[FEATURE] Support 2-channel (LA) textures in Rasterizer. (Genesis-Embodied-AI#1519)

Author: LeonLiu4

genesis/ext/pyrender/utils.py

@@ -87,17 +87,23 @@ def format_texture_source(texture, target_channels="RGB"):
             if texture.shape[2] == 1:
                 texture = np.repeat(texture, 3, axis=2)
             elif texture.shape[2] == 2:
-                raise ValueError("Cannot reformat 2-channel texture into RGB")
+                # Convert 2-channel texture to grayscale RGB by duplicating the first channel
+                texture = texture[:, :, (0, 0, 0)]
             else:
                 texture = texture[:, :, (0, 1, 2)]
         elif target_channels == "RGBA":
             if texture.shape[2] == 1:
                 texture = np.repeat(texture, 4, axis=2)
                 texture[:, :, 3] = 255
             elif texture.shape[2] == 2:
-                raise ValueError("Cannot reformat 2-channel texture into RGBA")
+                # Convert 2-channel texture (luminance + alpha) to RGBA by duplicating luminance to RGB
+                luminance = texture[:, :, :1]
+                alpha = texture[:, :, 1]
+                texture = np.empty((*texture.shape[:2], 4), dtype=texture.dtype)
+                texture[:, :, :3] = luminance
+                texture[:, :, 3] = alpha
             elif texture.shape[2] == 3:
-                tx = np.empty((texture.shape[0], texture.shape[1], 4), dtype=np.uint8)
+                tx = np.empty((*texture.shape[:2], 4), dtype=np.uint8)
                 tx[:, :, :3] = texture
                 tx[:, :, 3] = 255
                 texture = tx

tests/test_render.py

@@ -655,3 +655,20 @@ def test_madrona_batch_rendering(tmp_path, use_rasterizer, render_all_cameras, n
     for image_file in sorted(tmp_path.rglob("*.png")):
         with open(image_file, "rb") as f:
             assert f.read() == png_snapshot
+
+
+@pytest.mark.required
+@pytest.mark.parametrize("backend", [gs.cpu])
+def test_2_channels_luminance_alpha_textures(show_viewer):
+    scene = gs.Scene(
+        show_viewer=show_viewer,
+        show_FPS=False,
+    )
+    asset_path = get_hf_dataset(pattern="fridge/*")
+    fridge = scene.add_entity(
+        gs.morphs.URDF(
+            file=f"{asset_path}/fridge/fridge.urdf",
+            fixed=True,
+        )
+    )
+    scene.build()