Godot 4.x Compute Example

test.gd

extends Node
# Based on this tweet by Clay John:
# https://twitter.com/john_clayjohn/status/1306447928932753408


func _ready() -> void:
	
	# Create a local rendering device.
	var rd := RenderingServer.create_local_rendering_device()
	
	# Load GLSL shader
	var shader_file := load("res://test.glsl")
	var shader_spirv: RDShaderSPIRV = shader_file.get_spirv()
	var shader := rd.shader_create_from_spirv(shader_spirv)
	
	# Prepare our data. We use doubles in the shader, so we need 64 bit.
	var input := PackedFloat64Array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
	var input_bytes := input.to_byte_array()
	
	# Create a storage buffer that can hold 10 double values. Each
	# double has 8 byte (64 bit) so 10 x 8 = 80 bytes
	var buffer := rd.storage_buffer_create(80, input_bytes)
	var uniform := RDUniform.new()
	uniform.uniform_type = RenderingDevice.UNIFORM_TYPE_STORAGE_BUFFER
	uniform.binding = 0
	uniform.add_id(buffer)
	var uniform_set := rd.uniform_set_create([uniform], shader, 0)
	
	# Create a compute pipeline
	var pipeline := rd.compute_pipeline_create(shader)
	var compute_list := rd.compute_list_begin()
	rd.compute_list_bind_compute_pipeline(compute_list, pipeline)
	rd.compute_list_bind_uniform_set(compute_list, uniform_set, 0)
	rd.compute_list_dispatch(compute_list, 5, 1, 1)
	rd.compute_list_end()
	
	# Submit to GPU and wait for sync
	rd.submit()
	rd.sync()
	
	# Read back the data from the buffers
	var output_bytes := rd.buffer_get_data(buffer)
	var output := output_bytes.to_float64_array()
	print(output)
 

test.glsl

#[compute]

#version 450

// Based on this tweet by Clay John:
// https://twitter.com/john_clayjohn/status/1306447928932753408

layout(local_size_x = 4) in;

layout(set = 0, binding = 0, std430) restrict buffer MyBuffer {
  double data[];
}
my_buffer;

void main() {
    // gl_GlobalInvocationID.x uniquely identifies this invocation within the work group
    my_buffer.data[gl_GlobalInvocationID.x] *= 2.0;
}