Light Beam Particles

mxt:light_beam is a glowing stream along the world Y axis with a circular cross-section. Solid streaks fill the disk by default; filled:false places them only on the column's surface. Each streak is a closed cylinder with a constant radius, while spread:true gives it a broad middle and tapered ends. Each streak chooses a random transverse position when it is emitted and keeps that position in the vertical section; later streaks choose new positions. Some streaks are thin and sharp; others are wider with a faint, soft halo. Gaps separate the streaks as they flow in the selected direction. It uses the particle system and works with /particle, datapack particle effects, and other particle emitters.

Quick test

This command creates a default pale-yellow, upward-flowing light beam that is eight blocks tall and lasts 40 ticks:

/particle mxt:light_beam{y_max:8.0f} ~ ~ ~ 0 0 0 0 1 force

A blue light beam flowing downward:

/particle mxt:light_beam{color:"#FF79BFFF",y_min:-2.0f,y_max:6.0f,width:0.24f,flow_direction:"down",flow_speed:1.8f,lifetime:200} ~ ~ ~ 0 0 0 0 1 force

Coloured streams

Each column uses one colour. Run these three commands separately to place cyan, golden-yellow, and violet streams nearby for 60 seconds:

/particle mxt:light_beam{color:"#FF22FFFF",y_max:24.0f,width:0.5f,lifetime:1200} ~-3 ~ ~5 0 0 0 0 1 force
/particle mxt:light_beam{color:"#FFFFE91C",y_max:24.0f,width:0.5f,lifetime:1200} ~ ~ ~5 0 0 0 0 1 force
/particle mxt:light_beam{color:"#FF9A21FF",y_max:24.0f,width:0.5f,lifetime:1200} ~3 ~ ~5 0 0 0 0 1 force

These commands use a count of 1, with all spread values and velocity set to 0. One particle draws a complete column; emit separately at each position when you need several columns.

Distribution radius and density

radius controls the radius of the horizontal disk containing the streaks. It defaults to 0.5 blocks and accepts values from 0.001 to 64. width controls the thickness and length scale of individual streaks. density specifies flow channels per square block of cross-section, defaults to 16, and accepts values from 0.001 to 1024. The channel count is ceil(π × radius² × density): below the limits, doubling the radius produces approximately four times as many channels and preserves the distribution density:

/particle mxt:light_beam{color:"#FF22FFFF",radius:1.5f,density:16.0f,width:0.18f,y_max:12.0f,spread:true,lifetime:1200} ~ ~ ~6 0 0 0 0 1 force

Each column uses at most 1024 flow channels and has a draw budget of 2048 entries. Each streak uses one entry; enabling glow uses one additional entry for the whole column's glow. Very large radii, densities or heights produce a sparser distribution once a limit is reached. Channels determine how many streams emit streaks along the height; each streak has its own random transverse position, so they do not form fixed tracks.

The client has a total draw budget of 8192 entries per frame, shared by all columns' streaks and column glows. When the budget is exhausted, nearby columns receive a greater share of the density; if more than 8192 columns are visible, farther columns may be omitted. Cross-sections and bends use fewer subdivisions at distance, with thresholds at 32 and 96 blocks. Streaks retain a solid shape at every distance.

The local halos extend slightly beyond the distribution disk; client culling bounds include them.

Surface distribution and static glow

filled defaults to true, distributing streaks throughout the disk. Setting it to false places streak centres only on the whole column's cylindrical surface, leaving the interior empty. Individual streaks keep their solid shape. Both distributions use the same density count formula.

glow defaults to false. Enabling it adds a static glow of the same colour inside the column. Its extent follows radius, y_min and y_max; its opacity follows color and the whole column's lifetime fade. It has no flow animation and is unaffected by flow_direction, flow_speed or spread. It does not extend onto the terminal planes. This switch does not affect the local halos around individual streaks.

This creates a beam with streaks only on its surface and a static glow inside:

/particle mxt:light_beam{filled:false,glow:true,radius:1.0f,y_max:8.0f,spread:true,lifetime:1200} ~ ~ ~6 0 0 0 0 1 force

Broader streaks

spread defaults to false, which keeps each streak as a closed cylinder with a constant radius. Set it to true to make every streak wider and longer, with wider streaks also receiving more length. Each tapers smoothly from its broad middle to pointed upper and lower ends, while retaining its own brightness, opacity, and soft glow:

/particle mxt:light_beam{color:"#FF22FFFF",y_max:24.0f,width:0.5f,spread:true,lifetime:1200} ~ ~ ~6 0 0 0 0 1 force

In JSON, put the boolean inside the particle object. It controls streak shape; the outer particle effect's spread array controls emission scatter. Both can be used together:

