1 files changed, 126 insertions, 0 deletions
diff --git a/intern/cycles/kernel/integrator/integrator_shade_light.h b/intern/cycles/kernel/integrator/integrator_shade_light.h
new file mode 100644
index 00000000000..05b530f9665
--- /dev/null
+++ b/intern/cycles/kernel/integrator/integrator_shade_light.h
@@ -0,0 +1,126 @@
+/*
+ * Copyright 2011-2021 Blender Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "kernel/kernel_accumulate.h"
+#include "kernel/kernel_emission.h"
+#include "kernel/kernel_light.h"
+#include "kernel/kernel_shader.h"
+
+CCL_NAMESPACE_BEGIN
+
+ccl_device_inline void integrate_light(INTEGRATOR_STATE_ARGS,
+                                       ccl_global float *ccl_restrict render_buffer)
+{
+  /* Setup light sample. */
+  Intersection isect ccl_optional_struct_init;
+  integrator_state_read_isect(INTEGRATOR_STATE_PASS, &isect);
+
+  float3 ray_P = INTEGRATOR_STATE(ray, P);
+  const float3 ray_D = INTEGRATOR_STATE(ray, D);
+  const float ray_time = INTEGRATOR_STATE(ray, time);
+
+  /* Advance ray beyond light. */
+  /* TODO: can we make this more numerically robust to avoid reintersecting the
+   * same light in some cases? */
+  const float3 new_ray_P = ray_offset(ray_P + ray_D * isect.t, ray_D);
+  INTEGRATOR_STATE_WRITE(ray, P) = new_ray_P;
+  INTEGRATOR_STATE_WRITE(ray, t) -= isect.t;
+
+  /* Set position to where the BSDF was sampled, for correct MIS PDF. */
+  const float mis_ray_t = INTEGRATOR_STATE(path, mis_ray_t);
+  ray_P -= ray_D * mis_ray_t;
+  isect.t += mis_ray_t;
+  INTEGRATOR_STATE_WRITE(path, mis_ray_t) = mis_ray_t + isect.t;
+
+  LightSample ls ccl_optional_struct_init;
+  const bool use_light_sample = light_sample_from_intersection(kg, &isect, ray_P, ray_D, &ls);
+
+  if (!use_light_sample) {
+    return;
+  }
+
+  /* Use visibility flag to skip lights. */
+#ifdef __PASSES__
+  const uint32_t path_flag = INTEGRATOR_STATE(path, flag);
+
+  if (ls.shader & SHADER_EXCLUDE_ANY) {
+    if (((ls.shader & SHADER_EXCLUDE_DIFFUSE) && (path_flag & PATH_RAY_DIFFUSE)) ||
+        ((ls.shader & SHADER_EXCLUDE_GLOSSY) &&
+         ((path_flag & (PATH_RAY_GLOSSY | PATH_RAY_REFLECT)) ==
+          (PATH_RAY_GLOSSY | PATH_RAY_REFLECT))) ||
+        ((ls.shader & SHADER_EXCLUDE_TRANSMIT) && (path_flag & PATH_RAY_TRANSMIT)) ||
+        ((ls.shader & SHADER_EXCLUDE_SCATTER) && (path_flag & PATH_RAY_VOLUME_SCATTER)))
+      return;
+  }
+#endif
+
+  /* Evaluate light shader. */
+  /* TODO: does aliasing like this break automatic SoA in CUDA? */
+  ShaderDataTinyStorage emission_sd_storage;
+  ShaderData *emission_sd = AS_SHADER_DATA(&emission_sd_storage);
+  float3 light_eval = light_sample_shader_eval(INTEGRATOR_STATE_PASS, emission_sd, &ls, ray_time);
+  if (is_zero(light_eval)) {
+    return;
+  }
+
+  /* MIS weighting. */
+  if (!(path_flag & PATH_RAY_MIS_SKIP)) {
+    /* multiple importance sampling, get regular light pdf,
+     * and compute weight with respect to BSDF pdf */
+    const float mis_ray_pdf = INTEGRATOR_STATE(path, mis_ray_pdf);
+    const float mis_weight = power_heuristic(mis_ray_pdf, ls.pdf);
+    light_eval *= mis_weight;
+  }
+
+  /* Write to render buffer. */
+  const float3 throughput = INTEGRATOR_STATE(path, throughput);
+  kernel_accum_emission(INTEGRATOR_STATE_PASS, throughput, light_eval, render_buffer);
+}
+
+ccl_device void integrator_shade_light(INTEGRATOR_STATE_ARGS,
+                                       ccl_global float *ccl_restrict render_buffer)
+{
+  PROFILING_INIT(kg, PROFILING_SHADE_LIGHT_SETUP);
+
+  integrate_light(INTEGRATOR_STATE_PASS, render_buffer);
+
+  /* TODO: we could get stuck in an infinite loop if there are precision issues
+   * and the same light is hit again.
+   *
+   * As a workaround count this as a transparent bounce. It makes some sense
+   * to interpret lights as transparent surfaces (and support making them opaque),
+   * but this needs to be revisited. */
+  uint32_t transparent_bounce = INTEGRATOR_STATE(path, transparent_bounce) + 1;
+  INTEGRATOR_STATE_WRITE(path, transparent_bounce) = transparent_bounce;
+
+  if (transparent_bounce >= kernel_data.integrator.transparent_max_bounce) {
+    INTEGRATOR_PATH_TERMINATE(DEVICE_KERNEL_INTEGRATOR_SHADE_LIGHT);
+    return;
+  }
+  else {
+    INTEGRATOR_PATH_NEXT(DEVICE_KERNEL_INTEGRATOR_SHADE_LIGHT,
+                         DEVICE_KERNEL_INTEGRATOR_INTERSECT_CLOSEST);
+    return;
+  }
+
+  /* TODO: in some cases we could continue directly to SHADE_BACKGROUND, but
+   * probably that optimization is probably not practical if we add lights to
+   * scene geometry. */
+}
+
+CCL_NAMESPACE_END