DRW-Next: Add uniform attributes (object attributes) support

This replaces the direct shader uniform layout declaration by a linear
search through a global buffer.

Each instance has an attribute offset inside the global buffer and an
attribute count.

This removes any padding and tighly pack all uniform attributes inside
a single buffer.

This would also remove the limit of 8 attribute but it is kept because of
compatibility with the old system that is still used by the old draw
manager.

7 files changed, 208 insertions, 19 deletions

diff --git a/source/blender/draw/intern/draw_manager.cc b/source/blender/draw/intern/draw_manager.cc
index 8fb2ffb39e8..2841abb53e7 100644
--- a/source/blender/draw/intern/draw_manager.cc
+++ b/source/blender/draw/intern/draw_manager.cc
@@ -43,6 +43,7 @@ void Manager::begin_sync()
   memset(infos_buf.data(), 0xF0, resource_len_ * sizeof(*infos_buf.data()));
 #endif
   resource_len_ = 0;
+  attribute_len_ = 0;
   /* TODO(fclem): Resize buffers if too big, but with an hysteresis threshold. */
 
   object_active = DST.draw_ctx.obact;
@@ -58,6 +59,8 @@ void Manager::end_sync()
   matrix_buf.push_update();
   bounds_buf.push_update();
   infos_buf.push_update();
+  attributes_buf.push_update();
+  attributes_buf_legacy.push_update();
 
   debug_bind();
 
@@ -90,6 +93,16 @@ void Manager::debug_bind()
 #endif
 }
 
+void Manager::resource_bind()
+{
+  GPU_storagebuf_bind(matrix_buf, DRW_OBJ_MAT_SLOT);
+  GPU_storagebuf_bind(infos_buf, DRW_OBJ_INFOS_SLOT);
+  GPU_storagebuf_bind(attributes_buf, DRW_OBJ_ATTR_SLOT);
+  /* 2 is the hardcoded location of the uniform attr UBO. */
+  /* TODO(@fclem): Remove this workaround. */
+  GPU_uniformbuf_bind(attributes_buf_legacy, 2);
+}
+
 void Manager::submit(PassSimple &pass, View &view)
 {
   view.bind();
@@ -101,9 +114,7 @@ void Manager::submit(PassSimple &pass, View &view)
 
   pass.draw_commands_buf_.bind(state, pass.headers_, pass.commands_);
 
-  GPU_storagebuf_bind(matrix_buf, DRW_OBJ_MAT_SLOT);
-  GPU_storagebuf_bind(infos_buf, DRW_OBJ_INFOS_SLOT);
-  // GPU_storagebuf_bind(attribute_buf, DRW_OBJ_ATTR_SLOT); /* TODO */
+  resource_bind();
 
   pass.submit(state);
 
@@ -126,9 +137,7 @@ void Manager::submit(PassMain &pass, View &view)
 
   pass.draw_commands_buf_.bind(state, pass.headers_, pass.commands_, view.visibility_buf_);
 
-  GPU_storagebuf_bind(matrix_buf, DRW_OBJ_MAT_SLOT);
-  GPU_storagebuf_bind(infos_buf, DRW_OBJ_INFOS_SLOT);
-  // GPU_storagebuf_bind(attribute_buf, DRW_OBJ_ATTR_SLOT); /* TODO */
+  resource_bind();
 
   pass.submit(state);
 
@@ -150,9 +159,7 @@ void Manager::submit(PassSimple &pass)
 
   pass.draw_commands_buf_.bind(state, pass.headers_, pass.commands_);
 
-  GPU_storagebuf_bind(matrix_buf, DRW_OBJ_MAT_SLOT);
-  GPU_storagebuf_bind(infos_buf, DRW_OBJ_INFOS_SLOT);
-  // GPU_storagebuf_bind(attribute_buf, DRW_OBJ_ATTR_SLOT); /* TODO */
+  resource_bind();
 
   pass.submit(state);
 
diff --git a/source/blender/draw/intern/draw_manager.hh b/source/blender/draw/intern/draw_manager.hh
index 5f110b8bb6b..867b376702c 100644
--- a/source/blender/draw/intern/draw_manager.hh
+++ b/source/blender/draw/intern/draw_manager.hh
@@ -13,7 +13,9 @@
  * \note It is currently work in progress and should replace the old global draw manager.
  */
 
+#include "BLI_listbase_wrapper.hh"
 #include "BLI_sys_types.h"
+#include "GPU_material.h"
 
