PROCITY/pipeline/contact_sheet.py

#!/usr/bin/env python3
"""Render a labelled contact sheet of many GLBs in ONE Blender run — the eyeball tool.

The house rule is "always eyeball the thumbnails", and R41 §41.2 imports ~150 assets across three
libraries. One Blender startup per asset would cost more than the work; this lays every GLB out on
a grid in a single scene, one camera, one render, with a Blender text label and a metre reference
under each. Blender startup is the slow part, so 48 assets cost about what 2 do.

Every tile is framed to the SAME world scale by default (`--absolute`), which is the only way a
contact sheet can answer "is this metre-correct" — a per-tile auto-zoom makes a 0.2 m stool and a
2 m fridge look identical, which is exactly how a wrong scale ships. A 1 m grid square sits under
each asset as the ruler.

    BL=/Applications/Blender.app/Contents/MacOS/Blender
    "$BL" --background --python pipeline/contact_sheet.py -- OUT.png GLB [GLB ...]
    "$BL" --background --python pipeline/contact_sheet.py -- OUT.png --cols 8 --tile 320 DIR/*.glb

Options (after OUT.png, in any order among the file list):
    --cols N      tiles per row (default: ceil(sqrt(n)))
    --tile N      pixel size per tile (default 256)
    --fit         per-tile auto-zoom instead of one shared scale (looks prettier, lies about size)
    --title TEXT  caption drawn at the top of the sheet
"""
import bpy, sys, os, math
from mathutils import Vector

ARGV = sys.argv[sys.argv.index("--") + 1:]
OUT = ARGV[0]
rest = ARGV[1:]
COLS = TILE = None
FIT = False
TITLE = ""
files = []
i = 0
while i < len(rest):
    a = rest[i]
    if a == "--cols":
        COLS = int(rest[i + 1]); i += 2
    elif a == "--tile":
        TILE = int(rest[i + 1]); i += 2
    elif a == "--title":
        TITLE = rest[i + 1]; i += 2
    elif a == "--fit":
        FIT = True; i += 1
    else:
        files.append(a); i += 1
TILE = TILE or 256
files = [f for f in files if f.lower().endswith(".glb")]
COLS = COLS or max(1, int(math.ceil(math.sqrt(len(files)))))
ROWS = int(math.ceil(len(files) / COLS))


def wipe():
    for o in list(bpy.data.objects):
        bpy.data.objects.remove(o, do_unlink=True)
    for c in list(bpy.data.collections):
        bpy.data.collections.remove(c)


def bounds(objs):
    lo = Vector((1e9,) * 3); hi = Vector((-1e9,) * 3)
    for o in objs:
        if o.type != 'MESH':
            continue
        for c in o.bound_box:
            w = o.matrix_world @ Vector(c)
            for k in range(3):
                lo[k] = min(lo[k], w[k]); hi[k] = max(hi[k], w[k])
    if lo.x > 1e8:
        return Vector((0, 0, 0)), Vector((0, 0, 0))
    return lo, hi


def label(text, x, y, size, colour=(0.1, 0.1, 0.1, 1)):
    cu = bpy.data.curves.new(type="FONT", name="lbl")
    cu.body = text
    cu.align_x = 'CENTER'
    cu.size = size
    ob = bpy.data.objects.new("lbl", cu)
    ob.location = (x, y, 0)
    m = bpy.data.materials.new("lblmat")
    m.use_nodes = True
    bsdf = m.node_tree.nodes.get("Principled BSDF")
    bsdf.inputs["Base Color"].default_value = colour
    bsdf.inputs["Roughness"].default_value = 1.0
    ob.data.materials.append(m)
    bpy.context.scene.collection.objects.link(ob)
    return ob


def main():
    wipe()
    scn = bpy.context.scene
    THETA = math.radians(58)          # camera tilt from straight-down
    PITCH = 1.0                       # world metres between tile centres, ACROSS (x)
    # Rows are separated along world Y, which the tilted camera foreshortens by cos(THETA) ~ 0.53,
    # while object HEIGHT projects at sin(THETA) ~ 0.85. Using one pitch for both axes therefore
    # stacks every tall asset on top of the row behind it. Space the rows out by the reciprocal.
    PITCH_Y = PITCH / math.cos(THETA)

    # --- import every GLB, park it on the grid ------------------------------------------------
    placed = []
    for n, path in enumerate(files):
        r, c = divmod(n, COLS)
        before = set(bpy.data.objects)
        try:
            bpy.ops.import_scene.gltf(filepath=path)
        except Exception as e:
            print(f"IMPORT FAIL {path}: {e}")
            continue
        new = [o for o in bpy.data.objects if o not in before]
        roots = [o for o in new if o.parent is None]
        meshes = [o for o in new if o.type == 'MESH']
        if not meshes:
            for o in new:
                bpy.data.objects.remove(o, do_unlink=True)
            print(f"NO MESH {path}")
            continue
        lo, hi = bounds(meshes)
        size = max(hi.x - lo.x, hi.y - lo.y, hi.z - lo.z, 1e-4)
        cx, cy = (lo.x + hi.x) / 2, (lo.y + hi.y) / 2
        # scale: shared world scale (honest) or per-tile fit (pretty)
        s = (PITCH * 0.62) / size if FIT else 1.0
        tx, ty = c * PITCH, -r * PITCH_Y
        for o in roots:
            o.scale = (o.scale.x * s, o.scale.y * s, o.scale.z * s)
            o.location = (o.location.x * s + tx - cx * s,
                          o.location.y * s + ty - cy * s,
                          o.location.z * s - lo.z * s)
        placed.append((path, size, hi.z - lo.z, meshes))
        label(os.path.basename(path)[:-4][:26], tx, ty - PITCH * 0.50, PITCH * 0.052)
        label(f"{hi.x-lo.x:.2f} x {hi.y-lo.y:.2f} x {hi.z-lo.z:.2f} m",
              tx, ty - PITCH * 0.60, PITCH * 0.042, (0.30, 0.30, 0.38, 1))

