A CylinderGeometry with 24 radial segments has 148 vertices and 96 indices, but that could be optimized to 49 vertices (24 for base + 1 NaN + 24 for top) and 92 indices (22 for base + 22 for top + 2 times 24 for body).
My problem is that I don’t know how to calculate the vertex normals for my “cylinder algorithm”.
geometry.calculateVertexNormals() doesn’t works. The result of this is:
My code:
const cylinderGeometry = new BufferGeometry()
.setAttribute(
'position',
new BufferAttribute(new Float32Array([
// cylinder base
0, -1, 0,
0.2588, -0.9659, 0,
0.5, -0.866, 0,
0.7071, -0.7071, 0,
0.866, -0.5, 0,
0.9659, -0.2588, 0,
1, 0, 0,
0.9659, 0.2588, 0,
0.866, 0.5, 0,
0.7071, 0.7071, 0,
0.5, 0.866, 0,
0.2588, 0.9659, 0,
0, 1, 0,
-0.2588, 0.9659, 0,
-0.5, 0.866, 0,
-0.7071, 0.7071, 0,
-0.866, 0.5, 0,
-0.9659, 0.2588, 0,
-1, 0, 0,
-0.9659, -0.2588, 0,
-0.866, -0.5, 0,
-0.7071, -0.7071, 0,
-0.5, -0.866, 0,
-0.2588, -0.9659, 0,
0, -1, 0,
// This position attribute is also used in the edges.
// The edges are drawn with Line instead of LineSegments for better
// performance, but lines, differently from line segements are continuous,
// except if we add NaNs between the lines.
// HACK:
NaN, NaN, NaN,
// cylinder top
0, -1, -1,
0.2588, -0.9659, -1,
0.5, -0.866, -1,
0.7071, -0.7071, -1,
0.866, -0.5, -1,
0.9659, -0.2588, -1,
1, 0, -1,
0.9659, 0.2588, -1,
0.866, 0.5, -1,
0.7071, 0.7071, -1,
0.5, 0.866, -1,
0.2588, 0.9659, -1,
0, 1, -1,
-0.2588, 0.9659, -1,
-0.5, 0.866, -1,
-0.7071, 0.7071, -1,
-0.866, 0.5, -1,
-0.9659, 0.2588, -1,
-1, 0, -1,
-0.9659, -0.2588, -1,
-0.866, -0.5, -1,
-0.7071, -0.7071, -1,
-0.5, -0.866, -1,
-0.2588, -0.9659, -1,
0, -1, -1
]), 3)
)
.setIndex([
// cylinder base
1, 2, 3,
3, 4, 5,
3, 5, 7,
5, 6, 7,
7, 8, 9,
7, 9, 11,
7, 11, 15,
9, 10, 11,
11, 12, 13,
11, 13, 15,
13, 14, 15,
15, 16, 17,
15, 17, 19,
15, 19, 23,
17, 18, 19,
19, 20, 21,
19, 21, 23,
21, 22, 23,
23, 0, 1,
23, 1, 3,
23, 3, 7,
23, 7, 15,
// cylinder top
28, 27, 26,
30, 29, 28,
32, 30, 28,
32, 31, 30,
34, 33, 32,
36, 34, 32,
40, 36, 32,
36, 35, 34,
38, 37, 36,
40, 38, 36,
40, 39, 38,
42, 41, 40,
44, 42, 40,
48, 44, 40,
44, 43, 42,
46, 45, 44,
48, 46, 44,
48, 47, 46,
26, 25, 48,
28, 26, 48,
32, 28, 48,
40, 32, 48,
// cylinder body
26, 1, 0,
26, 27, 1,
27, 2, 1,
27, 28, 2,
28, 3, 2,
28, 29, 3,
29, 4, 3,
29, 30, 4,
30, 5, 4,
30, 31, 5,
31, 6, 5,
31, 32, 6,
32, 7, 6,
32, 33, 7,
33, 8, 7,
33, 34, 8,
34, 9, 8,
34, 35, 9,
35, 10, 9,
35, 36, 10,
36, 11, 10,
36, 37, 11,
37, 12, 11,
37, 38, 12,
38, 13, 12,
38, 39, 13,
39, 14, 13,
39, 40, 14,
40, 15, 14,
40, 41, 15,
41, 16, 15,
41, 42, 16,
42, 17, 16,
42, 43, 17,
43, 18, 17,
43, 44, 18,
44, 19, 18,
44, 45, 19,
45, 20, 19,
45, 46, 20,
46, 21, 20,
46, 47, 21,
47, 22, 21,
47, 48, 22,
48, 23, 22,
48, 49, 23,
49, 24, 23,
49, 50, 24,
]);
