Shaderboard

Shaderboard

Shaderboard lets vanilla resource-pack post-effect shaders read client-side scoreboard values through named bindings.

A binding is declared inside a post-effect's JSON file (the same file that defines its passes). This mod turns each binding into a real GLSL uniform block with a GPU buffer, and rewrites those buffers with live scoreboard values every frame. Shaders can then use those values however they like.

> Note: This mod is for vanilla /posteffect command shaders. It does not target shaders from mods like Iris and Optifine.

> IMPORTANT: Scoreboard scores are server-sided and by default do not synchronize with clients. Use /scoreboard objectives setdisplay ... to get an objective's scores to synchronize with clients, so post-effect shaders can read them.

Declaring bindings

Add a "shaderboard:bindings" array at the root of a post-effect JSON, next to "targets" and "passes". Here is an example:

{
	"targets": { ... },
	"passes": [ ... ],

	"shaderboard:bindings":
	[
		{
			"uniform_name": "u_TopScore",
			"type": "shaderboard:scoreboard_objective",
			"objective": "example_1",
			"target": { "type": "top_player" }
		},
		{
			"uniform_name": "u_MyScore",
			"type": "shaderboard:scoreboard_objective",
			"objective": "example_1",
			"target": { "type": "local_player" }
		},
		{
			"uniform_name": "u_SteveScore",
			"type": "shaderboard:scoreboard_objective",
			"objective": "example_1",
			"target": { "type": "player", "name": "Steve" }
		},
		{
			"uniform_name": "u_SortedScoresAZ",
			"type": "shaderboard:scoreboard_objective",
			"objective": "example_1",
			"target":
			{
				"type": "array",
				"count": 16,
				"include_hidden": true,
				"sort": [
					{ "by": "name", "order": "ascending" }
				],
				"offset": 0
			}
		}
	]
}

Where:

• uniform_name - Name of the GLSL uniform block a binding creates.
• type - Binding type. I.e. the type of information a binding exposes.

When type is shaderboard:scoreboard_objective:

• objective - Scoreboard objective name.
• target - Defines which score of an objective to bind.
  • type - The type of target to bind to; local player's score (local_player), a specific player's score (player), the top score (top_player), or a fixed-size array of scores (array).
  • name - When type is player, this additional field defines "which player".
  • include_hidden - When type is top_player or array; Whether to include hidden scores (whose names start with #). Defaults to false.
  • count - Required for array: fixed array length, from 1 to 128.
  • sort - When type is array; optional array of sort keys. Each entry requires by (name or value) and order (ascending or descending).
  • offset - When type is top_player or array; number of sorted scores to skip. Defaults to 0.

Reading a binding's value in GLSL

Each binding's uniform_name becomes a layout(std140) uniform block. Its contents are defined by the binding's value type. Scalar scoreboard targets produce a single int:

layout(std140) uniform u_TopScore { int topScore; };
layout(std140) uniform u_SortedScoresAZ { int sortedScores[16]; };

void main()
{
	//base output color
	fragColor = texture(InSampler, texCoord);

	//...use 'topScore' and 'sortedScores' however you'd like here...
}

Quick demo

This mod includes an example /posteffect of ID shaderboard:example_1. You may try it out using the following commands in order:

/posteffect add @p shaderboard:example_1

/scoreboard objectives add example_1 dummy "Example 1"
/scoreboard objectives setdisplay sidebar example_1

/scoreboard players set @p example_1 123
/scoreboard players set Steve example_1 456

This example shader reads scoreboard values from the example_1 objective and renders them on-screen as binary stripes.