Revert "DrawManager: Use Compute Shader to Update Hair."

This reverts commit 8f9599d17e80254928d2d72081a4c7e0dee64038.

Mac seems to have an error with this change.
```
                 ERROR: /Users/blender/git/blender-vdev/blender.git/source/blender/draw/intern/draw_hair.c:115:44: error: use of undeclared identifier 'shader_src'
                 ERROR: /Users/blender/git/blender-vdev/blender.git/source/blender/draw/intern/draw_hair.c:123:13: error: use of undeclared identifier 'shader_src'
                 ERROR: make[2]: *** [source/blender/draw/CMakeFiles/bf_draw.dir/intern/draw_hair.c.o] Error 1
                 ERROR: make[1]: *** [source/blender/draw/CMakeFiles/bf_draw.dir/all] Error 2
                 ERROR: make: *** [all] Error 2

```

10 files changed, 82 insertions, 270 deletions

diff --git a/source/blender/draw/CMakeLists.txt b/source/blender/draw/CMakeLists.txt
index 95c0f5d300c..045adf4b380 100644
--- a/source/blender/draw/CMakeLists.txt
+++ b/source/blender/draw/CMakeLists.txt
@@ -321,7 +321,6 @@ data_to_c_simple(intern/shaders/common_globals_lib.glsl SRC)
 data_to_c_simple(intern/shaders/common_pointcloud_lib.glsl SRC)
 data_to_c_simple(intern/shaders/common_hair_lib.glsl SRC)
 data_to_c_simple(intern/shaders/common_hair_refine_vert.glsl SRC)
-data_to_c_simple(intern/shaders/common_hair_refine_comp.glsl SRC)
 data_to_c_simple(intern/shaders/common_math_lib.glsl SRC)
 data_to_c_simple(intern/shaders/common_math_geom_lib.glsl SRC)
 data_to_c_simple(intern/shaders/common_view_lib.glsl SRC)
diff --git a/source/blender/draw/intern/DRW_render.h b/source/blender/draw/intern/DRW_render.h
index 5071658fd82..2545cfa65dc 100644
--- a/source/blender/draw/intern/DRW_render.h
+++ b/source/blender/draw/intern/DRW_render.h
@@ -438,10 +438,6 @@ void DRW_shgroup_call_range(
 void DRW_shgroup_call_instance_range(
     DRWShadingGroup *shgroup, Object *ob, struct GPUBatch *geom, uint i_sta, uint i_ct);
 
-void DRW_shgroup_call_compute(DRWShadingGroup *shgroup,
-                              int groups_x_len,
-                              int groups_y_len,
-                              int groups_z_len);
 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);
@@ -579,9 +575,6 @@ void DRW_shgroup_uniform_vec4_array_copy(DRWShadingGroup *shgroup,
                                          const char *name,
                                          const float (*value)[4],
                                          int arraysize);
-void DRW_shgroup_vertex_buffer(DRWShadingGroup *shgroup,
-                               const char *name,
-                               struct GPUVertBuf *vertex_buffer);
 
 bool DRW_shgroup_is_empty(DRWShadingGroup *shgroup);
 
diff --git a/source/blender/draw/intern/draw_cache_impl_hair.c b/source/blender/draw/intern/draw_cache_impl_hair.c
index 6424b21666d..fd28ac00186 100644
--- a/source/blender/draw/intern/draw_cache_impl_hair.c
+++ b/source/blender/draw/intern/draw_cache_impl_hair.c
@@ -243,8 +243,7 @@ static void hair_batch_cache_ensure_procedural_final_points(ParticleHairCache *c
   GPUVertFormat format = {0};
   GPU_vertformat_attr_add(&format, "pos", GPU_COMP_F32, 4, GPU_FETCH_FLOAT);
 
-  cache->final[subdiv].proc_buf = GPU_vertbuf_create_with_format_ex(&format,
-                                                                    GPU_USAGE_DEVICE_ONLY);
+  cache->final[subdiv].proc_buf = GPU_vertbuf_create_with_format(&format);
 
