[Bf-blender-cvs] [11955d178a5] soc-2020-production-ready-light-tree: Fixed light tree construction.

[Sam Kottler]

Commit: 11955d178a522ba327538dd9c9e547033590008d
Author: Sam Kottler
Date:   Wed Jul 15 12:52:23 2020 -0600
Branches: soc-2020-production-ready-light-tree
https://developer.blender.org/rB11955d178a522ba327538dd9c9e547033590008d

Fixed light tree construction.

There was a bug in the light tree construction that caused mesh lights
to appear as brighter than other lamp lights.

===================================================================

M	intern/cycles/kernel/kernel_path_surface.h
M	intern/cycles/render/light.cpp
M	intern/cycles/render/light_tree.cpp

===================================================================

diff --git a/intern/cycles/kernel/kernel_path_surface.h b/intern/cycles/kernel/kernel_path_surface.h
index c783305d99f..e3746f69da5 100644
--- a/intern/cycles/kernel/kernel_path_surface.h
+++ b/intern/cycles/kernel/kernel_path_surface.h
@@ -113,7 +113,7 @@ ccl_device void accum_light_tree_contribution(KernelGlobals *kg,
         float cdf_L = 0.0f;
         float cdf_R = 0.0f;
         float prob = 0.0f;
-        int light;
+        int light = num_emitters - 1;
         for (int i = 1; i < num_emitters + 1; ++i) {
           prob = calc_light_importance(kg, P, N, offset, i - 1) * sum_inv;
           cdf_R = cdf_L + prob;
@@ -167,6 +167,7 @@ ccl_device void accum_light_tree_contribution(KernelGlobals *kg,
                                scale_factor);
 
       --stack_idx;
+      can_split = true;
       continue;
     }
     else {  // Interior node, choose which child(ren) to go down
@@ -220,6 +221,7 @@ ccl_device void accum_light_tree_contribution(KernelGlobals *kg,
         }
 
         //++stack_idx;
+        can_split = false;
         randu_stack[stack_idx] = randu;
         randv_stack[stack_idx] = randv;
         offset_stack[stack_idx] = offset;
diff --git a/intern/cycles/render/light.cpp b/intern/cycles/render/light.cpp
index 0a7eb493c36..ab556d40900 100644
--- a/intern/cycles/render/light.cpp
+++ b/intern/cycles/render/light.cpp
@@ -507,6 +507,7 @@ void LightManager::device_update_distribution(Device *device,
 
         /* todo: is there a better way than recalcing this? */
         /* have getters for the light tree that just accesses build_data? */
+
         BoundBox bbox = light_tree.compute_bbox(emissive_prims[j]);
         Orientation bcone = light_tree.compute_bcone(emissive_prims[j]);
         float energy = light_tree.compute_energy(emissive_prims[j]);
diff --git a/intern/cycles/render/light_tree.cpp b/intern/cycles/render/light_tree.cpp
index 8f60b9097ab..4523e01b953 100644
--- a/intern/cycles/render/light_tree.cpp
+++ b/intern/cycles/render/light_tree.cpp
@@ -269,37 +269,21 @@ float LightTree::compute_energy(const Primitive &prim)
     const Transform &tfm = scene->objects[prim.object_id]->tfm;
     float area = mesh->compute_triangle_area(triangle_id, tfm);
 
-    emission *= area * M_PI_F;
+    emission *= area * 4;
   }
   else {
     const Light *light = scene->lights[prim.lamp_id];
 
-    /* get emission from shader */
-    shader = light->shader;
-    bool is_constant_emission = shader->is_constant_emission(&emission);
-    if (!is_constant_emission) {
-      emission = make_float3(1.0f);
-    }
+    emission = light->strength;
 
-    /* calculate the total emission by integrating the emission over the
-     * the entire sphere of directions. */
+    /* calculate the max emission in a single direction. */
     if (light->type == LIGHT_POINT) {
-      emission *= M_4PI_F;
+      emission /= M_PI_F;
     }
     else if (light->type == LIGHT_SPOT) {
-      /* The emission is only non-zero within the cone and if spot_smooth
-       * is non-zero there will be a falloff. In this case, approximate
-       * the integral by considering a smaller cone without falloff. */
-      float spot_angle = light->spot_angle * 0.5f;
-      float spot_falloff_angle = spot_angle * (1.0f - light->spot_smooth);
-      float spot_middle_angle = (spot_angle + spot_falloff_angle) * 0.5f;
-      emission *= M_2PI_F * (1.0f - cosf(spot_middle_angle));
+      emission /= M_PI_F;
     }
     else if (light->type == LIGHT_AREA) {
-      float3 axisu = light->axisu * (light->sizeu * light->size);
-      float3 axisv = light->axisv * (light->sizev * light->size);
-      float area = len(axisu) * len(axisv);
-      emission *= area * M_PI_F;
     }
     else {
       /* LIGHT_DISTANT and LIGHT_BACKGROUND are handled separately */