76 lines
2.8 KiB
Swift
76 lines
2.8 KiB
Swift
import XCTest
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@testable import ForgeColor
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final class CurveTests: XCTestCase {
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// Default 2-point identity curve is a no-op.
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func testIdentityNoOp() {
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let c = Curve.identity
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for x: Float in [0, 0.1, 0.18, 0.5, 0.9, 1] {
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XCTAssertEqual(c.evaluate(x), x, accuracy: 1e-6)
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}
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}
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// Curve passes exactly through its control points.
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func testInterpolatesControlPoints() {
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let c = Curve(points: [
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.init(x: 0, y: 0),
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.init(x: 0.25, y: 0.4),
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.init(x: 0.75, y: 0.7),
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.init(x: 1, y: 1),
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])
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XCTAssertEqual(c.evaluate(0.25), 0.4, accuracy: 1e-5)
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XCTAssertEqual(c.evaluate(0.75), 0.7, accuracy: 1e-5)
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XCTAssertEqual(c.evaluate(0), 0, accuracy: 1e-5)
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XCTAssertEqual(c.evaluate(1), 1, accuracy: 1e-5)
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}
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// Monotonic control points -> monotonic output (no spline overshoot ringing).
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func testMonotonicPreserved() {
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let c = Curve(points: [
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.init(x: 0, y: 0),
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.init(x: 0.1, y: 0.5), // steep segment then flat — classic overshoot trap
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.init(x: 0.2, y: 0.55),
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.init(x: 1, y: 1),
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])
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var prev: Float = -1
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for i in 0...1000 {
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let y = c.evaluate(Float(i) / 1000)
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XCTAssertGreaterThanOrEqual(y, prev - 1e-6, "non-monotonic at x=\(Float(i) / 1000)")
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prev = y
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}
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}
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// Input outside domain pins to endpoint values.
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func testEndpointPinning() {
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let c = Curve(points: [.init(x: 0.2, y: 0.3), .init(x: 0.8, y: 0.9)])
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XCTAssertEqual(c.evaluate(0), 0.3, accuracy: 1e-6)
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XCTAssertEqual(c.evaluate(-5), 0.3, accuracy: 1e-6)
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XCTAssertEqual(c.evaluate(1), 0.9, accuracy: 1e-6)
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XCTAssertEqual(c.evaluate(99), 0.9, accuracy: 1e-6)
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}
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// Points auto-sorted by x.
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func testUnsortedPointsSorted() {
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let c = Curve(points: [.init(x: 1, y: 1), .init(x: 0, y: 0), .init(x: 0.5, y: 0.6)])
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XCTAssertEqual(c.evaluate(0.5), 0.6, accuracy: 1e-5)
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}
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// CurveSet: master applies to all channels, then per-channel.
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func testCurveSetMasterThenChannel() {
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var set = CurveSet.identity
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set.master = Curve(points: [.init(x: 0, y: 0), .init(x: 1, y: 0.5)]) // halve
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set.red = Curve(points: [.init(x: 0, y: 0.1), .init(x: 1, y: 1.1)]) // +0.1
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let out = set.apply(SIMD3<Float>(1, 1, 1))
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XCTAssertEqual(out.x, 0.6, accuracy: 1e-4) // master 1->0.5, red 0.5->0.6
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XCTAssertEqual(out.y, 0.5, accuracy: 1e-4)
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XCTAssertEqual(out.z, 0.5, accuracy: 1e-4)
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}
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func testCurveSetIdentityNoOp() {
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let out = CurveSet.identity.apply(SIMD3<Float>(0.3, 0.6, 0.9))
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XCTAssertEqual(out.x, 0.3, accuracy: 1e-6)
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XCTAssertEqual(out.y, 0.6, accuracy: 1e-6)
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XCTAssertEqual(out.z, 0.9, accuracy: 1e-6)
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}
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}
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