How to turn of the light casting shadow

[HSDSZ]

Like the function in eevee, If i turn the swtich off, the shadow disappear. Any way to achieve this function in malt light settingn?

[pragma37]

While I think we should add this as a built-in feature, you can get the same result using Light Groups.
If you set the Sun Light Group to 2, for example, you can set your Materials Light Groups like this:

So this Material receives light from Light Group 2 but doesn't cast shadows in it.
Lights in Light Group 1 will still work as normal.

[HSDSZ]

I am also doing this as a work around. But I have a lot of assets, it is hard to go back and give every material an extra light number.

I am wondering is it possible to let all material always use an internal light group and shadow group number, such as -999.

If i want a light to turn off casting shadow, I just add a new light, set the light group to -999, shadow group to other, then it will work.

[pragma37]

You can run a script that sets the Light Group for you.
So, if your "no shadows" group is -1 you can run this script from the Blender Text Editor:

import bpy
for material in bpy.data.materials:
    if "Light Groups.Light" in material.malt_parameters.keys():
        material.malt_parameters["Light Groups.Light"][3] = -1

If you check the Register option it will run automatically when you load the file.

[HSDSZ]

This script does not work for linked material. Although it changes the linked light group socket.

[HSDSZ]

Just got a way.

I changed the pipeline.py. ^_^
set the default light group to -99 and shadow group to -98. Then I could have light that only cast shadow or only light up