CylinderMesh constructor

Implementation

CylinderMesh({
  required double radius,
  required double height,
  int segments = 16,
  Material? material,
}) {
  final vertices = <Vertex>[];
  final halfHeight = height / 2.0;

  // top circle
  for (var i = 0; i <= segments; i++) {
    final theta = i * tau / segments;
    final x = radius * math.cos(theta);
    final y = halfHeight;
    final z = radius * math.sin(theta);

    final u = (1 + math.cos(theta)) * 0.5;
    final v = (1 + math.sin(theta)) * 0.5;

    vertices.add(
      Vertex(position: Vector3(x, y, z), texCoord: Vector2(u, v)),
    );
  }

  // top center
  vertices.add(
    Vertex(position: Vector3(0, halfHeight, 0), texCoord: Vector2(0.5, 0.5)),
  );

  // bottom circle
  for (var i = 0; i <= segments; i++) {
    final theta = i * tau / segments;
    final x = radius * math.cos(theta);
    final y = -halfHeight;
    final z = radius * math.sin(theta);

    final u = (1 + math.cos(theta)) * 0.5;
    final v = (1 + math.sin(theta)) * 0.5;

    vertices.add(
      Vertex(position: Vector3(x, y, z), texCoord: Vector2(u, v)),
    );
  }

  // bottom center
  vertices.add(
    Vertex(position: Vector3(0, -halfHeight, 0), texCoord: Vector2(0.5, 0.5)),
  );

  final indices = <int>[];

  // top circle indices
  for (var i = 0; i < segments; i++) {
    indices.add(i);
    indices.add(i + 1);
    indices.add(segments + 1); // center index
  }

  // bottom circle indices
  for (var i = 0; i < segments; i++) {
    indices.add(segments + 1 + i);
    indices.add(segments + 1 + i + 1);
    indices.add(segments * 2 + 2); // center index
  }

  // side indices
  for (var i = 0; i < segments; i++) {
    final topIndex = i;
    final bottomIndex = i + segments + 1;
    indices.add(topIndex);
    indices.add(bottomIndex);
    indices.add(topIndex + 1);

    indices.add(bottomIndex);
    indices.add(bottomIndex + 1);
    indices.add(topIndex + 1);
  }

  addSurface(
    Surface(
      vertices: vertices,
      indices: indices,
      material: material,
    ),
  );
}