def integrator_sample(scene, sampler, rays, medium, active=True): si = scene.ray_intersect(rays) active = si.is_valid() & active # Visible emitters emitter_vis = si.emitter(scene, active) result = ek.select(active, Emitter.eval_vec(emitter_vis, si, active), Vector3f(0.0)) ctx = BSDFContext() bsdf = si.bsdf(rays) # Emitter sampling sample_emitter = active & has_flag(BSDF.flags_vec(bsdf), BSDFFlags.Smooth) ds, emitter_val = scene.sample_emitter_direction(si, sampler.next_2d(sample_emitter), True, sample_emitter) active_e = sample_emitter & ek.neq(ds.pdf, 0.0) wo = si.to_local(ds.d) bsdf_val = BSDF.eval_vec(bsdf, ctx, si, wo, active_e) bsdf_pdf = BSDF.pdf_vec(bsdf, ctx, si, wo, active_e) mis = ek.select(ds.delta, Float(1), mis_weight(ds.pdf, bsdf_pdf)) result += ek.select(active_e, emitter_val * bsdf_val * mis, Vector3f(0)) # BSDF sampling active_b = active bs, bsdf_val = BSDF.sample_vec(bsdf, ctx, si, sampler.next_1d(active), sampler.next_2d(active), active_b) si_bsdf = scene.ray_intersect(si.spawn_ray(si.to_world(bs.wo)), active_b) emitter = si_bsdf.emitter(scene, active_b) active_b &= ek.neq(emitter, 0) emitter_val = Emitter.eval_vec(emitter, si_bsdf, active_b) delta = has_flag(bs.sampled_type, BSDFFlags.Delta) ds = DirectionSample3f(si_bsdf, si) ds.object = emitter emitter_pdf = ek.select(delta, Float(0), scene.pdf_emitter_direction(si, ds, active_b)) result += ek.select(active_b, bsdf_val * emitter_val * mis_weight(bs.pdf, emitter_pdf), Vector3f(0)) return result, si.is_valid(), ek.select(si.is_valid(), si.t, Float(0.0))
def render_sample(scene, sampler, rays, bdata, heightmap_pybind, bssrdf=None): """ Sample RTE TODO: Support multi channel sampling Args: scene: Target scene object sampler: Sampler object for random number rays: Given rays for sampling bdata: BSSRDF Data object heightmap_pybind: Object for getting height map around incident position. Refer src/librender/python/heightmap.cpp Returns: result: Sampling RTE result valid_rays: Mask data whether rays are valid or not scatter: Scatter components of Sampling RTE result non_scatter: Non scatter components of Sampling RTE result invalid_sample: Sampling RTE result with invalid sampled data by VAEBSSRDF """ eta = Float(1.0) emission_weight = Float(1.0) throughput = Spectrum(1.0) result = Spectrum(0.0) scatter = Spectrum(0.0) non_scatter = Spectrum(0.0) invalid_sample = Spectrum(0.0) active = True is_bssrdf = False ##### First interaction ##### si = scene.ray_intersect(rays, active) active = si.is_valid() & active valid_rays = si.is_valid() emitter = si.emitter(scene, active) depth = 0 # Set channel # At and after evaluating BSSRDF, a ray consider only this one channel n_channels = 3 channel = UInt32( ek.min(sampler.next_1d(active) * n_channels, n_channels - 1)) d_out_local = Vector3f().zero() d_out_pdf = Float(0) sss = Mask(False) while (True): depth += 1 if config.aovs and depth == 2: sss = is_bssrdf ##### Interaction with emitters ##### emission_val = emission_weight * throughput * Emitter.eval_vec( emitter, si, active) result += ek.select(active, emission_val, Spectrum(0.0)) invalid_sample += ek.select(active, emission_val, Spectrum(0.0)) scatter += ek.select(active & sss, emission_val, Spectrum(0.0)) non_scatter += ek.select(active & ~sss, emission_val, Spectrum(0.0)) active = active & si.is_valid() # Process russian roulette if depth > config.rr_depth: q = ek.min(ek.hmax(throughput) * ek.sqr(eta), 0.95) active = active & (sampler.next_1d(active) < q) throughput *= ek.rcp(q) # Stop if the number of bouces exceeds the given limit bounce, or # all rays are invalid. latter