DRW: Instance selection id: use Batch buffers instead of DRWInstanceData

This is motivated by the refactor of DRWInstanceData to be actual non
contiguous mempools.

3 files changed, 37 insertions, 7 deletions

diff --git a/source/blender/draw/intern/draw_manager.h b/source/blender/draw/intern/draw_manager.h
index 6fd000c0939..77bb37b9c8a 100644
--- a/source/blender/draw/intern/draw_manager.h
+++ b/source/blender/draw/intern/draw_manager.h
@@ -253,7 +253,7 @@ struct DRWShadingGroup {
 #endif
 
 #ifdef USE_GPU_SELECT
-	DRWInstanceData *inst_selectid;
+	Gwn_VertBuf *inst_selectid;
 	DRWPass *pass_parent; /* backlink to pass we're in */
 	int override_selectid; /* Override for single object instances. */
 #endif
diff --git a/source/blender/draw/intern/draw_manager_data.c b/source/blender/draw/intern/draw_manager_data.c
index 105eab5a958..c5d7f205687 100644
--- a/source/blender/draw/intern/draw_manager_data.c
+++ b/source/blender/draw/intern/draw_manager_data.c
@@ -517,12 +517,10 @@ void DRW_shgroup_call_dynamic_add_array(DRWShadingGroup *shgroup, const void *at
 {
 #ifdef USE_GPU_SELECT
 	if (G.f & G_PICKSEL) {
-		if (shgroup->inst_selectid == NULL) {
-			shgroup->inst_selectid = DRW_instance_data_request(DST.idatalist, 1, 128);
+		if (shgroup->instance_count == shgroup->inst_selectid->vertex_ct) {
+			GWN_vertbuf_data_resize(shgroup->inst_selectid, shgroup->instance_count + 32);
 		}
-
-		int *select_id = DRW_instance_data_next(shgroup->inst_selectid);
-		*select_id = DST.select_id;
+		GWN_vertbuf_attr_set(shgroup->inst_selectid, 0, shgroup->instance_count, &DST.select_id);
 	}
 #endif
 
@@ -622,6 +620,21 @@ static void drw_shgroup_instance_init(
 
 	DRW_instancing_buffer_request(DST.idatalist, format, batch, shgroup,
 	                              &shgroup->instance_geom, &shgroup->instance_vbo);
+
+#ifdef USE_GPU_SELECT
+	if (G.f & G_PICKSEL) {
+		/* Not actually used for rendering but alloced in one chunk.
+		 * Plus we don't have to care about ownership. */
+		static Gwn_VertFormat inst_select_format = {0};
+		if (inst_select_format.attrib_ct == 0) {
+			GWN_vertformat_attr_add(&inst_select_format, "selectId", GWN_COMP_I32, 1, GWN_FETCH_INT);
+		}
+		Gwn_Batch *batch_dummy; /* Not used */
+		DRW_batching_buffer_request(DST.idatalist, &inst_select_format,
+		                            GWN_PRIM_POINTS, shgroup,
+		                            &batch_dummy, &shgroup->inst_selectid);
+	}
+#endif
 }
 
 static void drw_shgroup_batching_init(
@@ -644,6 +657,20 @@ static void drw_shgroup_batching_init(
 
 	DRW_batching_buffer_request(DST.idatalist, format, type, shgroup,
 	                            &shgroup->batch_geom, &shgroup->batch_vbo);
+
+#ifdef USE_GPU_SELECT
+	if (G.f & G_PICKSEL) {
+		/* Not actually used for rendering but alloced in one chunk. */
+		static Gwn_VertFormat inst_select_format = {0};
+		if (inst_select_format.attrib_ct == 0) {
+			GWN_vertformat_attr_add(&inst_select_format, "selectId", GWN_COMP_I32, 1, GWN_FETCH_INT);
+		}
+		Gwn_Batch *batch; /* Not used */
+		DRW_batching_buffer_request(DST.idatalist, &inst_select_format,
+		                            GWN_PRIM_POINTS, shgroup,
+		                            &batch, &shgroup->inst_selectid);
+	}
+#endif
 }
 
 static DRWShadingGroup *drw_shgroup_create_ex(struct GPUShader *shader, DRWPass *pass)
diff --git a/source/blender/draw/intern/draw_manager_exec.c b/source/blender/draw/intern/draw_manager_exec.c
index 8b0bbb3ad15..98135a614d9 100644
--- a/source/blender/draw/intern/draw_manager_exec.c
+++ b/source/blender/draw/intern/draw_manager_exec.c
@@ -1045,7 +1045,10 @@ static void draw_shgroup(DRWShadingGroup *shgroup, DRWState pass_state)
 	int *select_id = NULL;                                           \
 	if (G.f & G_PICKSEL) {                                           \
 		if (_shgroup->override_selectid == -1) {                        \
-			select_id = DRW_instance_data_get(_shgroup->inst_selectid); \
+			/* Hack : get vbo data without actually drawing. */     \
+			Gwn_VertBufRaw raw;                   \
+			GWN_vertbuf_attr_get_raw_data(_shgroup->inst_selectid, 0, &raw); \
+			select_id = GWN_vertbuf_raw_step(&raw);                               \
 			switch (_shgroup->type) {                                             \
 				case DRW_SHG_TRIANGLE_BATCH: _count = 3; break;                   \
 				case DRW_SHG_LINE_BATCH: _count = 2; break;                       \