[BUG] Colors not showing in Isaacsim

[JonathanKuelz]

Bug Description

Rigid bodies made from meshes all appear grey when written to USD in warp and loaded in Isaacsim.

Reason: USD seems to expect one color per vertex, warp gives one color per mesh.

Solution: Changing this line to

mesh.GetDisplayColorAttr().Set(colors * (len(indices) // 3), self.time)

fixes the issue for me. Probably, similar adaptions for primitives with multiple vertices would also be necessary.

Screenshots show before and after in Isaacsim.

Edit: The hotfix is problematic bc. for large meshes, creating a list with duplicated colors like that will cause high memory consumption.

[christophercrouzet]

Hi @JonathanKuelz,

Commit 15d1842 should address this issue and stores the colour using a constant interpolation to avoid taking up more memory than necessary.

Here's a repro I've used that should be similar to your use case and that showcases using both constant and per-vertex colours:

import numpy as np
import pyglet
import warp as wp
import warp.render


BOX_POINTS = np.array(
    (
        ( 0.853553, -0.146446,  0.0     ), ( 0.146446, -0.853553,  0.0     ),
        ( 0.353553,  0.353553,  0.707106), (-0.353553, -0.353553,  0.707106),
        (-0.353553, -0.353553, -0.707106), ( 0.353553,  0.353553, -0.707106),
        (-0.853553,  0.146446,  0.0     ), (-0.146446,  0.853553,  0.0     ),
    ),
    dtype=np.float32,
)

BOX_FACE_VERTEX_INDICES = np.array(
    (
        0, 3, 1, 0, 2, 3, 4, 7, 5, 4, 6, 7, 6, 2, 7, 6, 3, 2,
        5, 1, 4, 5, 0, 1, 5, 2, 0, 5, 7, 2, 1, 6, 4, 1, 3, 6,
    ),
    dtype=np.int32,
)

SPHERE_POINTS = (
    ( 0.0     ,  0.0     , -0.5     ), ( 0.0     ,  0.28656 , -0.425325),
    ( 0.249999,  0.081230, -0.425325), ( 0.0     ,  0.447213, -0.223606),
    ( 0.249999,  0.344095, -0.262865), ( 0.425325,  0.138196, -0.223606),
    ( 0.154508, -0.212662, -0.425325), ( 0.404508, -0.131432, -0.262865),
    ( 0.262865, -0.361803, -0.223606), (-0.154508, -0.212662, -0.425325),
    ( 0.0     , -0.425325, -0.262865), (-0.262865, -0.361803, -0.223606),
    (-0.249999,  0.081230, -0.425325), (-0.404508, -0.131432, -0.262865),
    (-0.425325,  0.138196, -0.223606), (-0.249999,  0.344095, -0.262865),
    (-0.154508,  0.475528,  0.0     ), (-0.404508,  0.293892,  0.0     ),
    (-0.262865,  0.361803,  0.223606), (-0.5     ,  0.0     ,  0.0     ),
    (-0.404508, -0.293892,  0.0     ), (-0.425325, -0.138196,  0.223606),
    (-0.154508, -0.475528,  0.0     ), ( 0.154508, -0.475528,  0.0     ),
    ( 0.0     , -0.447213,  0.223606), ( 0.404508, -0.293892,  0.0     ),
    ( 0.5     ,  0.0     ,  0.0     ), ( 0.425325, -0.138196,  0.223606),
    ( 0.404508,  0.293892,  0.0     ), ( 0.154508,  0.475528,  0.0     ),
    ( 0.262865,  0.361803,  0.223606), ( 0.0     ,  0.425325,  0.262865),
    (-0.404508,  0.131432,  0.262865), (-0.249999, -0.344095,  0.262865),
    ( 0.249999, -0.344095,  0.262865), ( 0.404508,  0.131432,  0.262865),
    ( 0.0     ,  0.0     ,  0.5     ), ( 0.154508,  0.212662,  0.425325),
    (-0.154508,  0.212662,  0.425325), ( 0.249999, -0.081230,  0.425325),
    ( 0.0     , -0.262865,  0.425325), (-0.249999, -0.081230,  0.425325),
)

SPHERE_FACE_VERTEX_INDICES = (
     2,  0,  1,  4,  1,  3,  5,  2,  4,  2,  1,  4,  6,  0,  2,  7,
     2,  5,  8,  6,  7,  6,  2,  7,  9,  0,  6, 10,  6,  8, 11,  9,
    10,  9,  6, 10, 12,  0,  9, 13,  9, 11, 14, 12, 13, 12,  9, 13,
     1,  0, 12, 15, 12, 14,  3,  1, 15,  1, 12, 15, 16,  3, 15, 17,
    15, 14, 18, 16, 17, 16, 15, 17, 19, 14, 13, 20, 13, 11, 21, 19,
    20, 19, 13, 20, 22, 11, 10, 23, 10,  8, 24, 22, 23, 22, 10, 23,
    25,  8,  7, 26,  7,  5, 27, 25, 26, 25,  7, 26, 28,  5,  4, 29,
     4,  3, 30, 28, 29, 28,  4, 29, 29,  3, 16, 31, 16, 18, 30, 29,
    31, 29, 16, 31, 17, 14, 19, 32, 19, 21, 18, 17, 32, 17, 19, 32,
    20, 11, 22, 33, 22, 24, 21, 20, 33, 20, 22, 33, 23,  8, 25, 34,
    25, 27, 24, 23, 34, 23, 25, 34, 26,  5, 28, 35, 28, 30, 27, 26,
    35, 26, 28, 35, 38, 36, 37, 31, 37, 30, 18, 38, 31, 38, 37, 31,
    37, 36, 39, 35, 39, 27, 30, 37, 35, 37, 39, 35, 39, 36, 40, 34,
    40, 24, 27, 39, 34, 39, 40, 34, 40, 36, 41, 33, 41, 21, 24, 40,
    33, 40, 41, 33, 41, 36, 38, 32, 38, 18, 21, 41, 32, 41, 38, 32,
)


resolution = (512, 384)
num_frames = 480
fps = 24
camera_pos = (0.0, 2.5, 5.0)
camera_front = (0.0, -0.5, -1.0)

renderer = warp.render.UsdRenderer("colors.usda")

box_color_base = np.array(
    (
        (1.0, 1.0, 1.0), (0.0, 0.0, 0.0),
        (1.0, 0.0, 0.0), (0.0, 0.0, 1.0),
        (0.0, 1.0, 0.0), (1.0, 0.0, 1.0),
        (1.0, 1.0, 0.0), (0.0, 1.0, 1.0),
    ),
)

for frame in range(num_frames):
    color = wp.sin(float(frame) * 0.05) * 0.5 + 0.5

    renderer.begin_frame(frame / num_frames)
    renderer.render_mesh(
        "box",
        BOX_POINTS,
        BOX_FACE_VERTEX_INDICES,
        pos=(-1.0, 0.0, 0.0),
        colors=box_color_base * ((color * 0.1, color * 0.1, color * 0.1),) * len(BOX_POINTS),
    )
    renderer.render_mesh(
        "sphere",
        SPHERE_POINTS,
        SPHERE_FACE_VERTEX_INDICES,
        pos=(1.0, 0.0, 0.0),
        colors=((0.5, 0.5, color),) * len(SPHERE_POINTS),
    )
    renderer.end_frame()

renderer.save()

Please let us know if you get a chance to build Warp from main and confirm whether it’s working for you.