Fix T52021: Shadow catcher renders wrong when catcher object is behind transparent...

Tweaked the path radiance summing and alpha to accommodate for possible contribution of
light by transparent surface bounces happening prior to shadow catcher intersection.

This commit will change the way how shadow catcher results looks when was behind semi
transparent object, but the old result seemed to be fully wrong: there were big artifacts
when alpha-overing the result on some actual footage.

diff --git a/intern/cycles/kernel/kernel_accumulate.h b/intern/cycles/kernel/kernel_accumulate.h
index 175bd6b9737daf999c6519b622781fe615a97639..9ed16aceb55d563e9b4c4841d3da1a89e2711cb8 100644 (file)
--- a/intern/cycles/kernel/kernel_accumulate.h
+++ b/intern/cycles/kernel/kernel_accumulate.h
@@ -220,7 +220,9 @@ ccl_device_inline void path_radiance_init(PathRadiance *L, int use_light_pass)
 #ifdef __SHADOW_TRICKS__
        L->path_total = make_float3(0.0f, 0.0f, 0.0f);
        L->path_total_shaded = make_float3(0.0f, 0.0f, 0.0f);
-       L->shadow_color = make_float3(0.0f, 0.0f, 0.0f);
+       L->shadow_background_color = make_float3(0.0f, 0.0f, 0.0f);
+       L->shadow_radiance_sum = make_float3(0.0f, 0.0f, 0.0f);
+       L->shadow_throughput = 0.0f;
 #endif
 
 #ifdef __DENOISING_FEATURES__
@@ -680,11 +682,12 @@ ccl_device_inline float3 path_radiance_sum_shadowcatcher(KernelGlobals *kg,
        const float shadow = path_radiance_sum_shadow(L);
        float3 L_sum;
        if(kernel_data.background.transparent) {
-               *alpha = 1.0f-shadow;
-               L_sum = make_float3(0.0f, 0.0f, 0.0f);
+               *alpha = 1.0f - L->shadow_throughput * shadow;
+               L_sum = L->shadow_radiance_sum;
        }
        else {
-               L_sum = L->shadow_color * shadow;
+               L_sum = L->shadow_background_color * L->shadow_throughput * shadow +
+                       L->shadow_radiance_sum;
        }
        return L_sum;
 }

diff --git a/intern/cycles/kernel/kernel_path.h b/intern/cycles/kernel/kernel_path.h
index fc093ad83194543e8916391f6bda3dde05324a1a..c340b3bc96859096b6cc1844436c8884185418bb 100644 (file)
--- a/intern/cycles/kernel/kernel_path.h
+++ b/intern/cycles/kernel/kernel_path.h
@@ -643,11 +643,16 @@ ccl_device_inline float kernel_path_integrate(KernelGlobals *kg,
 #ifdef __SHADOW_TRICKS__
                if((sd.object_flag & SD_OBJECT_SHADOW_CATCHER)) {
                        if(state.flag & PATH_RAY_CAMERA) {
-                               state.flag |= (PATH_RAY_SHADOW_CATCHER | PATH_RAY_SHADOW_CATCHER_ONLY | PATH_RAY_STORE_SHADOW_INFO);
+                               state.flag |= (PATH_RAY_SHADOW_CATCHER |
+                                              PATH_RAY_SHADOW_CATCHER_ONLY |
+                                              PATH_RAY_STORE_SHADOW_INFO);
                                state.catcher_object = sd.object;
                                if(!kernel_data.background.transparent) {
-                                       L->shadow_color = indirect_background(kg, &emission_sd, &state, &ray);
+                                       L->shadow_background_color =
+                                               indirect_background(kg, &emission_sd, &state, &ray);
                                }
+                               L->shadow_radiance_sum = path_radiance_clamp_and_sum(kg, L);
+                               L->shadow_throughput = average(throughput);
                        }
                }
                else {

diff --git a/intern/cycles/kernel/kernel_path_branched.h b/intern/cycles/kernel/kernel_path_branched.h
index 5f7f1a2ef1481823eddb362f28262966b31061a0..77d4f1df4472eb984d9c588076d9339374f62498 100644 (file)
--- a/intern/cycles/kernel/kernel_path_branched.h
+++ b/intern/cycles/kernel/kernel_path_branched.h
@@ -499,11 +499,16 @@ ccl_device float kernel_branched_path_integrate(KernelGlobals *kg,
 
