private val pool: IWorldPool) {

// Adjacency
if (n.x * perp.x + n.y * perp.y >= 0.0f) {
if (Vec2.dot(temp.set(n).subLocal(upperLimit), normal) < -Settings.ANGULAR_SLOP) {
if (temp.set(n).subLocal(upperLimit) dot normal < -Settings.ANGULAR_SLOP) {
continue
}
} else {
if (Vec2.dot(temp.set(n).subLocal(lowerLimit), normal) < -Settings.ANGULAR_SLOP) {
if (temp.set(n).subLocal(lowerLimit) dot normal < -Settings.ANGULAR_SLOP) {
continue
}
}
Expand Down Expand Up @@ -1395,7 +1395,7 @@ class Collision(private val pool: IWorldPool) {
state1: Array<PointState>,
state2: Array<PointState>,
manifold1: Manifold,
manifold2: Manifold
manifold2: Manifold,
) {
for (i in 0 until Settings.MAX_MANIFOLD_POINTS) {
state1[i] = PointState.NULL_STATE
Expand Down Expand Up @@ -1441,7 +1441,7 @@ class Collision(private val pool: IWorldPool) {
vIn: Array<ClipVertex>,
normal: Vec2,
offset: Float,
vertexIndexA: Int
vertexIndexA: Int,
): Int {

// Start with no output points
Expand All @@ -1452,8 +1452,8 @@ class Collision(private val pool: IWorldPool) {
val vIn1v = vIn1.v

// Calculate the distance of end points to the line
val distance0 = Vec2.dot(normal, vIn0v) - offset
val distance1 = Vec2.dot(normal, vIn1v) - offset
val distance0 = (normal dot vIn0v) - offset
val distance1 = (normal dot vIn1v) - offset

// If the points are behind the plane
if (distance0 <= 0.0f) {
Expand Down
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