intern/cycles/kernel/svm/bump.h

@@ -30,6 +30,10 @@ ccl_device_noinline void svm_node_enter_bump_eval(KernelGlobals kg,
 
     sd->P = P;
     sd->dP = differential_make_compact(dP);
+
+    /* Save the full differential, the compact form isn't enough for svm_node_set_bump. */
+    stack_store_float3(stack, offset + 4, dP.dx);
+    stack_store_float3(stack, offset + 7, dP.dy);
   }
 }
 

intern/cycles/kernel/svm/displace.h

@@ -15,6 +15,9 @@ ccl_device_noinline void svm_node_set_bump(KernelGlobals kg,
                                            ccl_private float *stack,
                                            uint4 node)
 {
+  uint out_offset, bump_state_offset, dummy;
+  svm_unpack_node_uchar4(node.w, &out_offset, &bump_state_offset, &dummy, &dummy);
+
 #ifdef __RAY_DIFFERENTIALS__
   IF_KERNEL_NODES_FEATURE(BUMP)
   {
@@ -25,7 +28,16 @@ ccl_device_noinline void svm_node_set_bump(KernelGlobals kg,
     float3 normal_in = stack_valid(normal_offset) ? stack_load_float3(stack, normal_offset) :
                                                     sd->N;
 
-    differential3 dP = differential_from_compact(sd->Ng, sd->dP);
+    /* If we have saved bump state, read the full differential from there.
+     * Just using the compact form in those cases leads to incorrect normals (see #111588). */
+    differential3 dP;
+    if (bump_state_offset == SVM_STACK_INVALID) {
+      dP = differential_from_compact(sd->Ng, sd->dP);
+    }
+    else {
+      dP.dx = stack_load_float3(stack, bump_state_offset + 4);
+      dP.dy = stack_load_float3(stack, bump_state_offset + 7);
+    }
 
     if (use_object_space) {
       object_inverse_normal_transform(kg, sd, &normal_in);
@@ -72,10 +84,10 @@ ccl_device_noinline void svm_node_set_bump(KernelGlobals kg,
       object_normal_transform(kg, sd, &normal_out);
     }
 
-    stack_store_float3(stack, node.w, normal_out);
+    stack_store_float3(stack, out_offset, normal_out);
   }
   else {
-    stack_store_float3(stack, node.w, zero_float3());
+    stack_store_float3(stack, out_offset, zero_float3());
   }
 #endif
 }

intern/cycles/kernel/svm/types.h

@@ -13,7 +13,7 @@ CCL_NAMESPACE_BEGIN
 /* SVM stack offsets with this value indicate that it's not on the stack */
 #define SVM_STACK_INVALID 255
 
-#define SVM_BUMP_EVAL_STATE_SIZE 4
+#define SVM_BUMP_EVAL_STATE_SIZE 10
 
 /* Nodes */
 

intern/cycles/scene/shader_nodes.cpp

@@ -6726,16 +6726,17 @@ void BumpNode::compile(SVMCompiler &compiler)
   ShaderOutput *normal_out = output("Normal");
 
   /* pack all parameters in the node */
-  compiler.add_node(NODE_SET_BUMP,
-                    compiler.encode_uchar4(compiler.stack_assign_if_linked(normal_in),
-                                           compiler.stack_assign(distance_in),
-                                           invert,
-                                           use_object_space),
-                    compiler.encode_uchar4(compiler.stack_assign(center_in),
-                                           compiler.stack_assign(dx_in),
-                                           compiler.stack_assign(dy_in),
-                                           compiler.stack_assign(strength_in)),
-                    compiler.stack_assign(normal_out));
+  compiler.add_node(
+      NODE_SET_BUMP,
+      compiler.encode_uchar4(compiler.stack_assign_if_linked(normal_in),
+                             compiler.stack_assign(distance_in),
+                             invert,
+                             use_object_space),
+      compiler.encode_uchar4(compiler.stack_assign(center_in),
+                             compiler.stack_assign(dx_in),
+                             compiler.stack_assign(dy_in),
+                             compiler.stack_assign(strength_in)),
+      compiler.encode_uchar4(compiler.stack_assign(normal_out), compiler.get_bump_state_offset()));
 }
 
 void BumpNode::compile(OSLCompiler &compiler)

intern/cycles/scene/svm.cpp

@@ -163,6 +163,7 @@ SVMCompiler::SVMCompiler(Scene *scene) : scene(scene)
   current_graph = NULL;
   background = false;
   mix_weight_offset = SVM_STACK_INVALID;
+  bump_state_offset = SVM_STACK_INVALID;
   compile_failed = false;
 
   /* This struct has one entry for every node, in order of ShaderNodeType definition. */
@@ -784,9 +785,8 @@ void SVMCompiler::compile_type(Shader *shader, ShaderGraph *graph, ShaderType ty
   }
 
   /* for the bump shader we need add a node to store the shader state */
-  bool need_bump_state = (type == SHADER_TYPE_BUMP) &&
-                         (shader->get_displacement_method() == DISPLACE_BOTH);
-  int bump_state_offset = SVM_STACK_INVALID;
+  const bool need_bump_state = (type == SHADER_TYPE_BUMP) &&
+                               (shader->get_displacement_method() == DISPLACE_BOTH);
   if (need_bump_state) {
     bump_state_offset = stack_find_offset(SVM_BUMP_EVAL_STATE_SIZE);
     add_node(NODE_ENTER_BUMP_EVAL, bump_state_offset);
@@ -846,6 +846,7 @@ void SVMCompiler::compile_type(Shader *shader, ShaderGraph *graph, ShaderType ty
   /* add node to restore state after bump shader has finished */
   if (need_bump_state) {
     add_node(NODE_LEAVE_BUMP_EVAL, bump_state_offset);
+    bump_state_offset = SVM_STACK_INVALID;
   }
 
   /* if compile failed, generate empty shader */

intern/cycles/scene/svm.h

@@ -106,6 +106,10 @@ class SVMCompiler {
   {
     return mix_weight_offset;
   }
+  uint get_bump_state_offset()
+  {
+    return bump_state_offset;
+  }
 
   ShaderType output_type()
   {
@@ -222,6 +226,7 @@ class SVMCompiler {
   Stack active_stack;
   int max_stack_use;
   uint mix_weight_offset;
+  uint bump_state_offset;
   bool compile_failed;
 };