   /* Create a destination buffer for the transform feedback. Sized appropriately */
   /* Those are points! not line segments. */
diff --git a/source/blender/draw/intern/draw_hair.c b/source/blender/draw/intern/draw_hair.c
index 258777b34fb..bca227a24e2 100644
--- a/source/blender/draw/intern/draw_hair.c
+++ b/source/blender/draw/intern/draw_hair.c
@@ -36,28 +36,15 @@
 #include "BKE_duplilist.h"
 
 #include "GPU_batch.h"
-#include "GPU_capabilities.h"
-#include "GPU_compute.h"
 #include "GPU_shader.h"
-#include "GPU_texture.h"
 #include "GPU_vertex_buffer.h"
 
 #include "draw_hair_private.h"
 
 #ifndef __APPLE__
 #  define USE_TRANSFORM_FEEDBACK
-#  define USE_COMPUTE_SHADERS
 #endif
 
-BLI_INLINE bool drw_hair_use_compute_shaders(void)
-{
-#ifdef USE_COMPUTE_SHADERS
-  return GPU_compute_shader_support();
-#else
-  return false;
-#endif
-}
-
 typedef enum ParticleRefineShader {
   PART_REFINE_CATMULL_ROM = 0,
   PART_REFINE_MAX_SHADER,
@@ -84,7 +71,6 @@ static DRWPass *g_tf_pass; /* XXX can be a problem with multiple DRWManager in t
 
 extern char datatoc_common_hair_lib_glsl[];
 extern char datatoc_common_hair_refine_vert_glsl[];
-extern char datatoc_common_hair_refine_comp_glsl[];
 extern char datatoc_gpu_shader_3D_smooth_color_frag_glsl[];
 
 static GPUShader *hair_refine_shader_get(ParticleRefineShader sh)
@@ -93,26 +79,15 @@ static GPUShader *hair_refine_shader_get(ParticleRefineShader sh)
     return g_refine_shaders[sh];
   }
 
-#ifdef USE_COMPUTE_SHADERS
-  const bool do_compute = drw_hair_use_compute_shaders();
-  if (do_compute) {
-    g_refine_shaders[sh] = GPU_shader_create_compute(datatoc_common_hair_refine_comp_glsl,
-                                                     datatoc_common_hair_lib_glsl,
-                                                     "#define HAIR_PHASE_SUBDIV\n",
-                                                     __func__);
-    return g_refine_shaders[sh];
-  }
-#endif
+  char *vert_with_lib = BLI_string_joinN(datatoc_common_hair_lib_glsl,
+                                         datatoc_common_hair_refine_vert_glsl);
 
 #ifdef USE_TRANSFORM_FEEDBACK
-  char *shader_src = BLI_string_joinN(datatoc_common_hair_lib_glsl,
-                                      datatoc_common_hair_refine_vert_glsl);
   const char *var_names[1] = {"finalColor"};
   g_refine_shaders[sh] = DRW_shader_create_with_transform_feedback(
-      shader_src, NULL, "#define HAIR_PHASE_SUBDIV\n", GPU_SHADER_TFB_POINTS, var_names, 1);
-
+      vert_with_lib, NULL, "#define HAIR_PHASE_SUBDIV\n", GPU_SHADER_TFB_POINTS, var_names, 1);
 #else
-  g_refine_shaders[sh] = DRW_shader_create(shader_src,
+  g_refine_shaders[sh] = DRW_shader_create(vert_with_lib,
                                            NULL,
                                            datatoc_gpu_shader_3D_smooth_color_frag_glsl,
                                            "#define blender_srgb_to_framebuffer_space(a) a\n"
@@ -120,14 +95,14 @@ static GPUShader *hair_refine_shader_get(ParticleRefineShader sh)
                                            "#define TF_WORKAROUND\n");
 #endif
 
