From 8f9599d17e80254928d2d72081a4c7e0dee64038 Mon Sep 17 00:00:00 2001
From: Jeroen Bakker <jbakker>
Date: Wed, 26 May 2021 17:02:32 +0200
Subject: DrawManager: Use Compute Shader to Update Hair.

This patch will use compute shaders to create the VBO for hair.
The previous implementation uses tranform feedback.

Timings master (transform feedback with GPU_USAGE_STATIC between 0.000069s and 0.000362s
Timings transform feedback with GPU_USAGE_DEVICE_ONLY. between 0.000057s and 0.000122s
Timings compute shader between 0.000032 and 0.000092s

Future improvements:
* Generate hair Index buffer using compute shaders: currently done single threaded on CPU, easy to add as compute shader.

Reviewed By: fclem

Differential Revision: https://developer.blender.org/D11057
---
 source/blender/draw/intern/draw_manager.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

(limited to 'source/blender/draw/intern/draw_manager.h')

diff --git a/source/blender/draw/intern/draw_manager.h b/source/blender/draw/intern/draw_manager.h
index 84bc0327aa2..d4e22c83798 100644
--- a/source/blender/draw/intern/draw_manager.h
+++ b/source/blender/draw/intern/draw_manager.h
@@ -187,6 +187,10 @@ typedef enum {
   DRW_CMD_DRAW_INSTANCE = 2,
   DRW_CMD_DRAW_INSTANCE_RANGE = 3,
   DRW_CMD_DRAW_PROCEDURAL = 4,
+
+  /* Compute Commands. */
+  DRW_CMD_COMPUTE = 8,
+
   /* Other Commands */
   DRW_CMD_CLEAR = 12,
   DRW_CMD_DRWSTATE = 13,
@@ -224,6 +228,12 @@ typedef struct DRWCommandDrawInstanceRange {
   uint inst_count;
 } DRWCommandDrawInstanceRange;
 
+typedef struct DRWCommandCompute {
+  int groups_x_len;
+  int groups_y_len;
+  int groups_z_len;
+} DRWCommandCompute;
+
 typedef struct DRWCommandDrawProcedural {
   GPUBatch *batch;
   DRWResourceHandle handle;
@@ -260,6 +270,7 @@ typedef union DRWCommand {
   DRWCommandDrawInstance instance;
   DRWCommandDrawInstanceRange instance_range;
   DRWCommandDrawProcedural procedural;
+  DRWCommandCompute compute;
   DRWCommandSetMutableState state;
   DRWCommandSetStencil stencil;
   DRWCommandSetSelectID select_id;
@@ -274,6 +285,7 @@ struct DRWCallBuffer {
 };
 
 /** Used by #DRWUniform.type */
+/* TODO(jbakker): rename to DRW_RESOURCE/DRWResourceType. */
 typedef enum {
   DRW_UNIFORM_INT = 0,
   DRW_UNIFORM_INT_COPY,
@@ -286,6 +298,7 @@ typedef enum {
   DRW_UNIFORM_BLOCK,
   DRW_UNIFORM_BLOCK_REF,
   DRW_UNIFORM_TFEEDBACK_TARGET,
+  DRW_UNIFORM_VERTEX_BUFFER_AS_STORAGE,
   /** Per drawcall uniforms/UBO */
   DRW_UNIFORM_BLOCK_OBMATS,
   DRW_UNIFORM_BLOCK_OBINFOS,
-- 
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