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, 27 insertions, 0 deletions

diff --git a/source/blender/gpu/GPU_material.h b/source/blender/gpu/GPU_material.h
index 2f12625acac..67cd1a61aed 100644
--- a/source/blender/gpu/GPU_material.h
+++ b/source/blender/gpu/GPU_material.h
@@ -34,6 +34,7 @@
 extern "C" {
 #endif
 
+struct GHash;
 struct GPUMaterial;
 struct GPUNode;
 struct GPUNodeLink;
@@ -143,6 +144,7 @@ typedef void (*GPUMaterialEvalCallbackFn)(GPUMaterial *mat,
 GPUNodeLink *GPU_constant(const float *num);
 GPUNodeLink *GPU_uniform(const float *num);
 GPUNodeLink *GPU_attribute(GPUMaterial *mat, CustomDataType type, const char *name);
+GPUNodeLink *GPU_uniform_attribute(GPUMaterial *mat, const char *name, bool use_dupli);
 GPUNodeLink *GPU_image(GPUMaterial *mat,
                        struct Image *ima,
                        struct ImageUser *iuser,
@@ -259,6 +261,31 @@ ListBase GPU_material_attributes(GPUMaterial *material);
 ListBase GPU_material_textures(GPUMaterial *material);
 ListBase GPU_material_volume_grids(GPUMaterial *material);
 
+typedef struct GPUUniformAttr {
+  struct GPUUniformAttr *next, *prev;
+
+  /* Meaningful part of the attribute set key. */
+  char name[64]; /* MAX_CUSTOMDATA_LAYER_NAME */
+  bool use_dupli;
+
+  /* Helper fields used by code generation. */
+  short id;
+  int users;
+} GPUUniformAttr;
+
+typedef struct GPUUniformAttrList {
+  ListBase list; /* GPUUniformAttr */
+
+  /* List length and hash code precomputed for fast lookup and comparison. */
+  unsigned int count, hash_code;
+} GPUUniformAttrList;
+
+GPUUniformAttrList *GPU_material_uniform_attributes(GPUMaterial *material);
+
+struct GHash *GPU_uniform_attr_list_hash_new(const char *info);
+void GPU_uniform_attr_list_copy(GPUUniformAttrList *dest, GPUUniformAttrList *src);
+void GPU_uniform_attr_list_free(GPUUniformAttrList *set);
+
 #ifdef __cplusplus
 }
 #endif