    # --- a 1 m reference square under every tile (the ruler) -----------------------------------
    if not FIT:
        for n in range(len(placed)):
            r, c = divmod(n, COLS)
            bpy.ops.mesh.primitive_plane_add(size=1.0, location=(c * PITCH, -r * PITCH_Y, -0.002))
            p = bpy.context.object
            m = bpy.data.materials.new("grid")
            m.use_nodes = True
            b = m.node_tree.nodes.get("Principled BSDF")
            b.inputs["Base Color"].default_value = (0.80, 0.80, 0.84, 1)
            b.inputs["Roughness"].default_value = 1.0
            p.data.materials.append(m)

    # --- backdrop, light, camera ----------------------------------------------------------------
    W = (COLS - 1) * PITCH
    H = (ROWS - 1) * PITCH_Y
    tall = max((t[2] for t in placed), default=1.0)
    bpy.ops.mesh.primitive_plane_add(size=max(W, H) * 4 + 40, location=(W / 2, -H / 2, -0.004))
    bg = bpy.context.object
    m = bpy.data.materials.new("bg")
    m.use_nodes = True
    b = m.node_tree.nodes.get("Principled BSDF")
    b.inputs["Base Color"].default_value = (0.94, 0.94, 0.96, 1)
    b.inputs["Roughness"].default_value = 1.0
    bg.data.materials.append(m)

    scn.world.use_nodes = True
    scn.world.node_tree.nodes["Background"].inputs[0].default_value = (0.9, 0.92, 0.96, 1)
    scn.world.node_tree.nodes["Background"].inputs[1].default_value = 0.85
    bpy.ops.object.light_add(type='SUN', location=(W / 2 + 3, -H / 2 - 4, 8 + tall))
    sun = bpy.context.object
    sun.data.energy = 1.9
    sun.rotation_euler = (math.radians(52), 0, math.radians(38))

    # A CONTACT SHEET IS A COLOUR JUDGEMENT, so it must not go through a film emulation.
    # Blender's default view transform (AgX in 5.x) desaturates hard: the first pass of the
    # art_incoming props read as bleached white and looked like the vertex-colour transfer had
    # failed, when measuring COLOR_0 in the exported GLBs showed the means intact to within 3%.
    # The tool was lying, not the asset. Standard = what you see is what is in the file.
    scn.view_settings.view_transform = 'Standard'
    scn.view_settings.look = 'None'

    # Aim the camera AT the grid centre. A camera rotated theta about X looks along
    # (0, sin theta, -cos theta), so it must sit back along the reverse of that ray from the target
    # -- an arbitrary offset misses by t*sin(theta) and renders an empty backdrop (this tool's
    # first take came back blank exactly that way).
    tgt = Vector((W / 2, -H / 2 - PITCH * 0.15, PITCH * 0.20))
    cam_d = (max(W, H) + tall) * 3.0 + 10.0
    bpy.ops.object.camera_add(location=(tgt.x,
                                        tgt.y - cam_d * math.sin(THETA),
                                        tgt.z + cam_d * math.cos(THETA)))
    cam = bpy.context.object
    cam.data.type = 'ORTHO'
    cam.data.clip_end = cam_d * 4
    cam.rotation_euler = (THETA, 0, 0)
    scn.camera = cam

    # World extent the frame must contain. Screen-vertical mixes the ground span BETWEEN row
    # centres ((ROWS-1) gaps, each PITCH_Y foreshortened by cos = PITCH) with the tallest object's
    # height (x sin) and one label gutter. Counting a gutter PER ROW instead of between rows
    # over-estimates badly at ROWS=1 and renders everything as postage stamps.
    need_w = COLS * PITCH * 1.02
    need_h = (ROWS - 1) * PITCH + tall * math.sin(THETA) + PITCH * 0.75 \
        + (PITCH * 0.42 if TITLE else 0.0)
    res_x = int(COLS * TILE)
    res_y = max(TILE // 2, int(res_x * need_h / need_w))
    # ortho_scale governs the LARGER pixel dimension; solve so BOTH fit.
    if res_x >= res_y:
        cam.data.ortho_scale = max(need_w, need_h * res_x / res_y)
    else:
        cam.data.ortho_scale = max(need_h, need_w * res_y / res_x)

    if TITLE:
        # well clear of row 0: tall assets project upward in screen space from y=0, so a title
        # parked at +0.6 m lands on top of them.
        label(TITLE, W / 2, PITCH_Y * 0.72 + tall, PITCH * 0.085, (0.05, 0.05, 0.1, 1))

    # Blender 5.x renamed the EEVEE enum back to BLENDER_EEVEE; keep both spellings working.
    engines = scn.bl_rna.properties["render"].fixed_type.properties["engine"].enum_items.keys() \
        if False else ('BLENDER_EEVEE', 'BLENDER_EEVEE_NEXT')
    for e in engines:
        try:
            scn.render.engine = e
            break
        except TypeError:
            continue
    scn.render.film_transparent = False
    scn.render.resolution_x = res_x
    scn.render.resolution_y = res_y
    scn.render.image_settings.file_format = 'PNG'
    scn.render.filepath = os.path.abspath(OUT)
    os.makedirs(os.path.dirname(os.path.abspath(OUT)), exist_ok=True)
    bpy.ops.render.render(write_still=True)
    print(f"SHEET {OUT}  {len(placed)}/{len(files)} rendered  {COLS}x{ROWS}")


main()