Blender Lighting

Blender Lighting

Light scenes the way pros do: with structure, intent, and physically reasonable values.

The five light types

Default rule: Use Area lights for almost everything except the sun. Soft shadows come for free.

Decision tree

What's the mood?
├── Studio / commercial → Three-point lighting (key+fill+rim) + HDRI fill 0.3
├── Outdoor / sunlit → Sun + HDRI sky environment
├── Indoor cinematic → Sun through window + HDRI low + practicals (lamps as Point)
├── Dramatic / noir → Single Spot at high angle, no fill
├── Stylized / cartoon → Three-point with high contrast + saturated key color
└── Unsure → Three-point with HDRI grounding (works for 90% of cases)

Reference-look handoff

If the goal is to match an original/reference image rather than make a generally attractive render, chain-load reference-look-calibration. It owns measurement of hue/saturation/value, object extent, glow/aura color, and before/after look metrics. This skill should then apply the requested material/lighting/render changes within that calibrated target.

Recipes

Helper: aim_at(light, target) — required for subject-aware lighting

Recipe 1 below positions lights at fixed world coords with hardcoded rotations. That's fine for a generic 1m subject at the world origin. For ANY other subject (small jewellery, tall sword, sprawling building), you need lights aimed at the subject. Use this helper:

from mathutils import Vector

def aim_at(light_obj, target):
    """Aim a light at a world-space target.
    target may be a Vector or a tuple/list (x, y, z) or a Blender object.
    """
    target_pos = Vector(target.location) if hasattr(target, 'location') else Vector(target)
    direction = (target_pos - light_obj.location).normalized()
    light_obj.rotation_euler = direction.to_track_quat('-Z', 'Y').to_euler()

Helper: scene-aware light positioning

from mathutils import Vector

def compute_scene_bbox_center(meshes):
    """Average bbox center over a list of mesh objects (world space)."""
    import bpy
    deps = bpy.context.evaluated_depsgraph_get()
    all_verts = []
    for o in meshes:
        eval_obj = o.evaluated_get(deps)
        em = eval_obj.to_mesh()
        for v in em.vertices:
            all_verts.append(o.matrix_world @ v.co)
        eval_obj.to_mesh_clear()
    xs = [v.x for v in all_verts]
    ys = [v.y for v in all_verts]
    zs = [v.z for v in all_verts]
    center = Vector(((min(xs)+max(xs))/2, (min(ys)+max(ys))/2, (min(zs)+max(zs))/2))
    extent = max(max(xs)-min(xs), max(ys)-min(ys), max(zs)-min(zs))
    return center, extent

Recipe 0a — Subject-CLASS-aware three-point lighting (use this for orchestrator E2E)

Generic three-point lighting (Recipe 0b below) places lights at fixed energy ratios. That works for opaque subjects (chair, sword) but breaks for glass (rim washes out volume tint) and is too cool for wood (loses warmth).

Pass a subject_class hint to tune the setup:

import bpy, math
from mathutils import Vector

def aim_at(light_obj, target):
    target_pos = Vector(target.location) if hasattr(target, 'location') else Vector(target)
    direction = (target_pos - light_obj.location).normalized()
    light_obj.rotation_euler = direction.to_track_quat('-Z', 'Y').to_euler()

def apply_three_point(subject_class='metal'):
    """Configure 3-point lighting with subject-class-aware ratios.

    subject_class: 'metal' | 'glass' | 'wood' | 'fabric' | 'skin' | 'product' | 'metal' (default)
    """
    profiles = {
        'metal':   dict(ratio=(4.0, 1.0, 2.0), key_color=(1.0, 0.95, 0.85), fill_color=(0.85, 0.9, 1.0), rim_color=(0.7, 0.85, 1.0)),
        'glass':   dict(ratio=(3.0, 1.0, 1.2), key_color=(1.0, 0.98, 0.95), fill_color=(0.95, 0.95, 1.0), rim_color=(0.95, 0.95, 1.0)),
        'wood':    dict(ratio=(4.0, 1.0, 1.5), key_color=(1.0, 0.92, 0.78), fill_color=(0.95, 0.95, 1.0), rim_color=(0.85, 0.92, 1.0)),
        'fabric':  dict(ratio=(3.0, 1.0, 0.5), key_color=(1.0, 0.97, 0.92), fill_color=(0.92, 0.95, 1.0), rim_color=(0.95, 0.95, 1.0)),
        'skin':    dict(ratio=(4.0, 1.0, 1.0), key_color=(1.0, 0.93, 0.82), fill_color=(0.95, 0.96, 1.0), rim_color=(0.92, 0.92, 1.0)),
        'product': dict(ratio=(5.0, 1.0, 1.5), key_color=(1.0, 0.98, 0.95), fill_color=(0.98, 0.98, 1.0), rim_color=(0.98, 0.98, 1.0)),
    }
    p = profiles.get(subject_class, profiles['metal'])

    # Compute scene bbox
    subject_meshes = [o for o in bpy.data.objects if o.type == 'MESH' and o.name.startswith('GEO-')]
    deps = bpy.context.evaluated_depsgraph_get()
    all_verts = []
    for o in subject_meshes:
        eo = o.evaluated_get(deps); em = eo.to_mesh()
        for v in em.vertices: all_verts.append(o.matrix_world @ v.co)
        eo.to_mesh_clear()
    xs = [v.x for v in all_verts]; ys = [v.y for v in all_verts]; zs = [v.z for v in all_verts]
    center = Vector(((min(xs)+max(xs))/2, (min(ys)+max(ys))/2, (min(zs)+max(zs))/2))
    biggest = max(max(zs)-min(zs), max(xs)-min(xs))
    light_dist = max(biggest * 1.5, 1.0)

    # Energy scales with distance²
    base_energy = 100 * (light_dist / 1.5) ** 2
    key_e, fill_e, rim_e = (base_energy * r for r in p['ratio'])

    # Remove existing lights
    for o in list(bpy.data.objects):
        if o.type == 'LIGHT' and (o.name.startswith('LGT-key') or o.name.startswith('LGT-fill') or o.name.startswith('LGT-rim')):
            bpy.data.objects.remove(o, do_unlink=True)

    # KEY (warm, front-right above)
    key = bpy.data.objects.new('LGT-key', bpy.data.lights.new('LGT-key', type='AREA'))
    key.data.energy = key_e; key.data.size = 0.5; key.data.color = p['key_color']
    bpy.context.collection.objects.link(key)
    key.location = (center.x + light_dist*0.7, center.y - light_dist*0.7, center.z + light_dist*0.5)
    aim_at(key, center)

    # FILL (cool, opposite, weaker)
    fill = bpy.data.objects.new('LGT-fill', bpy.data.lights.new('LGT-fill', type='AREA'))
    fill.data.energy = fill_e; fill.data.size = 1.0; fill.data.color = p['fill_color']
    bpy.context.collection.objects.link(fill)
    fill.location = (center.x - light_dist*0.7, center.y - light_dist*0.5, center.z + light_dist*0.3)
    aim_at(fill, center)

    # RIM
    rim_type = 'AREA' if subject_class == 'glass' else 'SPOT'
    rim = bpy.data.objects.new('LGT-rim', bpy.data.lights.new('LGT-rim', type=rim_type))
    rim.data.energy = rim_e; rim.data.color = p['rim_color']
    if rim_type == 'AREA':
        rim.data.size = 1.5   # larger soft-source for glass
    else:
        rim.data.spot_size = math.radians(50)
    bpy.context.collection.objects.link(rim)