-  MEM_freeN(shader_src);
+  MEM_freeN(vert_with_lib);
 
   return g_refine_shaders[sh];
 }
 
 void DRW_hair_init(void)
 {
-#if defined(USE_TRANSFORM_FEEDBACK) || defined(USE_COMPUTE_SHADERS)
+#ifdef USE_TRANSFORM_FEEDBACK
   g_tf_pass = DRW_pass_create("Update Hair Pass", 0);
 #else
   g_tf_pass = DRW_pass_create("Update Hair Pass", DRW_STATE_WRITE_COLOR);
@@ -150,67 +125,6 @@ void DRW_hair_init(void)
   }
 }
 
-static void drw_hair_particle_cache_shgrp_attach_resources(DRWShadingGroup *shgrp,
-                                                           ParticleHairCache *cache,
-                                                           const int subdiv)
-{
-  DRW_shgroup_uniform_texture(shgrp, "hairPointBuffer", cache->point_tex);
-  DRW_shgroup_uniform_texture(shgrp, "hairStrandBuffer", cache->strand_tex);
-  DRW_shgroup_uniform_texture(shgrp, "hairStrandSegBuffer", cache->strand_seg_tex);
-  DRW_shgroup_uniform_int(shgrp, "hairStrandsRes", &cache->final[subdiv].strands_res, 1);
-}
-
-static void drw_hair_particle_cache_update_compute(ParticleHairCache *cache, const int subdiv)
-{
-  const int strands_len = cache->strands_len;
-  const int final_points_len = cache->final[subdiv].strands_res * strands_len;
-  if (final_points_len > 0) {
-    GPUShader *shader = hair_refine_shader_get(PART_REFINE_CATMULL_ROM);
-    DRWShadingGroup *shgrp = DRW_shgroup_create(shader, g_tf_pass);
-    drw_hair_particle_cache_shgrp_attach_resources(shgrp, cache, subdiv);
-    DRW_shgroup_vertex_buffer(shgrp, "hairPointOutputBuffer", cache->final[subdiv].proc_buf);
-
-    const int max_strands_per_call = GPU_max_work_group_count(0);
-    int strands_start = 0;
-    while (strands_start < strands_len) {
-      int batch_strands_len = MIN2(strands_len - strands_start, max_strands_per_call);
-      DRWShadingGroup *subgroup = DRW_shgroup_create_sub(shgrp);
-      DRW_shgroup_uniform_int_copy(subgroup, "hairStrandOffset", strands_start);
-      DRW_shgroup_call_compute(subgroup, batch_strands_len, cache->final[subdiv].strands_res, 1);
-      strands_start += batch_strands_len;
-    }
-  }
-}
-
-static void drw_hair_particle_cache_update_transform_feedback(ParticleHairCache *cache,
-                                                              const int subdiv)
-{
-  const int final_points_len = cache->final[subdiv].strands_res * cache->strands_len;
-  if (final_points_len > 0) {
-    GPUShader *tf_shader = hair_refine_shader_get(PART_REFINE_CATMULL_ROM);
-
-#ifdef USE_TRANSFORM_FEEDBACK
-    DRWShadingGroup *tf_shgrp = DRW_shgroup_transform_feedback_create(
-        tf_shader, g_tf_pass, cache->final[subdiv].proc_buf);
-#else
-    DRWShadingGroup *tf_shgrp = DRW_shgroup_create(tf_shader, g_tf_pass);
-
-    ParticleRefineCall *pr_call = MEM_mallocN(sizeof(*pr_call), __func__);
-    pr_call->next = g_tf_calls;
-    pr_call->vbo = cache->final[subdiv].proc_buf;
-    pr_call->shgrp = tf_shgrp;
-    pr_call->vert_len = final_points_len;
-    g_tf_calls = pr_call;
-    DRW_shgroup_uniform_int(tf_shgrp, "targetHeight", &g_tf_target_height, 1);
-    DRW_shgroup_uniform_int(tf_shgrp, "targetWidth", &g_tf_target_width, 1);
-    DRW_shgroup_uniform_int(tf_shgrp, "idOffset", &g_tf_id_offset, 1);
-#endif
-
-    drw_hair_particle_cache_shgrp_attach_resources(tf_shgrp, cache, subdiv);
-    DRW_shgroup_call_procedural_points(tf_shgrp, NULL, final_points_len);
-  }
-}
-
 static ParticleHairCache *drw_hair_particle_cache_get(
     Object *object, ParticleSystem *psys, ModifierData *md, int subdiv, int thickness_res)
 {
@@ -226,11 +140,32 @@ static ParticleHairCache *drw_hair_particle_cache_get(
   }
 
