Fix add entity velocity encoding

internal/protocol/lpvec3_test.go

@@ -0,0 +1,48 @@
+package protocol
+
+import (
+	"bytes"
+	"math"
+	"testing"
+)
+
+func TestLPVec3VanillaFixtures(t *testing.T) {
+	tests := []struct {
+		name      string
+		x, y, z   float64
+		encoded   []byte
+		tolerance float64
+	}{
+		{name: "zero", encoded: []byte{0x00}},
+		{
+			name: "entity velocity", x: 123.0 / 8000.0, y: -456.0 / 8000.0, z: 789.0 / 8000.0,
+			encoded: []byte{0xd9, 0x07, 0x8c, 0x9e, 0xf1, 0x66}, tolerance: 1.0 / 16383.0,
+		},
+		{
+			name: "continuation scale", x: 4.095875,
+			encoded: []byte{0x65, 0xa3, 0x7f, 0xfe, 0xff, 0xff, 0x01}, tolerance: 5.0 / 16383.0,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			w := NewWriter(len(tc.encoded))
+			w.LPVec3(tc.x, tc.y, tc.z)
+			if !bytes.Equal(w.Bytes(), tc.encoded) {
+				t.Fatalf("encoded = % x, want % x", w.Bytes(), tc.encoded)
+			}
+
+			r := NewReader(tc.encoded)
+			x, y, z, err := r.LPVec3()
+			if err != nil {
+				t.Fatal(err)
+			}
+			if math.Abs(x-tc.x) > tc.tolerance || math.Abs(y-tc.y) > tc.tolerance || math.Abs(z-tc.z) > tc.tolerance {
+				t.Fatalf("decoded = (%v, %v, %v), want (%v, %v, %v)", x, y, z, tc.x, tc.y, tc.z)
+			}
+			if r.Remaining() != 0 {
+				t.Fatalf("remaining bytes = %d, want 0", r.Remaining())
+			}
+		})
+	}
+}