 #include "draw_resource.hh"
 #include "draw_view.hh"
@@ -41,6 +43,9 @@ class Manager {
   using ObjectMatricesBuf = StorageArrayBuffer<ObjectMatrices, 128>;
   using ObjectBoundsBuf = StorageArrayBuffer<ObjectBounds, 128>;
   using ObjectInfosBuf = StorageArrayBuffer<ObjectInfos, 128>;
+  using ObjectAttributeBuf = StorageArrayBuffer<ObjectAttribute, 128>;
+  /** TODO(fclem): Remove once we get rid of old EEVEE codebase. DRW_RESOURCE_CHUNK_LEN = 512 */
+  using ObjectAttributeLegacyBuf = UniformArrayBuffer<float4, 8 * 512>;
 
  public:
   struct SubmitDebugOutput {
@@ -67,14 +72,25 @@ class Manager {
   ObjectBoundsBuf bounds_buf;
   ObjectInfosBuf infos_buf;
 
+  /**
+   * Object Attributes are reference by indirection data inside ObjectInfos.
+   * This is because attribute list is arbitrary.
+   */
+  ObjectAttributeBuf attributes_buf;
+  /** TODO(fclem): Remove once we get rid of old EEVEE codebase. Only here to satisfy bindings. */
+  ObjectAttributeLegacyBuf attributes_buf_legacy;
+
   /** List of textures coming from Image data-blocks. They need to be refcounted in order to avoid
    * beeing freed in another thread. */
   Vector<GPUTexture *> acquired_textures;
 
  private:
+  /** Number of resource handle recorded. */
   uint resource_len_ = 0;
-  Object *object = nullptr;
+  /** Number of object attribute recorded. */
+  uint attribute_len_ = 0;
 
+  Object *object = nullptr;
   Object *object_active = nullptr;
 
  public:
@@ -104,7 +120,7 @@ class Manager {
    * Populate additional per resource data on demand.
    */
   void extract_object_attributes(ResourceHandle handle,
-                                 Object &object,
+                                 const ObjectRef &ref,
                                  Span<GPUMaterial *> materials);
 
   /**
@@ -145,6 +161,7 @@ class Manager {
   void end_sync();
 
   void debug_bind();
+  void resource_bind();
 };
 
 inline ResourceHandle Manager::resource_handle(const ObjectRef ref)
@@ -175,13 +192,34 @@ inline ResourceHandle Manager::resource_handle(const float4x4 &model_matrix,
 }
 
 inline void Manager::extract_object_attributes(ResourceHandle handle,
-                                               Object &object,
+                                               const ObjectRef &ref,
                                                Span<GPUMaterial *> materials)
 {
-  /* TODO */
-  (void)handle;
-  (void)object;
-  (void)materials;
+  ObjectInfos &infos = infos_buf.get_or_resize(handle.resource_index());
+  infos.object_attrs_offset = attribute_len_;
+
+  /* Simple cache solution to avoid duplicates. */
+  Vector<uint32_t, 4> hash_cache;
+
+  for (const GPUMaterial *mat : materials) {
+    const GPUUniformAttrList *attr_list = GPU_material_uniform_attributes(mat);
+    if (attr_list == nullptr) {
+      continue;
+    }
+
+    LISTBASE_FOREACH (const GPUUniformAttr *, attr, &attr_list->list) {
+      /** WATCH: Linear Search. Avoid duplicate attributes across materials. */
+      if ((mat != materials.first()) && (hash_cache.first_index_of_try(attr->hash_code) != -1)) {
+        /* Attribute has already been added to the attribute buffer by another material. */
+        continue;
+      }
+      hash_cache.append(attr->hash_code);
+      if (attributes_buf.get_or_resize(attribute_len_).sync(ref, *attr)) {
+        infos.object_attrs_len++;
+        attribute_len_++;
+      }
+    }
+  }
 }
 