   if (update) {
-    if (drw_hair_use_compute_shaders()) {
-      drw_hair_particle_cache_update_compute(cache, subdiv);
-    }
-    else {
-      drw_hair_particle_cache_update_transform_feedback(cache, subdiv);
+    int final_points_len = cache->final[subdiv].strands_res * cache->strands_len;
+    if (final_points_len > 0) {
+      GPUShader *tf_shader = hair_refine_shader_get(PART_REFINE_CATMULL_ROM);
+
+#ifdef USE_TRANSFORM_FEEDBACK
+      DRWShadingGroup *tf_shgrp = DRW_shgroup_transform_feedback_create(
+          tf_shader, g_tf_pass, cache->final[subdiv].proc_buf);
+#else
+      DRWShadingGroup *tf_shgrp = DRW_shgroup_create(tf_shader, g_tf_pass);
+
+      ParticleRefineCall *pr_call = MEM_mallocN(sizeof(*pr_call), __func__);
+      pr_call->next = g_tf_calls;
+      pr_call->vbo = cache->final[subdiv].proc_buf;
+      pr_call->shgrp = tf_shgrp;
+      pr_call->vert_len = final_points_len;
+      g_tf_calls = pr_call;
+      DRW_shgroup_uniform_int(tf_shgrp, "targetHeight", &g_tf_target_height, 1);
+      DRW_shgroup_uniform_int(tf_shgrp, "targetWidth", &g_tf_target_width, 1);
+      DRW_shgroup_uniform_int(tf_shgrp, "idOffset", &g_tf_id_offset, 1);
+#endif
+
+      DRW_shgroup_uniform_texture(tf_shgrp, "hairPointBuffer", cache->point_tex);
+      DRW_shgroup_uniform_texture(tf_shgrp, "hairStrandBuffer", cache->strand_tex);
+      DRW_shgroup_uniform_texture(tf_shgrp, "hairStrandSegBuffer", cache->strand_seg_tex);
+      DRW_shgroup_uniform_int(tf_shgrp, "hairStrandsRes", &cache->final[subdiv].strands_res, 1);
+      DRW_shgroup_call_procedural_points(tf_shgrp, NULL, final_points_len);
     }
   }
   return cache;
@@ -432,11 +367,9 @@ void DRW_hair_update(void)
   MEM_freeN(data);
   GPU_framebuffer_free(fb);
 #else
-  /* Just render the pass when using compute shaders or transform feedback. */
+  /* TODO(fclem): replace by compute shader. */
+  /* Just render using transform feedback. */
   DRW_draw_pass(g_tf_pass);
-  if (drw_hair_use_compute_shaders()) {
-    GPU_memory_barrier(GPU_BARRIER_SHADER_STORAGE);
-  }
 #endif
 }
 
diff --git a/source/blender/draw/intern/draw_manager.h b/source/blender/draw/intern/draw_manager.h
index d4e22c83798..84bc0327aa2 100644
--- a/source/blender/draw/intern/draw_manager.h
+++ b/source/blender/draw/intern/draw_manager.h
@@ -187,10 +187,6 @@ 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,
@@ -228,12 +224,6 @@ 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;
@@ -270,7 +260,6 @@ typedef union DRWCommand {
   DRWCommandDrawInstance instance;
   DRWCommandDrawInstanceRange instance_range;
   DRWCommandDrawProcedural procedural;
-  DRWCommandCompute compute;
   DRWCommandSetMutableState state;
   DRWCommandSetStencil stencil;
   DRWCommandSetSelectID select_id;
@@ -285,7 +274,6 @@ struct DRWCallBuffer {
 };
 
