Materials: add custom object properties as uniform attributes.

This patch allows the user to type a property name into the
Attribute node, which will then output the value of the property
for each individual object, allowing to e.g. customize shaders
by object without duplicating the shader.

In order to make supporting this easier for Eevee, it is necessary
to explicitly choose whether the attribute is varying or uniform
via a dropdown option of the Attribute node. The dropdown also
allows choosing whether instancing should be taken into account.

The Cycles design treats all attributes as one common namespace,
so the Blender interface converts the enum to a name prefix that
can't be entered using keyboard.

In Eevee, the attributes are provided to the shader via a UBO indexed
with resource_id, similar to the existing Object Info data. Unlike it,
however, it is necessary to maintain a separate buffer for every
requested combination of attributes.

This is done using a hash table with the attribute set as the key,
as it is expected that technically different but similar materials
may use the same set of attributes. In addition, in order to minimize
wasted memory, a sparse UBO pool is implemented, so that chunks that
don't contain any data don't have to be allocated.

The back-end Cycles code is already refactored and committed by Brecht.

Differential Revision: https://developer.blender.org/D2057

1 files changed, 22 insertions, 0 deletions

diff --git a/source/blender/draw/intern/draw_instance_data.h b/source/blender/draw/intern/draw_instance_data.h
index e562d99097e..c959a9e19d6 100644
--- a/source/blender/draw/intern/draw_instance_data.h
+++ b/source/blender/draw/intern/draw_instance_data.h
@@ -31,8 +31,12 @@
 
 #define DRW_BUFFER_VERTS_CHUNK 128
 
+struct GHash;
+struct GPUUniformAttrList;
+
 typedef struct DRWInstanceData DRWInstanceData;
 typedef struct DRWInstanceDataList DRWInstanceDataList;
+typedef struct DRWSparseUniformBuf DRWSparseUniformBuf;
 
 void *DRW_instance_data_next(DRWInstanceData *idata);
 DRWInstanceData *DRW_instance_data_request(DRWInstanceDataList *idatalist, uint attr_size);
@@ -54,3 +58,21 @@ void DRW_instance_buffer_finish(DRWInstanceDataList *idatalist);
 void DRW_instance_data_list_reset(DRWInstanceDataList *idatalist);
 void DRW_instance_data_list_free_unused(DRWInstanceDataList *idatalist);
 void DRW_instance_data_list_resize(DRWInstanceDataList *idatalist);
+
+/* Sparse chunked UBO manager. */
+DRWSparseUniformBuf *DRW_sparse_uniform_buffer_new(unsigned int item_size,
+                                                   unsigned int chunk_size);
+void DRW_sparse_uniform_buffer_flush(DRWSparseUniformBuf *buffer);
+void DRW_sparse_uniform_buffer_clear(DRWSparseUniformBuf *buffer, bool free_all);
+void DRW_sparse_uniform_buffer_free(DRWSparseUniformBuf *buffer);
+bool DRW_sparse_uniform_buffer_is_empty(DRWSparseUniformBuf *buffer);
+void DRW_sparse_uniform_buffer_bind(DRWSparseUniformBuf *buffer, int chunk, int location);
+void DRW_sparse_uniform_buffer_unbind(DRWSparseUniformBuf *buffer, int chunk);
+void *DRW_sparse_uniform_buffer_ensure_item(DRWSparseUniformBuf *buffer, int chunk, int item);
+
+/* Uniform attribute UBO management. */
+struct GHash *DRW_uniform_attrs_pool_new(void);
+void DRW_uniform_attrs_pool_flush_all(struct GHash *table);
+void DRW_uniform_attrs_pool_clear_all(struct GHash *table);
+struct DRWSparseUniformBuf *DRW_uniform_attrs_pool_find_ubo(struct GHash *table,
+                                                            struct GPUUniformAttrList *key);