blender-rendering

Blender Rendering Skill

Version: 2.1.0 Last Updated: 2026-09-10 Dependencies: Blender 5.1+

Breaking Changes (4.5+ / 5.1+)

import bpy

# 1. EEVEE engine renamed (complete removal)
bpy.context.scene.render.engine = 'BLENDER_EEVEE_NEXT'  # Not 'BLENDER_EEVEE'

# 2. Bloom removed from EEVEE - use Compositor Glare node
# scene.eevee.use_bloom = True  <- AttributeError in 4.5.3+

# 3. SSR removed - use ray tracing
# scene.eevee.use_ssr = True  <- AttributeError
scene.eevee.use_raytracing = True  # replacement

# 4. Principled BSDF input names changed
bsdf.inputs["Transmission Weight"].default_value = 1.0   # was "Transmission"
bsdf.inputs["Subsurface Weight"].default_value = 0.2     # was "Subsurface"
bsdf.inputs["Emission Color"].default_value = (1,1,1,1)  # was "Emission"

# 5. Cycles settings
cycles = bpy.context.scene.cycles    # Direct access - no import needed
cycles.samples = 128

EEVEE Next / Cycles facts (loop-gauntlet round-2/3 lessons, 2026-09-10)

• Emissive meshes do not illuminate anything in EEVEE Next. A mesh with an emission shader (LED strips, glowing coves) renders bright itself but casts no light on neighbouring surfaces. If a reference shows spill from a glowing surface, place a real light (area light along the strip) - do not expect the emissive mesh to do it.
• Light-probe volume bake from a script/MCP execute context returns FINISHED without actually baking. bpy.ops.object.lightprobe_cache_bake(subset='ALL') completes in well under a second (even after waiting 60 s) with no visible change, and bpy.app.is_job_running has no LIGHT_BAKE enum to poll the bake state. Verify with an A/B render (probe object hidden vs visible) before relying on a bake - a script-triggered bake is unverifiable otherwise.
• Blender 5.1 LightProbeVolume properties: resolution_x, resolution_y, resolution_z, surfel_density (int), bake_samples, capture_world. The older grid_* names (grid_resolution_x, etc.) do not exist on this version - do not assume they do from older docs.
• Cycles light linking (Blender 4.0+): obj.light_linking.receiver_collection restricts which objects a light illuminates. Use it to give each zone (and each matched camera view) its own lights without those lights leaking into other zones - a chamber-only near-vertical sun, a lantern-only point light, a hallway-only steeper sun, and view-only fills can all coexist in one scene this way. The linking collection does not need to be in the view layer and may hold child collections.
• A strip emission value that reads as a clean bright line in EEVEE floods a room in Cycles. Moving an EEVEE-tuned rig to Cycles: strip emission strengths tuned for EEVEE (e.g. 40) need to drop roughly by a factor of 8 (to about 5) once Cycles adds real bounce light on top of them - re-measure with a mean-luminance readback rather than assuming a ratio.