Exporting STEP with colors doesn't de-duplicate as expected with different, but same-valued Colors

[johnbeard]

When adding to an Assembly, it seems that the color/object tuples aren't correctly de-duplicating:

        # define the current color
        current_color = el.color if el.color else color

        # add a leaf with the actual part if needed
        if el.obj:
            # get/register unique parts referenced in the assy
            key0 = (current_color, el.obj)  # (color, shape)  # <<------- a different object (not value) here
            key1 = el.obj  # shape

            if key0 in unique_objs:   # <---- fails this check
                lab = unique_objs[key0]
            else:
                lab = tool.NewShape()
                if key1 in compounds:

If you add items to the assembly using a single Color, it's works like you expect:

def single_color_object():
    # Create an assembly
    assembly = cq.Assembly()
    color = cq.Color(0, 0, 1) # <---- same!

    # Add 4 cubes in a 2x2 grid
    for i in range(2):
        for j in range(2):
            assembly.add(
                cube,
                loc=cq.Location(
                    cq.Vector(i * 2, j * 2, 0),
                ),
                # Same object each time
                color=color,
            )

    return assembly

This returns 4 cubes all the same object (exports to ~25kB)

If you make a new color each time with the same value, you get duplicated cubes:

def multi_same_color_object():
    # Create an assembly
    assembly = cq.Assembly()

    # Add 4 cubes in a 2x2 grid
    for i in range(2):
        for j in range(2):
            assembly.add(
                cube,
                loc=cq.Location(
                    cq.Vector(i * 2, j * 2, 0),
                ),
                # This is always the same value, but it's a different object
                color=cq.Color(0, 0, 1),
            )

    return assembly

This returns 4 same coloured cubes, but they're all "new" objects (exports to ~75kB)

In fact, you can even subvert it the other way by changing the value, not the object:

def multi_different_color_object():
    # Create an assembly
    assembly = cq.Assembly()
    color = cq.Color(0, 0, 1)

    # Add 4 cubes in a 2x2 grid
    for i in range(2):
        for j in range(2):
            # Change the color "secretly"
            color.r = i / 2
            color.g = j / 2
            color.b = 0
            assembly.add(
                cube,
                loc=cq.Location(
                    cq.Vector(i * 2, j * 2, 0),
                ),
                # Same object each time
                # but the value changed
                color=color,
            )

    return assembly

Saving this makes 4 identically coloured cubes (exports to ~25kB)

It seems to me that this should be a by-value comparison rather than checking if it's literally the same object?

Script to replicate:
cq_export_color.zip

Version:

cadquery                      2.4.0
cadquery-ocp                  7.7.2

[lorenzncode]

Yes, agree. I can reproduce it. Thanks for the report and script.