EEEVEE: Object Motion Blur: Initial Implementation

This adds object motion blur vectors for EEVEE as well as better noise
reduction for it.

For TAA reprojection we just compute the motion vector on the fly based on
camera motion and depth buffer. This makes possible to store another motion
vector only for the blurring which is not useful for TAA history fetching.

Motion Data is saved per object & per geometry if using deformation blur.
We support deformation motion blur by saving previous VBO and modifying the
actual GPUBatch for the geometry to include theses VBOs.

We store Previous and Next frame motion in the same motion vector buffer
(RG for prev and BA for next). This makes non linear motion blur (like
rotating objects) less prone to outward/inward blur.

We also improve the motion blur post process to expand outside the objects
border. We use a tile base approach and the max size of the blur is set via
a new render setting.

We use a background reconstruction method that needs another setting
(Background Separation).

Sampling is done using a fixed 8 dithered samples per direction. The final
render samples will clear the noise like other stochastic effects.

One caveat is that hair particles are not yet supported. Support will
come in another patch.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D7297

source/blender/gpu/GPU_vertex_buffer.h

@@ -80,6 +80,8 @@ void GPU_vertbuf_init_with_format_ex(GPUVertBuf *, const GPUVertFormat *, GPUUsa
 #define GPU_vertbuf_init_with_format(verts, format) \
   GPU_vertbuf_init_with_format_ex(verts, format, GPU_USAGE_STATIC)
 
+GPUVertBuf *GPU_vertbuf_duplicate(GPUVertBuf *verts);
+
 uint GPU_vertbuf_size_get(const GPUVertBuf *);
 void GPU_vertbuf_data_alloc(GPUVertBuf *, uint v_len);
 void GPU_vertbuf_data_resize(GPUVertBuf *, uint v_len);

source/blender/gpu/GPU_vertex_format.h

@@ -124,6 +124,10 @@ BLI_INLINE const char *GPU_vertformat_attr_name_get(const GPUVertFormat *format,
   return format->names + attr->names[n_idx];
 }
 
+/* WARNING: Can only rename using a string with same character count.
+ * WARNING: This removes all other aliases of this attrib */
+void GPU_vertformat_attr_rename(GPUVertFormat *format, int attr, const char *new_name);
+
 void GPU_vertformat_safe_attr_name(const char *attr_name, char *r_safe_name, uint max_len);
 
 /* format conversion */

source/blender/gpu/intern/gpu_vertex_buffer.c

@@ -85,6 +85,35 @@ void GPU_vertbuf_init_with_format_ex(GPUVertBuf *verts,
   }
 }
 
+GPUVertBuf *GPU_vertbuf_duplicate(GPUVertBuf *verts)
+{
+  GPUVertBuf *verts_dst = GPU_vertbuf_create(GPU_USAGE_STATIC);
+  /* Full copy. */
+  *verts_dst = *verts;
+  GPU_vertformat_copy(&verts_dst->format, &verts->format);
+
+  if (verts->vbo_id) {
+    uint buffer_sz = GPU_vertbuf_size_get(verts);
+
+    verts_dst->vbo_id = GPU_buf_alloc();
+
+    glBindBuffer(GL_COPY_READ_BUFFER, verts->vbo_id);
+    glBindBuffer(GL_COPY_WRITE_BUFFER, verts_dst->vbo_id);
+
+    glBufferData(GL_COPY_WRITE_BUFFER, buffer_sz, NULL, convert_usage_type_to_gl(verts->usage));
+
+    glCopyBufferSubData(GL_COPY_READ_BUFFER, GL_COPY_WRITE_BUFFER, 0, 0, buffer_sz);
+#if VRAM_USAGE
+    vbo_memory_usage += GPU_vertbuf_size_get(verts);
+#endif
+  }
+
+  if (verts->data) {
+    verts_dst->data = MEM_dupallocN(verts->data);
+  }
+  return verts_dst;
+}
+
 /** Same as discard but does not free. */
 void GPU_vertbuf_clear(GPUVertBuf *verts)
 {

source/blender/gpu/intern/gpu_vertex_format.c

@@ -262,6 +262,20 @@ int GPU_vertformat_attr_id_get(const GPUVertFormat *format, const char *name)
   return -1;
 }
 
+void GPU_vertformat_attr_rename(GPUVertFormat *format, int attr_id, const char *new_name)
+{
+  BLI_assert(attr_id > -1 && attr_id < format->attr_len);
+  GPUVertAttr *attr = &format->attrs[attr_id];
+  char *attr_name = (char *)GPU_vertformat_attr_name_get(format, attr, 0);
+  BLI_assert(strlen(attr_name) == strlen(new_name));
+  int i = 0;
+  while (attr_name[i] != '\0') {
+    attr_name[i] = new_name[i];
+    i++;
+  }
+  attr->name_len = 1;
+}
+
 /* Encode 8 original bytes into 11 safe bytes. */
 static void safe_bytes(char out[11], const char data[8])
 {