DRW: Add DRW_shgroup_call_procedural_triangles_indirect

Just like the name suggest, this adds a way to draw a series of proceduraly
positioned triangles using and indirect buffer.

5 files changed, 97 insertions, 2 deletions

diff --git a/source/blender/draw/intern/DRW_render.h b/source/blender/draw/intern/DRW_render.h
index c2d26badc4c..701b395e0d7 100644
--- a/source/blender/draw/intern/DRW_render.h
+++ b/source/blender/draw/intern/DRW_render.h
@@ -454,6 +454,9 @@ void DRW_shgroup_call_compute_indirect(DRWShadingGroup *shgroup, GPUStorageBuf *
 void DRW_shgroup_call_procedural_points(DRWShadingGroup *sh, Object *ob, uint point_count);
 void DRW_shgroup_call_procedural_lines(DRWShadingGroup *sh, Object *ob, uint line_count);
 void DRW_shgroup_call_procedural_triangles(DRWShadingGroup *sh, Object *ob, uint tri_count);
+void DRW_shgroup_call_procedural_triangles_indirect(DRWShadingGroup *shgroup,
+                                                    Object *ob,
+                                                    GPUStorageBuf *indirect_buf);
 /**
  * \warning Only use with Shaders that have `IN_PLACE_INSTANCES` defined.
  * TODO: Should be removed.
diff --git a/source/blender/draw/intern/draw_manager.h b/source/blender/draw/intern/draw_manager.h
index 419b13edf1f..9e28169dcc4 100644
--- a/source/blender/draw/intern/draw_manager.h
+++ b/source/blender/draw/intern/draw_manager.h
@@ -188,6 +188,7 @@ typedef enum {
   DRW_CMD_DRAW_INSTANCE = 2,
   DRW_CMD_DRAW_INSTANCE_RANGE = 3,
   DRW_CMD_DRAW_PROCEDURAL = 4,
+  DRW_CMD_DRAW_INDIRECT = 5,
 
   /* Compute Commands. */
   DRW_CMD_COMPUTE = 8,
@@ -203,7 +204,7 @@ typedef enum {
   /* Needs to fit in 4bits */
 } eDRWCommandType;
 
-#define DRW_MAX_DRAW_CMD_TYPE DRW_CMD_DRAW_PROCEDURAL
+#define DRW_MAX_DRAW_CMD_TYPE DRW_CMD_DRAW_INDIRECT
 
 typedef struct DRWCommandDraw {
   GPUBatch *batch;
@@ -232,6 +233,12 @@ typedef struct DRWCommandDrawInstanceRange {
   uint inst_count;
 } DRWCommandDrawInstanceRange;
 
+typedef struct DRWCommandDrawIndirect {
+  GPUBatch *batch;
+  DRWResourceHandle handle;
+  GPUStorageBuf *indirect_buf;
+} DRWCommandDrawIndirect;
+
 typedef struct DRWCommandCompute {
   int groups_x_len;
   int groups_y_len;
@@ -286,6 +293,7 @@ typedef union DRWCommand {
   DRWCommandDrawInstance instance;
   DRWCommandDrawInstanceRange instance_range;
   DRWCommandDrawProcedural procedural;
+  DRWCommandDrawIndirect draw_indirect;
   DRWCommandCompute compute;
   DRWCommandComputeRef compute_ref;
   DRWCommandComputeIndirect compute_indirect;
diff --git a/source/blender/draw/intern/draw_manager_data.c b/source/blender/draw/intern/draw_manager_data.c
index 188d9114cd7..0535273d144 100644
--- a/source/blender/draw/intern/draw_manager_data.c
+++ b/source/blender/draw/intern/draw_manager_data.c
@@ -878,6 +878,17 @@ static void drw_command_draw_procedural(DRWShadingGroup *shgroup,
   cmd->vert_count = vert_count;
 }
 
+static void drw_command_draw_indirect(DRWShadingGroup *shgroup,
+                                      GPUBatch *batch,
+                                      DRWResourceHandle handle,
+                                      GPUStorageBuf *indirect_buf)
+{
+  DRWCommandDrawIndirect *cmd = drw_command_create(shgroup, DRW_CMD_DRAW_INDIRECT);
+  cmd->batch = batch;
+  cmd->handle = handle;
+  cmd->indirect_buf = indirect_buf;
+}
+
 static void drw_command_set_select_id(DRWShadingGroup *shgroup, GPUVertBuf *buf, uint select_id)
 {
   /* Only one can be valid. */
@@ -1005,6 +1016,7 @@ void DRW_shgroup_call_compute_indirect(DRWShadingGroup *shgroup, GPUStorageBuf *
 
   drw_command_compute_indirect(shgroup, indirect_buf);
 }
+
 void DRW_shgroup_barrier(DRWShadingGroup *shgroup, eGPUBarrier type)
 {
   BLI_assert(GPU_compute_shader_support());
@@ -1044,6 +1056,18 @@ void DRW_shgroup_call_procedural_triangles(DRWShadingGroup *shgroup, Object *ob,
   drw_shgroup_call_procedural_add_ex(shgroup, geom, ob, tri_count * 3);
 }
 
