bedrock-samples/resource_pack/particles/mob_portal.json

{
  "format_version": "1.10.0",
  "particle_effect": {
    "description": {
      "identifier": "minecraft:mob_portal",
      "basic_render_parameters": {
        "material": "particles_alpha",
        "texture": "textures/particle/particles"
      }
    },
    "components": {
      "minecraft:emitter_rate_manual": {
        "max_particles": 1000
      },

      "minecraft:emitter_lifetime_expression": {
        "activation_expression": 1,
        "expiration_expression": 0
      },

      "minecraft:emitter_shape_point": {
        "direction": [0, -1, 0]
      },

      "minecraft:particle_lifetime_expression": {
        "max_lifetime": "Math.Random(2.0,2.45)"
      },

      "minecraft:particle_initial_speed": "1",

      "minecraft:particle_motion_dynamic": {
        "linear_acceleration": ["variable.xaccel", 0.55, "variable.zaccel"]
      },

      "minecraft:particle_initialization": {
        "per_update_expression": "variable.xaccel = variable.particle_random_3 - 0.5; variable.zaccel = variable.particle_random_4 - 0.5;",
        "per_render_expression": "variable.size = (variable.particle_random_2 * 0.02 + 0.05) * (1 - Math.Pow((1-(variable.particle_age/variable.particle_lifetime)),2)); variable.color = (variable.particle_random_1 * 0.6 + 0.4);"
      },

      "minecraft:particle_appearance_billboard": {
        "size": ["variable.size", "variable.size"],
        "facing_camera_mode": "lookat_xyz",

        "uv": {
          "texture_width": 128,
          "texture_height": 128,
          "uv": [ "Math.round(variable.particle_random_3*8)*8", 0 ],
          "uv_size": [ 8, 8 ]
        }
      },
      "minecraft:particle_appearance_tinting": {
        "color": [ "variable.color", "variable.color * 0.3", "variable.color * 0.9", 1.0 ]
      }
    }
  }
}