[FEATURE] Multi env camera sensor (pyrender and Luisa)

[YilingQiao]

Summary

Adds support for cameras (both attached and static) to render different viewpoints per environment when n_envs > 1. Previously, all environments rendered from the same camera pose. Here are batched rendered results for rasterizer and raytracer

Implementation

Core Change: Added _get_camera_transforms_per_env(n_envs) method in camera.py that computes unique camera transforms for each environment:

• For attached cameras: transforms local position with each env's link pose, computes proper lookat-based view
• For static cameras: returns same transform for all envs

Rasterizer (rasterizer.py, pyrender/renderer.py):

• Added camera_poses parameter to render pipeline
• Updates camera view matrix per-env inside existing env loop
• Uses instanced rendering - no performance penalty

Raytracer (raytracer.py):

• Added update_scene_for_env(env_idx) method that updates shape _0 with transforms from specified env
• Hides other env shapes by moving them off-screen
• Renders sequentially (O(N) slower, documented)

Files Changed

• genesis/engine/sensors/camera.py - Core camera transform logic
• genesis/vis/rasterizer.py - Pass camera_poses to pyrender
• genesis/ext/pyrender/renderer.py - Per-env camera matrix updates
• genesis/vis/raytracer.py - Per-env scene updates

Testing

# Run all camera tests (10 tests)
pytest tests/test_sensor_camera.py -v --forked

# Run example
python examples/sensors/camera_multi_env.py -n 4  # Rasterizer
python examples/sensors/camera_multi_env.py -n 4 -r raytracer  # Raytracer

Test Coverage

• test_rasterizer_camera_sensor_attached_per_env_pose - Attached camera different poses per env
• test_raytracer_camera_sensor_attached_per_env_pose - Same for raytracer
• test_*_different_poses - Static camera sees different object positions per env

Checklist:

• I read the CONTRIBUTING document.
• I followed the Submitting Code Changes section of CONTRIBUTING document.
• I tagged the title correctly (including BUG FIX/FEATURE/MISC/BREAKING)
• I updated the documentation accordingly or no change is needed.
• I tested my changes and added instructions on how to test it for reviewers.

• I have added tests to cover my changes.
• All new and existing tests passed.