 }  // namespace blender::draw
diff --git a/source/blender/draw/intern/draw_resource.cc b/source/blender/draw/intern/draw_resource.cc
new file mode 100644
index 00000000000..689df4edb31
--- /dev/null
+++ b/source/blender/draw/intern/draw_resource.cc
@@ -0,0 +1,109 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright 2022 Blender Foundation. */
+
+/** \file
+ * \ingroup draw
+ */
+
+#include "DNA_particle_types.h"
+#include "RNA_access.h"
+#include "RNA_path.h"
+#include "RNA_types.h"
+
+#include "draw_handle.hh"
+#include "draw_manager.hh"
+#include "draw_shader_shared.h"
+
+/* -------------------------------------------------------------------- */
+/** \name ObjectAttributes
+ * \{ */
+
+/**
+ * Extract object attribute from RNA property.
+ * Returns true if the attribute was correctly extracted.
+ * This function mirrors lookup_property in cycles/blender/blender_object.cpp
+ */
+bool ObjectAttribute::id_property_lookup(ID *id, const char *name)
+{
+  PointerRNA ptr, id_ptr;
+  PropertyRNA *prop;
+
+  if (id == nullptr) {
+    return false;
+  }
+
+  RNA_id_pointer_create(id, &id_ptr);
+
+  if (!RNA_path_resolve(&id_ptr, name, &ptr, &prop)) {
+    return false;
+  }
+
+  if (prop == nullptr) {
+    return false;
+  }
+
+  PropertyType type = RNA_property_type(prop);
+  int array_len = RNA_property_array_length(&ptr, prop);
+
+  if (array_len == 0) {
+    float value;
+
+    if (type == PROP_FLOAT) {
+      value = RNA_property_float_get(&ptr, prop);
+    }
+    else if (type == PROP_INT) {
+      value = RNA_property_int_get(&ptr, prop);
+    }
+    else {
+      return false;
+    }
+
+    *reinterpret_cast<float4 *>(&data_x) = float4(value, value, value, 1.0f);
+    return true;
+  }
+
+  if (type == PROP_FLOAT && array_len <= 4) {
+    *reinterpret_cast<float4 *>(&data_x) = float4(0.0f, 0.0f, 0.0f, 1.0f);
+    RNA_property_float_get_array(&ptr, prop, &data_x);
+    return true;
+  }
+  return false;
+}
+
+/**
+ * Go through all possible source of the given object uniform attribute.
+ * Returns true if the attribute was correctly filled.
+ * This function mirrors lookup_instance_property in cycles/blender/blender_object.cpp
+ */
+bool ObjectAttribute::sync(const blender::draw::ObjectRef &ref, const GPUUniformAttr &attr)
+{
+  hash_code = attr.hash_code;
+
+  /* If requesting instance data, check the parent particle system and object. */
+  if (attr.use_dupli) {
+    if ((ref.dupli_object != nullptr) && (ref.dupli_object->particle_system != nullptr)) {
+      ParticleSettings *settings = ref.dupli_object->particle_system->part;
+      if (this->id_property_lookup((ID *)settings, attr.name_id_prop) ||
+          this->id_property_lookup((ID *)settings, attr.name)) {
+        return true;
+      }
+    }
+    if (this->id_property_lookup((ID *)ref.dupli_parent, attr.name_id_prop) ||
+        this->id_property_lookup((ID *)ref.dupli_parent, attr.name)) {
+      return true;
+    }
+  }
+
+  /* Check the object and mesh. */
+  if (ref.object != nullptr) {
+    if (this->id_property_lookup((ID *)ref.object, attr.name_id_prop) ||
+        this->id_property_lookup((ID *)ref.object, attr.name) ||
+        this->id_property_lookup((ID *)ref.object->data, attr.name_id_prop) ||
+        this->id_property_lookup((ID *)ref.object->data, attr.name)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+/** \} */
diff --git a/source/blender/draw/intern/draw_resource.hh b/source/blender/draw/intern/draw_resource.hh
index 503833e8a6d..22ee43592a9 100644
--- a/source/blender/draw/intern/draw_resource.hh
+++ b/source/blender/draw/intern/draw_resource.hh
@@ -59,11 +59,17 @@ ENUM_OPERATORS(eObjectInfoFlag, OBJECT_NEGATIVE_SCALE)
 
 inline void ObjectInfos::sync()
 {
+  object_attrs_len = 0;
+  object_attrs_offset = 0;
+
   flag = eObjectInfoFlag::OBJECT_NO_INFO;
 }
 
