blender/doc/python_api/examples/gpu.10.py

"""
Rendering the 3D View into a Texture
------------------------------------

The scene has to have a camera for this example to work.
You could also make this independent of a specific camera,
but Blender does not expose good functions to create view and projection matrices yet.
"""
import bpy
import bgl
import gpu
from gpu_extras.presets import draw_texture_2d

WIDTH = 512
HEIGHT = 256

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


def draw():
    context = bpy.context
    scene = context.scene

    view_matrix = scene.camera.matrix_world.inverted()

    projection_matrix = scene.camera.calc_matrix_camera(
        context.evaluated_depsgraph_get(), x=WIDTH, y=HEIGHT)

    offscreen.draw_view3d(
        scene,
        context.view_layer,
        context.space_data,
        context.region,
        view_matrix,
        projection_matrix)

    bgl.glDisable(bgl.GL_DEPTH_TEST)
    draw_texture_2d(offscreen.color_texture, (10, 10), WIDTH, HEIGHT)


bpy.types.SpaceView3D.draw_handler_add(draw, (), 'WINDOW', 'POST_PIXEL')