"""
Copy Off-screen Rendering result back to RAM
--------------------------------------------

This will create a new image with the given name.
If it already exists, it will override the existing one.
"""
import bpy
import gpu
import random
from mathutils import Matrix
from gpu_extras.presets import draw_circle_2d

IMAGE_NAME = "Generated Image"
WIDTH = 512
HEIGHT = 512
RING_AMOUNT = 10


offscreen = gpu.types.GPUOffScreen(WIDTH, HEIGHT)

with offscreen.bind():
    fb = gpu.state.active_framebuffer_get()
    fb.clear(color=(0.0, 0.0, 0.0, 0.0))
    with gpu.matrix.push_pop():
        # Reset matrices -> use normalized device coordinates [-1, 1].
        gpu.matrix.load_matrix(Matrix.Identity(4))
        gpu.matrix.load_projection_matrix(Matrix.Identity(4))

        for i in range(RING_AMOUNT):
            draw_circle_2d(
                (random.uniform(-1, 1), random.uniform(-1, 1)),
                (1, 1, 1, 1), random.uniform(0.1, 1),
                segments=20,
            )

    buffer = fb.read_color(0, 0, WIDTH, HEIGHT, 4, 0, 'FLOAT')

offscreen.free()


if IMAGE_NAME not in bpy.data.images:
    bpy.data.images.new(IMAGE_NAME, WIDTH, HEIGHT)
image = bpy.data.images[IMAGE_NAME]
image.scale(WIDTH, HEIGHT)

buffer.dimensions = WIDTH * HEIGHT * 4
image.pixels[:] = buffer