Overlapping opaque black polygons with white edges

[superfede76]

Hi all,
I need to overlap some triangles so that you can only see the white edge, and inside it is black. If I try to fill the interior with another color,fro example blue, it works, but with black it does not.

this is my code working with blu tringles with white boundary

import ezdxf
import random

def create_solid_triangles_inside_square(num_triangles):
    doc = ezdxf.new(dxfversion="R2010")
    msp = doc.modelspace()
    for _ in range(num_triangles):
        triangle_vertices = [
            (random.uniform(0, 10), random.uniform(0, 10)),
            (random.uniform(0, 10), random.uniform(0, 10)),
            (random.uniform(0, 10), random.uniform(0, 10))
        ]
        msp.add_solid(triangle_vertices, dxfattribs={'color': 1})
        msp.add_lwpolyline(triangle_vertices, close=True, dxfattribs={'color': 7})
    doc.saveas("marker.dxf")

if __name__ == "__main__":
    num_triangles = 5
    create_solid_triangles_inside_square(num_triangles)

Can anyone help?
Thank you

Edit: I need to overlap some triangles so that you can only see the white edge, and inside it is empty (not black!) like in the below example.

[mozman]

You cannot use ACI as color for that specific use case. ACI stands for AutoCAD Color Index and is simply an index into a vendor specific color table or a color table that you provide as a .ctb file. The index 7 is very special because it is white on a dark background and black on a light background. You could use ACI 250 for black and 255 for white:

DWG Trueview Modelspace:

DWG Trueview Paperspace:

But BricsCAD disagree about these default colors:

The better way is to use true color values:

import ezdxf
from ezdxf import colors
import random


def create_solid_triangles_inside_square(num_triangles):
    doc = ezdxf.new(dxfversion="R2010")
    msp = doc.modelspace()
    for _ in range(num_triangles):
        triangle_vertices = [
            (random.uniform(0, 10), random.uniform(0, 10)),
            (random.uniform(0, 10), random.uniform(0, 10)),
            (random.uniform(0, 10), random.uniform(0, 10)),
        ]
        msp.add_solid(
            triangle_vertices, dxfattribs={"true_color": colors.rgb2int((0, 0, 0))}
        )
        msp.add_lwpolyline(
            triangle_vertices,
            close=True,
            dxfattribs={"true_color": colors.rgb2int((255, 255, 255))},
        )
    doc.saveas("marker_rgb.dxf")


if __name__ == "__main__":
    num_triangles = 5
    create_solid_triangles_inside_square(num_triangles)

That guarantees to get the same color in every CAD application (if you ignore color spaces):

[superfede76]

Hi Mozamn, thanks for the reply. I realized that I am explained badly. What I want to do is erase everything that's inside the triangle and don't color it in black. Here an example:
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