GeometryData Geometry::createCylinderGeometry(unsigned int segments, float height, float radius)
{
	GeometryData data;

	// center vertices
	data.positions.push_back(glm::vec3(0, -height / 2.0f, 0));
	data.normals.push_back(glm::vec3(0.0f, -1, 0.0f));

	data.positions.push_back(glm::vec3(0, height / 2.0f, 0));
	data.normals.push_back(glm::vec3(0.0f, 1, 0.0f));

	// circle top and bottom
	float angle_step = 2.0f * glm::pi<float>() / float(segments);
	//side faces
	for (unsigned int i = 0; i < segments; i++) {
		glm::vec3 circlePos = glm::vec3(
			glm::cos(i * angle_step) * radius,
			-height / 2.0f,
			glm::sin(i * angle_step) * radius
		);
		// bottom ring vertex
		data.positions.push_back(circlePos);

		// top ring vertex
		circlePos.y = height / 2.0f;
		data.positions.push_back(circlePos);

		//needs to be calculated from the circle -> y = 0
		circlePos.y = 0;
		data.normals.push_back(glm::normalize(circlePos));
		data.normals.push_back(glm::normalize(circlePos));

		data.indices.push_back(2 + i * 2);
		data.indices.push_back(i == segments - 1 ? 3 : 3 + (i + 1) * 2);
		data.indices.push_back(i == segments - 1 ? 2 : 2 + (i + 1) * 2);

		data.indices.push_back(i == segments - 1 ? 3 : 3 + (i + 1) * 2);
		data.indices.push_back(2 + i * 2);
		data.indices.push_back(3 + i * 2);

	}

	for (unsigned int i = 0; i < segments; i++) {
		glm::vec3 circlePos = glm::vec3(
			glm::cos(i * angle_step) * radius,
			-height / 2.0f,
			glm::sin(i * angle_step) * radius
		);

		// bottom ring vertex
		data.positions.push_back(circlePos);
		data.normals.push_back(glm::vec3(0.0f, -1, 0.0f));

		// top ring vertex
		circlePos.y = height / 2.0f;
		data.positions.push_back(circlePos);
		data.normals.push_back(glm::vec3(0.0f, 1, 0.0f));

		int offset = segments*2;
		// bottom face
		data.indices.push_back(0);
		data.indices.push_back(2+ offset + i * 2);
		data.indices.push_back(i == segments - 1 ? 2+ offset : 2+ offset + (i + 1) * 2);

		// top face
		data.indices.push_back(1);
		data.indices.push_back(i == segments - 1 ? 3+ offset : 3+ offset + (i + 1) * 2);
		data.indices.push_back(3+ offset + i * 2);
	}

	return std::move(data);
}