 #ifdef __SHADOW_TRICKS__
                if((sd.object_flag & SD_OBJECT_SHADOW_CATCHER)) {
-                       state.flag |= (PATH_RAY_SHADOW_CATCHER | PATH_RAY_SHADOW_CATCHER_ONLY | PATH_RAY_STORE_SHADOW_INFO);
+                       state.flag |= (PATH_RAY_SHADOW_CATCHER |
+                                      PATH_RAY_SHADOW_CATCHER_ONLY |
+                                      PATH_RAY_STORE_SHADOW_INFO);
                        state.catcher_object = sd.object;
                        if(!kernel_data.background.transparent) {
-                               L->shadow_color = indirect_background(kg, &emission_sd, &state, &ray);
+                               L->shadow_background_color =
+                                       indirect_background(kg, &emission_sd, &state, &ray);
                        }
+                       L->shadow_radiance_sum = path_radiance_clamp_and_sum(kg, L);
+                       L->shadow_throughput = average(throughput);
                }
                else {
                        state.flag &= ~PATH_RAY_SHADOW_CATCHER_ONLY;

diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index 34affab1b9d03e559b2950b5c7417a10fe8431ba..37af98b32c7a19a8c4bb0c89b4e1d92881250ab6 100644 (file)
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -515,7 +515,13 @@ typedef ccl_addr_space struct PathRadiance {
        float3 path_total_shaded;
 
        /* Color of the background on which shadow is alpha-overed. */
-       float3 shadow_color;
+       float3 shadow_background_color;
+
+       /* Path radiance sum and throughput at the moment when ray hits shadow
+        * catcher object.
+        */
+       float3 shadow_radiance_sum;
+       float shadow_throughput;
 #endif
 
 #ifdef __DENOISING_FEATURES__

diff --git a/intern/cycles/kernel/split/kernel_holdout_emission_blurring_pathtermination_ao.h b/intern/cycles/kernel/split/kernel_holdout_emission_blurring_pathtermination_ao.h
index 670a557f084d33fd7a89ef90c89ea7fa6ea705b1..fec671be0167df81d0186484e25aa5f6fea08142 100644 (file)
--- a/intern/cycles/kernel/split/kernel_holdout_emission_blurring_pathtermination_ao.h
+++ b/intern/cycles/kernel/split/kernel_holdout_emission_blurring_pathtermination_ao.h
@@ -125,13 +125,21 @@ ccl_device void kernel_holdout_emission_blurring_pathtermination_ao(
 #ifdef __SHADOW_TRICKS__
                if((sd->object_flag & SD_OBJECT_SHADOW_CATCHER)) {
                        if(state->flag & PATH_RAY_CAMERA) {
-                               state->flag |= (PATH_RAY_SHADOW_CATCHER | PATH_RAY_SHADOW_CATCHER_ONLY | PATH_RAY_STORE_SHADOW_INFO);
+                               PathRadiance *L = &kernel_split_state.path_radiance[ray_index];
+                               state->flag |= (PATH_RAY_SHADOW_CATCHER |
+                                               PATH_RAY_SHADOW_CATCHER_ONLY |
+                                               PATH_RAY_STORE_SHADOW_INFO);
                                state->catcher_object = sd->object;
                                if(!kernel_data.background.transparent) {
-                                       PathRadiance *L = &kernel_split_state.path_radiance[ray_index];
                                        ccl_global Ray *ray = &kernel_split_state.ray[ray_index];
-                                       L->shadow_color = indirect_background(kg, &kernel_split_state.sd_DL_shadow[ray_index], state, ray);
+                                       L->shadow_background_color = indirect_background(
+                                               kg,
+                                               &kernel_split_state.sd_DL_shadow[ray_index],
+                                               state,
+                                               ray);
                                }
+                               L->shadow_radiance_sum = path_radiance_clamp_and_sum(kg, L);
+                               L->shadow_throughput = average(throughput);
                        }
                }
                else {