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Add CollisionMesh container
Efficiently stores collision triangles
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‎Sources/GameMath/3D Types/3D Physics/3D Colliders/Triangles/CollisionMesh.swift‎

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/*
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* Copyright © 2025 Dustin Collins (Strega's Gate)
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* All Rights Reserved.
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*
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* http://stregasgate.com
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*/
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/// An optimized container for CollisionTriangles
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public final class CollisionMesh {
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@usableFromInline
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package struct Components {
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@usableFromInline
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package var positions: [Float]
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@usableFromInline
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package var normals: [Float]
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@usableFromInline
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package var attributes: [UInt64]
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package init(positions: [Float], normals: [Float], attributes: [UInt64]) {
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self.positions = positions
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self.normals = normals
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self.attributes = attributes
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}
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}
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@usableFromInline
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package struct TriangleIndices {
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@usableFromInline
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package let p1: Int
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@usableFromInline
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package let p2: Int
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@usableFromInline
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package let p3: Int
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@usableFromInline
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package let center: Int
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@usableFromInline
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package let normal: Int
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@usableFromInline
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package let faceNormal: Int
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@usableFromInline
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package let attributes: Int
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package init(p1: Int, p2: Int, p3: Int, center: Int, normal: Int, faceNormal: Int, attributes: Int) {
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self.p1 = p1
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self.p2 = p2
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self.p3 = p3
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self.center = center
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self.normal = normal
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self.faceNormal = faceNormal
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self.attributes = attributes
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}
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}
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@usableFromInline
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package var components: Components
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@usableFromInline
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package var indices: [TriangleIndices]
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@inlinable
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public var triangleCount: Int {
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return indices.count
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}
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public init(collisionTriangles triangles: [CollisionTriangle]) {
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assert(triangles.isEmpty == false)
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var positions: [Position3] = []
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var normals: [Direction3] = []
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var attributes: [UInt64] = []
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var indicies: [TriangleIndices] = []
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for triangle in triangles {
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func indexByAppendingValue<V: Equatable>(_ value: V, to array: inout [V]) -> Int {
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var arrayIndex: Int
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if let existingIndex = array.firstIndex(of: value) {
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arrayIndex = existingIndex
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}else{
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arrayIndex = array.count
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array.append(value)
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}
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return arrayIndex
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}
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let faceNormal = Direction3((triangle.p2 - triangle.p1).cross(triangle.p3 - triangle.p1)).normalized
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let center = (triangle.p1 + triangle.p2 + triangle.p3) / 3
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indicies.append(
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TriangleIndices(
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p1: indexByAppendingValue(triangle.p1, to: &positions) * 3,
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p2: indexByAppendingValue(triangle.p2, to: &positions) * 3,
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p3: indexByAppendingValue(triangle.p3, to: &positions) * 3,
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center: indexByAppendingValue(center, to: &positions) * 3,
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normal: indexByAppendingValue(triangle.normal, to: &normals) * 3,
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faceNormal: indexByAppendingValue(faceNormal, to: &normals) * 3,
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attributes: indexByAppendingValue(triangle.rawAttributes, to: &attributes)
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)
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)
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}
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self.components = Components(
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positions: positions.valuesArray(),
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normals: normals.valuesArray(),
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attributes: attributes
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)
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self.indices = indicies
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}
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package init(indices: [TriangleIndices], positions: [Float], normals: [Float], attributes: [UInt64]) {
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self.indices = indices
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self.components = Components(positions: positions, normals: normals, attributes: attributes)
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}
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public func generateCollisionTriangles() -> [CollisionTriangle] {
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var triangles: [CollisionTriangle] = []
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triangles.reserveCapacity(triangleCount)
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for index in 0 ..< triangleCount {
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self.withTriangle(atIndex: index) { triangle in
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triangles.append(
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CollisionTriangle(
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p1: triangle.p1,
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p2: triangle.p2,
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p3: triangle.p3,
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normal: triangle.faceNormal,
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rawAttributes: triangle.rawAttributes
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)
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)
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}
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}
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return triangles
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}
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}
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public extension CollisionMesh {
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struct Triangle<CollisionAttributes: CollisionAttributesGroup>: ~Copyable {
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@usableFromInline
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internal var mesh: CollisionMesh
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@usableFromInline
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internal let indices: TriangleIndices
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@inlinable
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public var p1: Position3 {
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let baseIndex = indices.p1
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let x = mesh.components.positions[baseIndex]
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let y = mesh.components.positions[baseIndex + 1]
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let z = mesh.components.positions[baseIndex + 2]
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return Position3(x, y, z)
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}
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@inlinable
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public var p2: Position3 {
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let baseIndex = indices.p2
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let x = mesh.components.positions[baseIndex]
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let y = mesh.components.positions[baseIndex + 1]
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let z = mesh.components.positions[baseIndex + 2]
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return Position3(x, y, z)
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}
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@inlinable
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public var p3: Position3 {
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let baseIndex = indices.p3
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let x = mesh.components.positions[baseIndex]
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let y = mesh.components.positions[baseIndex + 1]
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let z = mesh.components.positions[baseIndex + 2]
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return Position3(x, y, z)
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}
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@inlinable
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public var center: Position3 {
