How to modify the color of an Omnisurface material using Replicator

[Big_Watermelon]

I would like to use Replicator to modify the color of the OmniSurface material. Specifically, each mesh in my scene has hundreds of different colors, and I need to use Replicator to continuously switch the material colors and render an image for each color.

However, I’ve encountered a problem: I’m using the OmniSurface material because it has the transmission property I need, and the entire simulation is built upon it, so I can’t switch to OmniPBR. When checking the Replicator API, I only found functions that support OmniPBR.

I’m wondering if these APIs can also be applied to OmniSurface, or if there’s another way to modify the color of OmniSurface materials?

[Big_Watermelon]

I’ve discovered that modifying the omnisurface material can be achieved using the following code, provided you first create a list of all materials with different colors.

def get_shapes():

        shapes = rep.get.prims(semantics=[('class', 'cube'), ('class', 'sphere')])

        with shapes:

            rep.modify.material(material_paths)

        return shapes.node

However, there’s currently an issue: modify.material cannot render and output according to the material list’s sequence via distribution.sequence. Is there a way to resolve this?

[Big_Watermelon]

Supplement:

1. rep.get.material did not retrieve the omnisurface material.
2. randomizer.color is not applicable; it defaults to assigning a PBR material.
3. rep.create.from_usd is not applicable; my scene file is very large.

[Big_Watermelon]

I’ve resolved it—rep.modify.material(rep.distribution.sequence(material_paths)) accepts material paths, which I hadn’t noticed before. The code is as follows.

import omni.replicator.core as rep
import omni.kit.commands
import omni.kit.material.library
import asyncio
from pxr import Usd, Gf, Sdf


# 设定反射率参数else
async def on_created(shader_prim: Usd.Prim, ref, tran):
    # 漫反射权重
    shader_prim.CreateAttribute('inputs:diffuse_reflection_weight', Sdf.ValueTypeNames.Float).Set(1)
    # 漫反射反射率
    shader_prim.CreateAttribute('inputs:diffuse_reflection_color', Sdf.ValueTypeNames.Color3f).Set(Gf.Vec3f(ref, 0.0, 0.0))
    # 镜面反射权重
    shader_prim.CreateAttribute('inputs:specular_reflection_weight', Sdf.ValueTypeNames.Float).Set(0.0)


# 创建闭包函数来捕获参数
def create_callback_leaf(ref, tran):
    def callback(prim):
        return asyncio.ensure_future(on_created(prim, ref, tran))
    return callback


with rep.new_layer():

    # Add Default Light
    distance_light = rep.create.light(rotation=(315, 0, 0), intensity=3000, light_type="distant")

    sphere = rep.create.sphere(semantics=[('class', 'sphere')], position=(0, 1, 1))
    cube = rep.create.cube(semantics=[('class', 'cube')],  position=(2, 2, 1))
    plane = rep.create.plane(scale=10, visible=True)

    # 设定反射率参数leaf
    material_paths = []
    # 开始创建材质
    for i in range(50):
        prim_name = 'OmniSurface' + str(i)
        ref = (i+1)/50
        tran = 0
        material_paths.append('/World/Looks/OmniSurface'+str(i))
        omni.kit.commands.execute('CreateAndBindMdlMaterialFromLibrary',
                                    mdl_name='OmniSurface.mdl',
                                    mtl_name='OmniSurface',
                                    prim_name=prim_name,
                                    on_created_fn=create_callback_leaf(ref, tran))

    def get_shapes_new():
        shapes = rep.get.prims(semantics=[('class', 'cube'), ('class', 'sphere')])
        with shapes:
            rep.modify.material(rep.distribution.sequence(material_paths))
        return shapes.node

    rep.randomizer.register(get_shapes_new)

    # Setup randomization
    with rep.trigger.on_frame(num_frames=50):
        rep.randomizer.get_shapes_new()
rep.orchestrator.run()

[Simplychenable]

thanks for reporting back with a solution snippet! i found it very useful.