DRW: Add DRW_CALL_PROCEDURAL DRWCall type.

This mimics the behaviour of DRW_shgroup_empty_tri_batch_create and will
replace it eventually.

The advantage is that it's compatible with transform feedback.

4 files changed, 46 insertions, 0 deletions

diff --git a/source/blender/draw/intern/DRW_render.h b/source/blender/draw/intern/DRW_render.h
index 2b2a5bd3b48..e96594de590 100644
--- a/source/blender/draw/intern/DRW_render.h
+++ b/source/blender/draw/intern/DRW_render.h
@@ -329,6 +329,7 @@ DRWShadingGroup *DRW_shgroup_empty_tri_batch_create(
 DRWShadingGroup *DRW_shgroup_transform_feedback_create(
         struct GPUShader *shader, DRWPass *pass, struct Gwn_VertBuf *tf_target);
 
+
 typedef void (DRWCallGenerateFn)(
         DRWShadingGroup *shgroup,
         void (*draw_fn)(DRWShadingGroup *shgroup, struct Gwn_Batch *geom),
@@ -344,6 +345,9 @@ void DRW_shgroup_instance_batch(DRWShadingGroup *shgroup, struct Gwn_Batch *batc
 void DRW_shgroup_free(struct DRWShadingGroup *shgroup);
 void DRW_shgroup_call_add(DRWShadingGroup *shgroup, struct Gwn_Batch *geom, float (*obmat)[4]);
 void DRW_shgroup_call_object_add(DRWShadingGroup *shgroup, struct Gwn_Batch *geom, struct Object *ob);
+void DRW_shgroup_call_procedural_points_add(DRWShadingGroup *shgroup, unsigned int point_count, float (*obmat)[4]);
+void DRW_shgroup_call_procedural_lines_add(DRWShadingGroup *shgroup, unsigned int line_count, float (*obmat)[4]);
+void DRW_shgroup_call_procedural_triangles_add(DRWShadingGroup *shgroup, unsigned int tria_count, float (*obmat)[4]);
 void DRW_shgroup_call_object_add_with_callback(
         DRWShadingGroup *shgroup, struct Gwn_Batch *geom, struct Object *ob,
         DRWCallVisibilityFn *callback, void *user_data);
diff --git a/source/blender/draw/intern/draw_manager.h b/source/blender/draw/intern/draw_manager.h
index 267826d2d9a..f2b941810a7 100644
--- a/source/blender/draw/intern/draw_manager.h
+++ b/source/blender/draw/intern/draw_manager.h
@@ -127,6 +127,7 @@ typedef enum {
 	DRW_CALL_SINGLE,                 /* A single batch */
 	DRW_CALL_INSTANCES,              /* Draw instances without any instancing attribs. */
 	DRW_CALL_GENERATE,               /* Uses a callback to draw with any number of batches. */
+	DRW_CALL_PROCEDURAL,             /* Generate a drawcall without any Gwn_Batch. */
 } DRWCallType;
 
 typedef struct DRWCall {
@@ -146,6 +147,10 @@ typedef struct DRWCall {
 			DRWCallGenerateFn *geometry_fn;
 			void *user_data;
 		} generate;
+		struct { /* type == DRW_CALL_PROCEDURAL */
+			unsigned int prim_count;
+			Gwn_PrimType prim_type;
+		} procedural;
 	};
 
 	DRWCallType type;
diff --git a/source/blender/draw/intern/draw_manager_data.c b/source/blender/draw/intern/draw_manager_data.c
index b4dce47413e..2bf0d6a6b0e 100644
--- a/source/blender/draw/intern/draw_manager_data.c
+++ b/source/blender/draw/intern/draw_manager_data.c
@@ -366,6 +366,39 @@ void DRW_shgroup_call_add(DRWShadingGroup *shgroup, Gwn_Batch *geom, float (*obm
 	BLI_LINKS_APPEND(&shgroup->calls, call);
 }
 
+static void drw_shgroup_call_procedural_add_ex(
+        DRWShadingGroup *shgroup, Gwn_PrimType prim_type, unsigned int prim_count, float (*obmat)[4])
+{
+	BLI_assert(ELEM(shgroup->type, DRW_SHG_NORMAL, DRW_SHG_FEEDBACK_TRANSFORM));
+
+	DRWCall *call = BLI_mempool_alloc(DST.vmempool->calls);
+	call->state = drw_call_state_create(shgroup, obmat, NULL);
+	call->type = DRW_CALL_PROCEDURAL;
+	call->procedural.prim_type = prim_type;
+	call->procedural.prim_count = prim_count;
+#ifdef USE_GPU_SELECT
+	call->select_id = DST.select_id;
+#endif
+
+	BLI_LINKS_APPEND(&shgroup->calls, call);
+}
+
+void DRW_shgroup_call_procedural_points_add(DRWShadingGroup *shgroup, unsigned int point_count, float (*obmat)[4])
+{
+	drw_shgroup_call_procedural_add_ex(shgroup, GWN_PRIM_POINTS, point_count, obmat);
+}
+
+void DRW_shgroup_call_procedural_lines_add(DRWShadingGroup *shgroup, unsigned int line_count, float (*obmat)[4])
+{
+	drw_shgroup_call_procedural_add_ex(shgroup, GWN_PRIM_LINES, line_count, obmat);
+}
+
+void DRW_shgroup_call_procedural_triangles_add(DRWShadingGroup *shgroup, unsigned int tria_count, float (*obmat)[4])
+{
+	drw_shgroup_call_procedural_add_ex(shgroup, GWN_PRIM_TRIS, tria_count, obmat);
+}
+
+
 /* These calls can be culled and are optimized for redraw */
 void DRW_shgroup_call_object_add(DRWShadingGroup *shgroup, Gwn_Batch *geom, Object *ob)
 {
diff --git a/source/blender/draw/intern/draw_manager_exec.c b/source/blender/draw/intern/draw_manager_exec.c
index 110691373ab..8f5dce87c2b 100644
--- a/source/blender/draw/intern/draw_manager_exec.c
+++ b/source/blender/draw/intern/draw_manager_exec.c
@@ -820,6 +820,7 @@ static void draw_geometry_execute_ex(
         DRWShadingGroup *shgroup, Gwn_Batch *geom, uint start, uint count, bool draw_instance)
 {
 	/* Special case: empty drawcall, placement is done via shader, don't bind anything. */
+	/* TODO use DRW_CALL_PROCEDURAL instead */
 	if (geom == NULL) {
 		BLI_assert(shgroup->type == DRW_SHG_TRIANGLE_BATCH); /* Add other type if needed. */
 		/* Shader is already bound. */
@@ -1147,6 +1148,9 @@ static void draw_shgroup(DRWShadingGroup *shgroup, DRWState pass_state)
 				case DRW_CALL_GENERATE:
 					call->generate.geometry_fn(shgroup, draw_geometry_execute, call->generate.user_data);
 					break;
+				case DRW_CALL_PROCEDURAL:
+					GWN_draw_primitive(call->procedural.prim_type, call->procedural.prim_count);
+					break;
 				default:
 					BLI_assert(0);
 			}