+void DRW_shgroup_call_procedural_triangles_indirect(DRWShadingGroup *shgroup,
+                                                    Object *ob,
+                                                    GPUStorageBuf *indirect_buf)
+{
+  struct GPUBatch *geom = drw_cache_procedural_triangles_get();
+  if (G.f & G_FLAG_PICKSEL) {
+    drw_command_set_select_id(shgroup, NULL, DST.select_id);
+  }
+  DRWResourceHandle handle = drw_resource_handle(shgroup, ob ? ob->obmat : NULL, ob);
+  drw_command_draw_indirect(shgroup, geom, handle, indirect_buf);
+}
+
 void DRW_shgroup_call_instances(DRWShadingGroup *shgroup,
                                 Object *ob,
                                 struct GPUBatch *geom,
diff --git a/source/blender/draw/intern/draw_manager_exec.c b/source/blender/draw/intern/draw_manager_exec.c
index e7e0e0ce41f..03c68ee532f 100644
--- a/source/blender/draw/intern/draw_manager_exec.c
+++ b/source/blender/draw/intern/draw_manager_exec.c
@@ -874,6 +874,25 @@ static void draw_call_single_do(DRWShadingGroup *shgroup,
                         state->baseinst_loc);
 }
 
+/* Not to be mistaken with draw_indirect_call which does batch many drawcalls together. This one
+ * only execute an indirect drawcall with user indirect buffer. */
+static void draw_call_indirect(DRWShadingGroup *shgroup,
+                               DRWCommandsState *state,
+                               GPUBatch *batch,
+                               DRWResourceHandle handle,
+                               GPUStorageBuf *indirect_buf)
+{
+  draw_call_batching_flush(shgroup, state);
+  draw_call_resource_bind(state, &handle);
+
+  if (G.f & G_FLAG_PICKSEL) {
+    GPU_select_load_id(state->select_id);
+  }
+
+  GPU_batch_set_shader(batch, shgroup->shader);
+  GPU_batch_draw_indirect(batch, indirect_buf);
+}
+
 static void draw_call_batching_start(DRWCommandsState *state)
 {
   state->neg_scale = false;
@@ -996,12 +1015,13 @@ static void draw_shgroup(DRWShadingGroup *shgroup, DRWState pass_state)
     while ((cmd = draw_command_iter_step(&iter, &cmd_type))) {
 
       switch (cmd_type) {
+        case DRW_CMD_DRAW_PROCEDURAL:
         case DRW_CMD_DRWSTATE:
         case DRW_CMD_STENCIL:
           draw_call_batching_flush(shgroup, &state);
           break;
         case DRW_CMD_DRAW:
-        case DRW_CMD_DRAW_PROCEDURAL:
+        case DRW_CMD_DRAW_INDIRECT:
         case DRW_CMD_DRAW_INSTANCE:
           if (draw_call_is_culled(&cmd->instance.handle, DST.view_active)) {
             continue;
@@ -1055,6 +1075,13 @@ static void draw_shgroup(DRWShadingGroup *shgroup, DRWState pass_state)
                               1,
                               true);
           break;
+        case DRW_CMD_DRAW_INDIRECT:
+          draw_call_indirect(shgroup,
+                             &state,
+                             cmd->draw_indirect.batch,
+                             cmd->draw_indirect.handle,
+                             cmd->draw_indirect.indirect_buf);
+          break;
         case DRW_CMD_DRAW_INSTANCE:
           draw_call_single_do(shgroup,
                               &state,
diff --git a/source/blender/draw/intern/draw_shader_shared.h b/source/blender/draw/intern/draw_shader_shared.h
index 266db22a84f..fbcc78e52f9 100644
--- a/source/blender/draw/intern/draw_shader_shared.h
+++ b/source/blender/draw/intern/draw_shader_shared.h
@@ -11,6 +11,9 @@ typedef struct ObjectMatrices ObjectMatrices;
 typedef struct ObjectInfos ObjectInfos;
 typedef struct VolumeInfos VolumeInfos;
 typedef struct CurvesInfos CurvesInfos;
+typedef struct DrawCommand DrawCommand;
+typedef struct DrawCommandIndexed DrawCommandIndexed;
+typedef struct DispatchCommand DispatchCommand;
 #endif
 
 #define DRW_SHADER_SHARED_H
@@ -98,3 +101,33 @@ BLI_STATIC_ASSERT_ALIGN(CurvesInfos, 16)
 #define OrcoTexCoFactors (drw_infos[resource_id].drw_OrcoTexCoFactors)
 #define ObjectInfo (drw_infos[resource_id].drw_Infos)
 #define ObjectColor (drw_infos[resource_id].drw_ObjectColor)
+
+/* Indirect commands structures. */
+
+struct DrawCommand {
+  uint v_count;
+  uint i_count;
+  uint v_first;
+  uint i_first;
+};
+BLI_STATIC_ASSERT_ALIGN(DrawCommand, 16)
+
+struct DrawCommandIndexed {
+  uint v_count;
+  uint i_count;
+  uint v_first;
+  uint base_index;
+  uint i_first;
+  uint _pad0;
+  uint _pad1;
+  uint _pad2;
+};
+BLI_STATIC_ASSERT_ALIGN(DrawCommandIndexed, 16)
+
+struct DispatchCommand {
+  uint num_groups_x;
+  uint num_groups_y;
+  uint num_groups_z;
+  uint _pad0;
+};
+BLI_STATIC_ASSERT_ALIGN(DispatchCommand, 16)