 inline void ObjectInfos::sync(const blender::draw::ObjectRef ref, bool is_active_object)
 {
+  object_attrs_len = 0;
+  object_attrs_offset = 0;
+
   color = ref.object->color;
   index = ref.object->index;
   SET_FLAG_FROM_TEST(flag, is_active_object, eObjectInfoFlag::OBJECT_ACTIVE);
diff --git a/source/blender/draw/intern/draw_shader_shared.h b/source/blender/draw/intern/draw_shader_shared.h
index 00d54311548..d43bfe6b159 100644
--- a/source/blender/draw/intern/draw_shader_shared.h
+++ b/source/blender/draw/intern/draw_shader_shared.h
@@ -13,6 +13,7 @@ typedef struct ObjectInfos ObjectInfos;
 typedef struct ObjectBounds ObjectBounds;
 typedef struct VolumeInfos VolumeInfos;
 typedef struct CurvesInfos CurvesInfos;
+typedef struct ObjectAttribute ObjectAttribute;
 typedef struct DrawCommand DrawCommand;
 typedef struct DispatchCommand DispatchCommand;
 typedef struct DRWDebugPrintBuffer DRWDebugPrintBuffer;
@@ -22,6 +23,8 @@ typedef struct DRWDebugDrawBuffer DRWDebugDrawBuffer;
 #  ifdef __cplusplus
 /* C++ only forward declarations. */
 struct Object;
+struct ID;
+struct GPUUniformAttr;
 
 namespace blender::draw {
 
@@ -130,9 +133,9 @@ struct ObjectInfos {
 #else
   /** Uploaded as center + size. Converted to mul+bias to local coord.  */
   float3 orco_add;
-  float _pad0;
+  uint object_attrs_offset;
   float3 orco_mul;
-  float _pad1;
+  uint object_attrs_len;
 
   float4 color;
   uint index;
@@ -193,6 +196,23 @@ struct CurvesInfos {
 };
 BLI_STATIC_ASSERT_ALIGN(CurvesInfos, 16)
 
+#pragma pack(push, 4)
+struct ObjectAttribute {
+  /* Workaround the padding cost from alignment requirements.
+   * (see GL spec : 7.6.2.2 Standard Uniform Block Layout) */
+  float data_x, data_y, data_z, data_w;
+  uint hash_code;
+
+#if !defined(GPU_SHADER) && defined(__cplusplus)
+  bool sync(const blender::draw::ObjectRef &ref, const GPUUniformAttr &attr);
+  bool id_property_lookup(ID *id, const char *name);
+#endif
+};
+#pragma pack(pop)
+/** \note we only align to 4 bytes and fetch data manually so make sure
+ * C++ compiler gives us the same size. */
+BLI_STATIC_ASSERT_ALIGN(ObjectAttribute, 20)
+
 /** \} */
 
 /* -------------------------------------------------------------------- */
diff --git a/source/blender/draw/intern/shaders/common_attribute_lib.glsl b/source/blender/draw/intern/shaders/common_attribute_lib.glsl
index ce5e49c7f63..6b5b6fcc846 100644
--- a/source/blender/draw/intern/shaders/common_attribute_lib.glsl
+++ b/source/blender/draw/intern/shaders/common_attribute_lib.glsl
@@ -25,3 +25,4 @@ float attr_load_float(sampler3D tex);
 
 float attr_load_temperature_post(float attr);
 vec4 attr_load_color_post(vec4 attr);
+vec4 attr_load_uniform(vec4 attr, const uint attr_hash);
diff --git a/source/blender/draw/intern/shaders/draw_object_infos_info.hh b/source/blender/draw/intern/shaders/draw_object_infos_info.hh
index 2ec40ab76e3..31fee018fbc 100644
--- a/source/blender/draw/intern/shaders/draw_object_infos_info.hh
+++ b/source/blender/draw/intern/shaders/draw_object_infos_info.hh
@@ -25,4 +25,12 @@ GPU_SHADER_CREATE_INFO(draw_object_infos_new)
     .define("OrcoTexCoFactors", "(drw_infos[resource_id].orco_mul_bias)")
     .define("ObjectInfo", "(drw_infos[resource_id].infos)")
     .define("ObjectColor", "(drw_infos[resource_id].color)")
-    .storage_buf(DRW_OBJ_INFOS_SLOT, Qualifier::READ, "ObjectInfos", "drw_infos[]");
\ No newline at end of file
+    .storage_buf(DRW_OBJ_INFOS_SLOT, Qualifier::READ, "ObjectInfos", "drw_infos[]");
+
+/** \note Requires draw_object_infos_new. */
+GPU_SHADER_CREATE_INFO(draw_object_attribute_new)
+    .define("OBATTR_LIB")
+    .define("ObjectAttributeStart", "(drw_infos[resource_id].orco_mul_bias[0].w)")
+    .define("ObjectAttributeLen", "(drw_infos[resource_id].orco_mul_bias[1].w)")
+    .storage_buf(DRW_OBJ_ATTR_SLOT, Qualifier::READ, "ObjectAttribute", "drw_attrs[]")
+    .additional_info("draw_object_infos_new");