UI: add optional backdrop to the modal operator overlay to improve readability

[Weisl]

[Weisl]

I don't manage to draw a box in the viewport

[Weisl]

ChatGPT code to draw a rectangle

import bpy
import gpu
from gpu_extras.batch import batch_for_shader

vertices = (
    (100, 100), (300, 100),
    (100, 200), (300, 200))

indices = (
    (0, 1, 2), (2, 1, 3))

shader = gpu.shader.from_builtin('2D_UNIFORM_COLOR')
batch = batch_for_shader(shader, 'TRIS', {"pos": vertices}, indices=indices)


def draw_callback_2d(self, context):
    shader.bind()
    shader.uniform_float("color", (0, 0.5, 0.5, 1.0))
    batch.draw(shader)


class DrawOperator(bpy.types.Operator):
    bl_idname = "object.draw_operator"
    bl_label = "Draw Operator"

    def modal(self, context, event):
        if event.type == 'ESC':
            bpy.types.SpaceView3D.draw_handler_remove(self._handle_2d, 'WINDOW')
            return {'CANCELLED'}

        return {'PASS_THROUGH'}

    def invoke(self, context, event):
        if context.area.type == 'VIEW_3D':
            self._handle_2d = bpy.types.SpaceView3D.draw_handler_add(draw_callback_2d, (self, context), 'WINDOW', 'POST_PIXEL')

            context.window_manager.modal_handler_add(self)
            return {'RUNNING_MODAL'}
        else:
            self.report({'WARNING'}, "View3D not found, cannot run operator")
            return {'CANCELLED'}


def register():
    bpy.utils.register_class(DrawOperator)


def unregister():
    bpy.utils.unregister_class(DrawOperator)


if __name__ == "__main__":
    register()