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let baseIndex = indices.center
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let x = mesh.components.positions[baseIndex]
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let y = mesh.components.positions[baseIndex + 1]
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let z = mesh.components.positions[baseIndex + 2]
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return Position3(x, y, z)
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}
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@inlinable
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public var normal: Direction3 {
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let baseIndex = indices.normal
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let x = mesh.components.normals[baseIndex]
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let y = mesh.components.normals[baseIndex + 1]
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let z = mesh.components.normals[baseIndex + 2]
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return Direction3(x, y, z)
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}
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@inlinable
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public var faceNormal: Direction3 {
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let baseIndex = indices.faceNormal
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let x = mesh.components.normals[baseIndex]
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let y = mesh.components.normals[baseIndex + 1]
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let z = mesh.components.normals[baseIndex + 2]
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return Direction3(x, y, z)
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}
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@inlinable
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public var attributes: CollisionAttributes {
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let rawValue = mesh.components.attributes[indices.attributes]
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return CollisionAttributes(rawValue: rawValue)
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}
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@inlinable
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public var rawAttributes: UInt64 {
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return mesh.components.attributes[indices.attributes]
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}
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@inlinable
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public var plane: Plane3D {
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return Plane3D(origin: center, normal: normal)
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}
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@usableFromInline
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internal init(mesh: CollisionMesh, triangleIndex: Int) {
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self.mesh = mesh
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self.indices = mesh.indices[triangleIndex]
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}
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}
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struct MutableTriangle<CollisionAttributes: CollisionAttributesGroup>: ~Copyable {
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@usableFromInline
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internal var mesh: CollisionMesh
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@usableFromInline
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internal let indices: TriangleIndices
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@inlinable
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public var p1: Position3 {
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get {
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let baseIndex = Int(indices.p1)
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let x = mesh.components.positions[baseIndex]
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let y = mesh.components.positions[baseIndex + 1]
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let z = mesh.components.positions[baseIndex + 2]
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return Position3(x, y, z)
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}
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nonmutating set {
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let baseIndex = Int(indices.p1)
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mesh.components.positions[baseIndex] = newValue.x
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mesh.components.positions[baseIndex + 1] = newValue.y
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mesh.components.positions[baseIndex + 2] = newValue.z
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}
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}
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@inlinable
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public var p2: Position3 {
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get {
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let baseIndex = Int(indices.p2)
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let x = mesh.components.positions[baseIndex]
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let y = mesh.components.positions[baseIndex + 1]
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let z = mesh.components.positions[baseIndex + 2]
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return Position3(x, y, z)
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}
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nonmutating set {
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let baseIndex = Int(indices.p2)
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mesh.components.positions[baseIndex] = newValue.x
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mesh.components.positions[baseIndex + 1] = newValue.y
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mesh.components.positions[baseIndex + 2] = newValue.z
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}
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}
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@inlinable
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public var p3: Position3 {
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get {
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let baseIndex = Int(indices.p3)
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let x = mesh.components.positions[baseIndex]
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let y = mesh.components.positions[baseIndex + 1]
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let z = mesh.components.positions[baseIndex + 2]
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return Position3(x, y, z)
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}
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nonmutating set {
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let baseIndex = Int(indices.p3)
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mesh.components.positions[baseIndex] = newValue.x
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mesh.components.positions[baseIndex + 1] = newValue.y
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mesh.components.positions[baseIndex + 2] = newValue.z
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}
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}
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@inlinable
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public var normal: Direction3 {
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get {
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let baseIndex = Int(indices.normal)
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let x = mesh.components.normals[baseIndex]
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let y = mesh.components.normals[baseIndex + 1]
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let z = mesh.components.normals[baseIndex + 2]
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return Direction3(x, y, z)
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}
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nonmutating set {
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let baseIndex = Int(indices.normal)
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mesh.components.normals[baseIndex] = newValue.x
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mesh.components.normals[baseIndex + 1] = newValue.y
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mesh.components.normals[baseIndex + 2] = newValue.z
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}
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}
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@inlinable
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public var attributes: CollisionAttributes {
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get {
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let rawValue = mesh.components.attributes[Int(indices.attributes)]
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return CollisionAttributes(rawValue: rawValue)
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}
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nonmutating set {
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mesh.components.attributes[Int(indices.attributes)] = newValue.rawValue
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}
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}
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@usableFromInline
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internal init(mesh: CollisionMesh, triangleIndex: Int) {
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self.mesh = mesh
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self.indices = mesh.indices[triangleIndex]
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}
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}
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}
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extension CollisionMesh {
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@inlinable
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public func withTriangle<A: CollisionAttributesGroup, ResultType>(
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atIndex index: Int,
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with attributesType: A.Type = BasicCollisionAttributes.self,
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_ provideTriangle: (_ triangle: borrowing Triangle<A>) -> ResultType
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) -> ResultType {
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let triangle = Triangle<A>(mesh: self, triangleIndex: index)
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let result = provideTriangle(triangle)
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return result
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}
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@inlinable
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public func editTriangle<A: CollisionAttributesGroup, ResultType>(
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atIndex index: Int,
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with attributesType: A.Type = BasicCollisionAttributes.self,
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_ editTriangle: (_ triangle: borrowing MutableTriangle<A>) -> ResultType
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) -> ResultType {
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let triangle = MutableTriangle<A>(mesh: self, triangleIndex: index)
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let result = editTriangle(triangle)
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return result
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}
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}

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