From 3969e30c6f8c6790a070fc4e428f887faee875f6 Mon Sep 17 00:00:00 2001
From: Jeroen Bakker <jeroen@blender.org>
Date: Fri, 21 Feb 2025 10:21:44 +0100
Subject: [PATCH] SubDiv: Add base for polygon offset

Subdiv shader library contains an optional part that shaders can include.
As we are migrating each shader at a time there are now multiple PRs doing
the same thing. Best to add the changes to main already so it doesn't add
confusion during review.

Pull Request: https://projects.blender.org/blender/blender/pulls/134906
---
 source/blender/draw/CMakeLists.txt                 | 2 ++
 source/blender/draw/intern/draw_shader.cc          | 3 ---
 source/blender/draw/intern/draw_subdiv_defines.hh  | 2 ++
 source/blender/draw/intern/shaders/subdiv_info.hh  | 6 ++++++
 source/blender/draw/intern/shaders/subdiv_lib.glsl | 6 ++++++
 5 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/source/blender/draw/CMakeLists.txt b/source/blender/draw/CMakeLists.txt
index 2adf0b35724..41b1f901df2 100644
--- a/source/blender/draw/CMakeLists.txt
+++ b/source/blender/draw/CMakeLists.txt
@@ -187,6 +187,8 @@ set(SRC
   intern/draw_view.hh
   intern/draw_view_c.hh
   intern/draw_view_data.hh
+  intern/draw_subdiv_defines.hh
+  intern/draw_subdiv_shader_shared.hh
   intern/mesh_extractors/extract_mesh.hh
   engines/compositor/compositor_engine.h
   engines/eevee_next/eevee_ambient_occlusion.hh
diff --git a/source/blender/draw/intern/draw_shader.cc b/source/blender/draw/intern/draw_shader.cc
index 8bf71310e6d..a2bf4e83658 100644
--- a/source/blender/draw/intern/draw_shader.cc
+++ b/source/blender/draw/intern/draw_shader.cc
@@ -361,9 +361,6 @@ GPUShader *DRW_shader_subdiv_get(SubdivShaderType shader_type)
         defines = "#define GPU_AMD_DRIVER_BYTE_BUG\n";
       }
     }
-    else if (shader_type == SubdivShaderType::BUFFER_CUSTOM_NORMALS_FINALIZE) {
-      defines = "#define CUSTOM_NORMALS\n";
-    }
 
     e_data.subdiv_sh[uint(shader_type)] = GPU_shader_create_compute(
         compute_code, datatoc_subdiv_lib_glsl, defines, get_subdiv_shader_name(shader_type));
diff --git a/source/blender/draw/intern/draw_subdiv_defines.hh b/source/blender/draw/intern/draw_subdiv_defines.hh
index d6f5698c9cc..a23b9977a52 100644
--- a/source/blender/draw/intern/draw_subdiv_defines.hh
+++ b/source/blender/draw/intern/draw_subdiv_defines.hh
@@ -16,6 +16,8 @@
 #define SHADER_DATA_BUF_SLOT 0
 
 /* Storage buffer bindings */
+#define SUBDIV_FACE_OFFSET_BUF_SLOT 0
+
 #define NORMALS_FINALIZE_VERTEX_NORMALS_BUF_SLOT 0
 #define NORMALS_FINALIZE_VERTEX_LOOP_MAP_BUF_SLOT 1
 #define NORMALS_FINALIZE_POS_NOR_BUF_SLOT 2
diff --git a/source/blender/draw/intern/shaders/subdiv_info.hh b/source/blender/draw/intern/shaders/subdiv_info.hh
index 98406798aca..4544d43091d 100644
--- a/source/blender/draw/intern/shaders/subdiv_info.hh
+++ b/source/blender/draw/intern/shaders/subdiv_info.hh
@@ -19,6 +19,12 @@ TYPEDEF_SOURCE("draw_subdiv_shader_shared.hh")
 UNIFORM_BUF(SHADER_DATA_BUF_SLOT, DRWSubdivUboStorage, shader_data)
 GPU_SHADER_CREATE_END()
 
+GPU_SHADER_CREATE_INFO(subdiv_polygon_offset_base)
+DEFINE("SUBDIV_POLYGON_OFFSET")
+STORAGE_BUF(SUBDIV_FACE_OFFSET_BUF_SLOT, READ, uint, subdiv_face_offset[])
+ADDITIONAL_INFO(subdiv_base)
+GPU_SHADER_CREATE_END()
+
 /* -------------------------------------------------------------------- */
 /** \name Normals Finalize
  * \{ */
diff --git a/source/blender/draw/intern/shaders/subdiv_lib.glsl b/source/blender/draw/intern/shaders/subdiv_lib.glsl
index 0b9c9508d6e..4a3d993dc48 100644
--- a/source/blender/draw/intern/shaders/subdiv_lib.glsl
+++ b/source/blender/draw/intern/shaders/subdiv_lib.glsl
@@ -8,7 +8,11 @@
 
 #ifdef USE_GPU_SHADER_CREATE_INFO
 /* TODO: Do not use compute variables directly in a library. */
+#  ifdef SUBDIV_POLYGON_OFFSET
+COMPUTE_SHADER_CREATE_INFO(subdiv_polygon_offset_base)
+#  else
 COMPUTE_SHADER_CREATE_INFO(subdiv_base)
+#  endif
 #else
 
 layout(local_size_x = 64, local_size_y = 1, local_size_z = 1) in;
@@ -210,4 +214,6 @@ uint coarse_face_index_from_subdiv_quad_index(uint subdiv_quad_index, uint coars
 
   return first - 1;
 }
+#else
+uint coarse_face_index_from_subdiv_quad_index(uint subdiv_quad_index, uint coarse_face_count);
 #endif