Lua實現angle角__angle角

function i3k_vec3(x, y, z)return { x = x, y = y, z = z };endfunction i3k_vec3_normalize1(v)return i3k_vec3_normalize2(v.x, v.y, v.z);endfunction i3k_vec3_normalize2(x, y, z)local _x = x;local _y = y;local _z = z;local d = math.sqrt(_x * _x + _y * _y + _z * _z);if d ~= 0 then_x = _x / d;_y = _y / d;_z = _z / d;endreturn i3k_vec3(_x, _y, _z);end-- only x, zfunction i3k_vec3_angle1(p1, p2, p3)return i3k_vec3_angle2(i3k_vec3(p1.x - p2.x, 0, p1.z - p2.z), p3);endfunction i3k_vec3_angle2(p1, p2)local _v1 = i3k_vec3_normalize1(p1);local _v2 = i3k_vec3_normalize1(p2);local epsilon = 0.000001;local dot = _v1.x * _v2.x + _v1.z * _v2.z;local angle = 0;if math.abs(dot - 1) <= epsilon thenangle = 0;elseif math.abs(dot + 1) <= epsilon thenangle = math.pi;elseangle = math.acos(dot);local cross = _v1.x * _v2.z - _v2.x * _v1.z;if cross < 0 thenangle = 2 * math.pi - angle;endendreturn angle;end