Add adaptive_sampling integrator

src/integrators/tests/test_adaptive.py

@@ -0,0 +1,30 @@
+import drjit as dr
+import mitsuba as mi
+import pytest
+
+def test_adaptive_sampling(variants_vec_rgb):
+    pytest.skip()
+    scene = mi.load_dict(mi.cornell_box())
+
+    adaptive_integrator = mi.load_dict({
+        'type': 'adaptive_sampling',
+        'threshold': 0.05,
+        'pass_spp': 16,
+        'nested': scene.integrator()
+    })
+
+    def callback(pass_i: int,
+                 accum_spp: int,
+                 pass_spp: int,
+                 img: mi.TensorXf,
+                 odd_img: mi.TensorXf,
+                 error: mi.TensorXf,
+                 active: mi.TensorXf):
+        print(f'Adaptive sampling pass {pass_i}, rendering {dr.count(active)} pixels with {pass_spp} spp.')
+        return True
+
+    adaptive_integrator.set_callback(callback)
+
+    img = mi.render(scene, integrator=adaptive_integrator, spp=512)
+    # img = mi.render(scene, integrator=scene.integrator(), spp=512)
+    # mi.Bitmap(img).write('output.exr')

src/python/python/ad/integrators/__init__.py

@@ -6,6 +6,7 @@
     # List of submodules to import
     submodules = [
         'common',
+        'adaptive',
         'prb_basic',
         'prb',
         'prbvolpath',