check is done only when the limit # bounce is infinite if depth >= config.max_depth: break ##### Emitter sampling ##### bsdf = si.bsdf(rays) ctx = BSDFContext() active_e = active & has_flag(BSDF.flags_vec(bsdf), BSDFFlags.Smooth) ds, emitter_val = scene.sample_emitter_direction( si, sampler.next_2d(active_e), True, active_e) active_e &= ek.neq(ds.pdf, 0.0) # Query the BSDF for that emitter-sampled direction wo = si.to_local(ds.d) bsdf_val = BSDF.eval_vec(bsdf, ctx, si, wo, active_e) # Determine density of sampling that same direction using BSDF sampling bsdf_pdf = BSDF.pdf_vec(bsdf, ctx, si, wo, active_e) mis = ek.select(ds.delta, Float(1), mis_weight(ds.pdf, bsdf_pdf)) emission_val = mis * throughput * bsdf_val * emitter_val result += ek.select(active, emission_val, Spectrum(0.0)) invalid_sample += ek.select(active, emission_val, Spectrum(0.0)) scatter += ek.select(active & sss, emission_val, Spectrum(0.0)) non_scatter += ek.select(active & ~sss, emission_val, Spectrum(0.0)) ##### BSDF sampling ##### bs, bsdf_val = BSDF.sample_vec(bsdf, ctx, si, sampler.next_1d(active), sampler.next_2d(active), active) ##### BSSRDF replacing ##### if (config.enable_bssrdf): # Replace bsdf samples by ones of BSSRDF bs.wo = ek.select(is_bssrdf, d_out_local, bs.wo) bs.pdf = ek.select(is_bssrdf, d_out_pdf, bs.pdf) bs.sampled_component = ek.select(is_bssrdf, UInt32(1), bs.sampled_component) bs.sampled_type = ek.select(is_bssrdf, UInt32(+BSDFFlags.DeltaTransmission), bs.sampled_type) ############################ throughput *= ek.select(is_bssrdf, Float(1.0), bsdf_val) active &= ek.any(ek.neq(throughput, 0)) eta *= bs.eta # Intersect the BSDF ray against the scene geometry rays = RayDifferential3f(si.spawn_ray(si.to_world(bs.wo))) si_bsdf = scene.ray_intersect(rays, active) ##### Checking BSSRDF ##### if (config.enable_bssrdf): # Whether the BSDF is BSS RDF or not? is_bssrdf = (active & has_flag(BSDF.flags_vec(bsdf), BSDFFlags.BSSRDF) & (Frame3f.cos_theta(bs.wo) < Float(0.0)) & (Frame3f.cos_theta(si.wi) > Float(0.0))) # Decide whether we should use 0-scattering or multiple scattering is_zero_scatter = utils_render.check_zero_scatter( sampler, si_bsdf, bs, channel, is_bssrdf) is_bssrdf = is_bssrdf & ~is_zero_scatter throughput *= ek.select(is_bssrdf, ek.sqr(bs.eta), Float(1.0)) ########################### ###### Process for BSSRDF ###### if (config.enable_bssrdf and not ek.none(is_bssrdf)): # Get projected samples from BSSRDF projected_si, project_suc, abs_prob = bssrdf.sample_bssrdf( scene, bsdf, bs, si, bdata, heightmap_pybind, channel, is_bssrdf) if config.visualize_invalid_sample and (depth <= 1): active = active & (~is_bssrdf | project_suc) invalid_sample += ek.select((is_bssrdf & (~project_suc)), Spectrum([100, 0, 0]), Spectrum(0.0)) # Sample outgoing direction from projected position d_out_local, d_out_pdf = utils_render.resample_wo( sampler, is_bssrdf) # Apply absorption probability throughput *= ek.select(is_bssrdf, Spectrum(1) - abs_prob, Spectrum(1)) # Replace interactions by sampled ones from BSSRDF si_bsdf = SurfaceInteraction3f().masked_si(si_bsdf, projected_si, is_bssrdf) ################################ # Determine probability of having sampled that same # direction using emitter sampling emitter = si_bsdf.emitter(scene, active) ds = DirectionSample3f(si_bsdf, si) ds.object = emitter delta = has_flag(bs.sampled_type, BSDFFlags.Delta) emitter_pdf = ek.select(delta, Float(0.0), scene.pdf_emitter_direction(si, ds)) emission_weight = mis_weight(bs.pdf, emitter_pdf) si = si_bsdf return result, valid_rays, scatter, non_scatter, invalid_sample