6 files changed, 72 insertions, 3 deletions
diff --git a/intern/cycles/blender/addon/ui.py b/intern/cycles/blender/addon/ui.py
index 7036e58f6fb..f763fe0eb0b 100644
--- a/intern/cycles/blender/addon/ui.py
+++ b/intern/cycles/blender/addon/ui.py
@@ -1880,6 +1880,12 @@ class CYCLES_RENDER_PT_bake(CyclesButtonsPanel, Panel):
             layout.prop(rd, "use_bake_multires")
             layout.prop(cscene, "bake_type")
 
+        if not rd.use_bake_multires and cscene.bake_type not in {
+                "AO", "POSITION", "NORMAL", "UV", "ROUGHNESS", "ENVIRONMENT"}:
+            row = layout.row()
+            row.prop(cbk, "view_from")
+            row.active = scene.camera is not None
+
 
 class CYCLES_RENDER_PT_bake_influence(CyclesButtonsPanel, Panel):
     bl_label = "Influence"
diff --git a/intern/cycles/blender/camera.cpp b/intern/cycles/blender/camera.cpp
index 6926c833096..d7def9fdb7c 100644
--- a/intern/cycles/blender/camera.cpp
+++ b/intern/cycles/blender/camera.cpp
@@ -2,6 +2,7 @@
  * Copyright 2011-2022 Blender Foundation */
 
 #include "scene/camera.h"
+#include "scene/bake.h"
 #include "scene/scene.h"
 
 #include "blender/sync.h"
@@ -592,6 +593,11 @@ void BlenderSync::sync_camera(BL::RenderSettings &b_render,
     blender_camera_from_object(&bcam, b_engine, b_ob);
     b_engine.camera_model_matrix(b_ob, bcam.use_spherical_stereo, b_ob_matrix);
     bcam.matrix = get_transform(b_ob_matrix);
+    scene->bake_manager->set_use_camera(b_render.bake().view_from() ==
+                                        BL::BakeSettings::view_from_ACTIVE_CAMERA);
+  }
+  else {
+    scene->bake_manager->set_use_camera(false);
   }
 
   /* sync */
diff --git a/intern/cycles/kernel/integrator/init_from_bake.h b/intern/cycles/kernel/integrator/init_from_bake.h
index eca2c0b9ffb..15968670ac2 100644
--- a/intern/cycles/kernel/integrator/init_from_bake.h
+++ b/intern/cycles/kernel/integrator/init_from_bake.h
@@ -210,8 +210,51 @@ ccl_device bool integrator_init_from_bake(KernelGlobals kg,
 
     /* Setup ray. */
     Ray ray ccl_optional_struct_init;
-    ray.P = P + N;
-    ray.D = -N;
+
+    if (kernel_data.bake.use_camera) {
+      float3 D = camera_direction_from_point(kg, P);
+
+      const float DN = dot(D, N);
+
+      /* Nudge camera direction, so that the faces facing away from the camera still have
+       * somewhat usable shading. (Otherwise, glossy faces would be simply black.)
+       *
+       * The surface normal offset affects smooth surfaces. Lower values will make
+       * smooth surfaces more faceted, but higher values may show up from the camera
+       * at grazing angles.
+       *
+       * This value can actually be pretty high before it's noticeably wrong. */
+      const float surface_normal_offset = 0.2f;
+
+      /* Keep the ray direction at least `surface_normal_offset` "above" the smooth normal. */
+      if (DN <= surface_normal_offset) {
+        D -= N * (DN - surface_normal_offset);
+        D = normalize(D);
+      }
+
+      /* On the backside, just lerp towards the surface normal for the ray direction,
+       * as DN goes from 0.0 to -1.0. */
+      if (DN <= 0.0f) {
+        D = normalize(mix(D, N, -DN));
+      }
+
+      /* We don't want to bake the back face, so make sure the ray direction never
+       * goes behind the geometry (flat) normal. This is a failsafe, and should rarely happen. */
+      const float true_normal_epsilon = 0.00001f;
+
+      if (dot(D, Ng) <= true_normal_epsilon) {
+        D -= Ng * (dot(D, Ng) - true_normal_epsilon);
+        D = normalize(D);
+      }
+
+      ray.P = P + D;
+      ray.D = -D;
+    }
+    else {
+      ray.P = P + N;
+      ray.D = -N;
+    }
+
     ray.tmin = 0.0f;
     ray.tmax = FLT_MAX;
     ray.time = 0.5f;
diff --git a/intern/cycles/kernel/types.h b/intern/cycles/kernel/types.h
index f81e7843629..1469d915d15 100644
--- a/intern/cycles/kernel/types.h
+++ b/intern/cycles/kernel/types.h
@@ -1160,7 +1160,7 @@ typedef struct KernelBake {
   int use;
   int object_index;
   int tri_offset;
-  int pad1;
+  int use_camera;
 } KernelBake;
 static_assert_align(KernelBake, 16);
 
diff --git a/intern/cycles/scene/bake.cpp b/intern/cycles/scene/bake.cpp
index 1947b9d71a4..768e723b587 100644
--- a/intern/cycles/scene/bake.cpp
+++ b/intern/cycles/scene/bake.cpp
@@ -16,6 +16,7 @@ CCL_NAMESPACE_BEGIN
 BakeManager::BakeManager()
 {
   need_update_ = true;
+  use_camera_ = false;
 }
 
 BakeManager::~BakeManager()
@@ -38,6 +39,14 @@ void BakeManager::set(Scene *scene, const std::string &object_name_)
   need_update_ = true;
 }
 
+void BakeManager::set_use_camera(const bool use_camera)
+{
+  if (use_camera_ != use_camera) {
+    use_camera_ = use_camera;
+    need_update_ = true;
+  }
+}
+
 void BakeManager::device_update(Device * /*device*/,
                                 DeviceScene *dscene,
                                 Scene *scene,
@@ -49,6 +58,8 @@ void BakeManager::device_update(Device * /*device*/,
   KernelBake *kbake = &dscene->data.bake;
   memset(kbake, 0, sizeof(*kbake));
 
+  kbake->use_camera = use_camera_;
+
   if (!object_name.empty()) {
     scoped_callback_timer timer([scene](double time) {
       if (scene->update_stats) {
diff --git a/intern/cycles/scene/bake.h b/intern/cycles/scene/bake.h
index 0d90ece5628..e3f3911ab05 100644
--- a/intern/cycles/scene/bake.h
+++ b/intern/cycles/scene/bake.h
@@ -20,6 +20,8 @@ class BakeManager {
   void set(Scene *scene, const std::string &object_name);
   bool get_baking() const;
 
+  void set_use_camera(bool use_camera);
+
   void device_update(Device *device, DeviceScene *dscene, Scene *scene, Progress &progress);
   void device_free(Device *device, DeviceScene *dscene);
 
@@ -30,6 +32,7 @@ class BakeManager {
  private:
   bool need_update_;
   std::string object_name;
+  bool use_camera_;
 };
 
 CCL_NAMESPACE_END