{
  "particle": {
    "type": "mxt:light_beam",
    "y_max": 24.0,
    "radius": 1.5,
    "density": 16.0,
    "width": 0.5,
    "spread": true,
    "filled": false,
    "glow": true,
    "lifetime": 1200
  },
  "count": 1,
  "speed": 0,
  "spread": [0, 0, 0]
}

Flow at the terminal planes

bottom_effect and top_effect independently enable the lower and upper terminal effects. Both default to false. Streaks turn smoothly along a circular arc between the vertical column and a horizontal plane, keeping their solid cross-sections. spread still selects constant-radius or tapered streaks. The planes are at y_min and y_max; they do not inspect blocks or tilt with terrain.

flow_direction	Lower terminal	Upper terminal
"up"	Converge inward along the plane, then flow upward	Turn onto the plane and spread outward
"down"	Turn onto the plane and spread outward	Converge inward along the plane, then flow downward

These two columns flow upward and downward, with both terminals enabled:

/particle mxt:light_beam{color:"#FF22FFFF",y_max:8.0f,radius:0.8f,width:0.18f,spread:true,bottom_effect:true,top_effect:true,lifetime:1200} ~-3 ~ ~6 0 0 0 0 1 force
/particle mxt:light_beam{color:"#FFFF79BF",y_max:8.0f,radius:0.8f,width:0.18f,spread:true,flow_direction:"down",bottom_effect:true,top_effect:true,lifetime:1200} ~3 ~ ~6 0 0 0 0 1 force

For outward flow at the lower terminal only, select downward flow and enable only bottom_effect:

/particle mxt:light_beam{y_max:8.0f,flow_direction:"down",bottom_effect:true,lifetime:1200} ~ ~ ~6 0 0 0 0 1 force

The outward reach is automatically set to max(0.75, radius × 1.5, width × 4) blocks and fades near its outer edge. Streak centres lie on the terminal plane, while their cross-sections and halos extend slightly to either side. Client culling bounds include the full extension and halos. Terminals share the column's draw budget of 2048 entries; enabling them increases mesh cost.

Fields

Field	Default	Meaning
color	#FFFFE8A8	ARGB colour. The highest byte is the overall alpha.
x / z	0 / 0	Horizontal offset from the particle spawn point.
y_min / y_max	0 / 8	Vertical range relative to the particle spawn point; y_max must be greater than y_min.
radius	0.5	Distribution radius of the horizontal disk, from 0.001 to 64 blocks.
density	16	Flow channels per square block of cross-section, from 0.001 to 1024.
width	0.18	Individual streak size; its halo spans at most 1.4 times this value.
spread	false	Keep a closed constant-radius cylinder; true makes streaks wider and longer, with a broad middle and smoothly tapered, pointed ends.
filled	true	Distribute streaks throughout the disk; false places them only on the whole column's surface.
glow	false	Draw a static glow of the same colour inside the column.
bottom_effect	false	Enable inward or outward flow on the lower plane at y_min.
top_effect	false	Enable inward or outward flow on the upper plane at y_max.
flow_direction	"up"	Streak movement direction, either "up" or "down".
flow_speed	1	Streak movement speed; it cannot be negative.
lifetime	40	Particle lifetime in ticks.

color uses an ARGB string, for example #CCFFF0A0 is about 80% opaque. The light beam uses full-bright lighting, so its colour and halo remain visible in shadow.

Set flow_speed:0.0f to pause streak movement. Columns fade in and out at the beginning and end of their lifetime, and each column starts at a slightly different point in the pattern.

Scene depth enhancement

Client configuration “World Effects → Scene depth enhancement” is disabled by default. When enabled, streaks fade softly where they meet opaque terrain, and the column glow is clipped against that terrain. It reads the opaque scene only: it does not provide exact occlusion between glass, water or other transparent effects, and does not add screen-space bloom.

The basic effect is used when the enhancement is unavailable. With shader packs, check occlusion in front of and behind walls, from inside the column, and while moving the camera. Disable this option if the effect becomes misaligned or leaks through surfaces. The particle's glow parameter still determines whether the column glow is drawn.

Visibility of tall columns

The server uses vanilla particle delivery rules, measuring from the centre of the player's block to the particle spawn point: 32 blocks in normal mode or 512 blocks with force. radius, x / z, the vertical range and terminal extensions do not expand this range. A nearby section of a column is not enough to receive the particle if its spawn point is too far away.

Once received, the client checks the full column against the view. A visible middle or upper section is enough to draw it; the spawn point does not need to be on screen. Terrain occlusion and distance fog still apply. Its emissive appearance does not illuminate nearby blocks.