Adding upstream version 0.0~git20250520.a1d9079+dfsg.

Signed-off-by: Daniel Baumann <daniel@debian.org>

exp/sprite/clock/tween_test.go

@@ -0,0 +1,53 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package clock
+
+import "testing"
+
+func TestLinear(t *testing.T) {
+	t0 := Time(0)
+	t1 := Time(6 * 60)
+	now := Time(3 * 60)
+
+	if c := Linear(t0, t1, now); c != 0.5 {
+		t.Errorf("c=%.2f, want 0.5", c)
+	}
+}
+
+func TestCubicBezier(t *testing.T) {
+	t0 := Time(0)
+	t1 := Time(1e6)
+
+	tests := []struct {
+		x0, y0, x1, y1 float32
+		x, y           float32
+	}{
+		{0.00, 0.1, 0.4, 1.00, 0.0, 0.00},
+		{0.00, 0.1, 0.4, 1.00, 0.1, 0.26},
+		{0.00, 0.1, 0.4, 1.00, 0.5, 0.79},
+		{0.00, 0.1, 0.4, 1.00, 0.9, 0.99},
+		{0.00, 0.1, 0.4, 1.00, 1.0, 1.00},
+		{0.36, 0.2, 0.3, 0.85, 0.0, 0.0},
+		{0.36, 0.2, 0.3, 0.85, 0.3059, 0.3952},
+		{0.36, 0.2, 0.3, 0.85, 0.4493, 0.6408},
+		{0.36, 0.2, 0.3, 0.85, 0.8116, 0.9410},
+		{0.00, 0.0, 1.0, 1.00, 0.1, 0.1},
+		{0.00, 0.0, 1.0, 1.00, 0.5, 0.5},
+		{0.00, 0.0, 1.0, 1.00, 0.9, 0.9},
+		{0.42, 0.0, 1.0, 1.00, 0.0, 0.0},
+	}
+
+	for _, test := range tests {
+		cb := CubicBezier(test.x0, test.y0, test.x1, test.y1)
+		now := t0 + Time(float32(t1-t0)*test.x)
+		y := cb(t0, t1, now)
+
+		const epsilon = 0.01
+		diff := y - test.y
+		if diff < -epsilon || +epsilon < diff {
+			t.Errorf("CubicBezier(%.2f,%.2f,%.2f,%.2f): for x=%.2f got y=%.2f, want %.2f", test.x0, test.y0, test.x1, test.y1, test.x, y, test.y)
+		}
+	}
+}