Fix T98392: GPU subdivision crash with knife tools

The face dots normals may not be always requested, thus leading to a
crash by null pointer dereference.

3 files changed, 32 insertions, 7 deletions

diff --git a/source/blender/draw/intern/draw_cache_impl_subdivision.cc b/source/blender/draw/intern/draw_cache_impl_subdivision.cc
index e3842ec2231..3a5593fa2a5 100644
--- a/source/blender/draw/intern/draw_cache_impl_subdivision.cc
+++ b/source/blender/draw/intern/draw_cache_impl_subdivision.cc
@@ -69,6 +69,7 @@ enum {
   SHADER_PATCH_EVALUATION,
   SHADER_PATCH_EVALUATION_FVAR,
   SHADER_PATCH_EVALUATION_FACE_DOTS,
+  SHADER_PATCH_EVALUATION_FACE_DOTS_WITH_NORMALS,
   SHADER_COMP_CUSTOM_DATA_INTERP_1D,
   SHADER_COMP_CUSTOM_DATA_INTERP_2D,
   SHADER_COMP_CUSTOM_DATA_INTERP_3D,
@@ -107,7 +108,8 @@ static const char *get_shader_code(int shader_type)
     }
     case SHADER_PATCH_EVALUATION:
     case SHADER_PATCH_EVALUATION_FVAR:
-    case SHADER_PATCH_EVALUATION_FACE_DOTS: {
+    case SHADER_PATCH_EVALUATION_FACE_DOTS:
+    case SHADER_PATCH_EVALUATION_FACE_DOTS_WITH_NORMALS: {
       return datatoc_common_subdiv_patch_evaluation_comp_glsl;
     }
     case SHADER_COMP_CUSTOM_DATA_INTERP_1D:
@@ -163,6 +165,9 @@ static const char *get_shader_name(int shader_type)
     case SHADER_PATCH_EVALUATION_FACE_DOTS: {
       return "subdiv patch evaluation face dots";
     }
+    case SHADER_PATCH_EVALUATION_FACE_DOTS_WITH_NORMALS: {
+      return "subdiv patch evaluation face dots with normals";
+    }
     case SHADER_COMP_CUSTOM_DATA_INTERP_1D: {
       return "subdiv custom data interp 1D";
     }
@@ -206,6 +211,13 @@ static GPUShader *get_patch_evaluation_shader(int shader_type)
           "#define OPENSUBDIV_GLSL_COMPUTE_USE_1ST_DERIVATIVES\n"
           "#define FDOTS_EVALUATION\n";
     }
+    else if (shader_type == SHADER_PATCH_EVALUATION_FACE_DOTS_WITH_NORMALS) {
+      defines =
+          "#define OSD_PATCH_BASIS_GLSL\n"
+          "#define OPENSUBDIV_GLSL_COMPUTE_USE_1ST_DERIVATIVES\n"
+          "#define FDOTS_EVALUATION\n"
+          "#define FOTS_NORMALS\n";
+    }
     else {
       defines =
           "#define OSD_PATCH_BASIS_GLSL\n"
@@ -1625,7 +1637,9 @@ void draw_subdiv_build_fdots_buffers(const DRWSubdivCache *cache,
                                                                get_patch_param_format());
   evaluator->wrapPatchParamBuffer(evaluator, &patch_param_buffer_interface);
 
-  GPUShader *shader = get_patch_evaluation_shader(SHADER_PATCH_EVALUATION_FACE_DOTS);
+  GPUShader *shader = get_patch_evaluation_shader(
+      fdots_nor ? SHADER_PATCH_EVALUATION_FACE_DOTS_WITH_NORMALS :
+                  SHADER_PATCH_EVALUATION_FACE_DOTS);
   GPU_shader_bind(shader);
 
   int binding_point = 0;
@@ -1638,7 +1652,11 @@ void draw_subdiv_build_fdots_buffers(const DRWSubdivCache *cache,
   GPU_vertbuf_bind_as_ssbo(patch_index_buffer, binding_point++);
   GPU_vertbuf_bind_as_ssbo(patch_param_buffer, binding_point++);
   GPU_vertbuf_bind_as_ssbo(fdots_pos, binding_point++);
-  GPU_vertbuf_bind_as_ssbo(fdots_nor, binding_point++);
+  /* F-dots normals may not be requested, still reserve the binding point. */
+  if (fdots_nor) {
+    GPU_vertbuf_bind_as_ssbo(fdots_nor, binding_point);
+  }
+  binding_point++;
   GPU_indexbuf_bind_as_ssbo(fdots_indices, binding_point++);
   GPU_vertbuf_bind_as_ssbo(cache->extra_coarse_face_data, binding_point++);
   BLI_assert(binding_point <= MAX_GPU_SUBDIV_SSBOS);
diff --git a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_fdots_pos.cc b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_fdots_pos.cc
index c2b4d389b7c..1671a1cd1e7 100644
--- a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_fdots_pos.cc
+++ b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_fdots_pos.cc
@@ -110,8 +110,11 @@ static void extract_fdots_init_subdiv(const DRWSubdivCache *subdiv_cache,
   GPUVertBuf *fdots_nor_vbo = cache->final.buff.vbo.fdots_nor;
   GPUIndexBuf *fdots_pos_ibo = cache->final.buff.ibo.fdots;
 
-  GPU_vertbuf_init_build_on_device(
-      fdots_nor_vbo, get_fdots_nor_format_subdiv(), subdiv_cache->num_coarse_poly);
+  /* The normals may not be requested. */
+  if (fdots_nor_vbo) {
+    GPU_vertbuf_init_build_on_device(
+        fdots_nor_vbo, get_fdots_nor_format_subdiv(), subdiv_cache->num_coarse_poly);
+  }
   GPU_vertbuf_init_build_on_device(
       fdots_pos_vbo, get_fdots_pos_format(), subdiv_cache->num_coarse_poly);
   GPU_indexbuf_init_build_on_device(fdots_pos_ibo, subdiv_cache->num_coarse_poly);
diff --git a/source/blender/draw/intern/shaders/common_subdiv_patch_evaluation_comp.glsl b/source/blender/draw/intern/shaders/common_subdiv_patch_evaluation_comp.glsl
index e8d98428a8d..e842a73b8b3 100644
--- a/source/blender/draw/intern/shaders/common_subdiv_patch_evaluation_comp.glsl
+++ b/source/blender/draw/intern/shaders/common_subdiv_patch_evaluation_comp.glsl
@@ -70,10 +70,12 @@ layout(std430, binding = 8) writeonly buffer outputVertices
   FDotVert output_verts[];
 };
 
+#  ifdef FDOTS_NORMALS
 layout(std430, binding = 9) writeonly buffer outputNormals
 {
   FDotNor output_nors[];
 };
+#  endif
 
 layout(std430, binding = 10) writeonly buffer outputFdotsIndices
 {
@@ -375,13 +377,15 @@ void main()
   fnor.flag = get_face_flag(coarse_quad_index);
 
   output_verts[coarse_quad_index] = vert;
+#  ifdef FDOTS_NORMALS
   output_nors[coarse_quad_index] = fnor;
+#  endif
 
   if (is_face_hidden(coarse_quad_index)) {
-      output_indices[coarse_quad_index] = 0xffffffff;
+    output_indices[coarse_quad_index] = 0xffffffff;
   }
   else {
-      output_indices[coarse_quad_index] = coarse_quad_index;
+    output_indices[coarse_quad_index] = coarse_quad_index;
   }
 }
 #else