 /** Used by #DRWUniform.type */
-/* TODO(jbakker): rename to DRW_RESOURCE/DRWResourceType. */
 typedef enum {
   DRW_UNIFORM_INT = 0,
   DRW_UNIFORM_INT_COPY,
@@ -298,7 +286,6 @@ 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,
diff --git a/source/blender/draw/intern/draw_manager_data.c b/source/blender/draw/intern/draw_manager_data.c
index 3b852e7f8c8..6bdc5305fed 100644
--- a/source/blender/draw/intern/draw_manager_data.c
+++ b/source/blender/draw/intern/draw_manager_data.c
@@ -47,7 +47,6 @@
 #endif
 
 #include "GPU_buffers.h"
-#include "GPU_capabilities.h"
 #include "GPU_material.h"
 #include "GPU_uniform_buffer.h"
 
@@ -447,19 +446,6 @@ void DRW_shgroup_uniform_vec4_array_copy(DRWShadingGroup *shgroup,
   }
 }
 
-void DRW_shgroup_vertex_buffer(DRWShadingGroup *shgroup,
-                               const char *name,
-                               GPUVertBuf *vertex_buffer)
-{
-  int location = GPU_shader_get_ssbo(shgroup->shader, name);
-  if (location == -1) {
-    BLI_assert(false && "Unable to locate binding of shader storage buffer objects.");
-    return;
-  }
-  drw_shgroup_uniform_create_ex(
-      shgroup, location, DRW_UNIFORM_VERTEX_BUFFER_AS_STORAGE, vertex_buffer, 0, 0, 1);
-}
-
 /** \} */
 
 /* -------------------------------------------------------------------- */
@@ -714,17 +700,6 @@ static void drw_command_draw_intance_range(
   cmd->inst_count = count;
 }
 
-static void drw_command_compute(DRWShadingGroup *shgroup,
-                                int groups_x_len,
-                                int groups_y_len,
-                                int groups_z_len)
-{
-  DRWCommandCompute *cmd = drw_command_create(shgroup, DRW_CMD_COMPUTE);
-  cmd->groups_x_len = groups_x_len;
-  cmd->groups_y_len = groups_y_len;
-  cmd->groups_z_len = groups_z_len;
-}
-
 static void drw_command_draw_procedural(DRWShadingGroup *shgroup,
                                         GPUBatch *batch,
                                         DRWResourceHandle handle,
@@ -840,17 +815,6 @@ void DRW_shgroup_call_instance_range(
   drw_command_draw_intance_range(shgroup, geom, handle, i_sta, i_ct);
 }
 
-void DRW_shgroup_call_compute(DRWShadingGroup *shgroup,
-                              int groups_x_len,
-                              int groups_y_len,
-                              int groups_z_len)
-{
-  BLI_assert(groups_x_len > 0 && groups_y_len > 0 && groups_z_len > 0);
-  BLI_assert(GPU_compute_shader_support());
-
-  drw_command_compute(shgroup, groups_x_len, groups_y_len, groups_z_len);
-}
-
 static void drw_shgroup_call_procedural_add_ex(DRWShadingGroup *shgroup,
                                                GPUBatch *geom,
                                                Object *ob,
diff --git a/source/blender/draw/intern/draw_manager_exec.c b/source/blender/draw/intern/draw_manager_exec.c
index f29caebeb84..4c8fcb0e016 100644
--- a/source/blender/draw/intern/draw_manager_exec.c
+++ b/source/blender/draw/intern/draw_manager_exec.c
@@ -29,7 +29,6 @@
 
 #include "BKE_global.h"
 
-#include "GPU_compute.h"
 #include "GPU_platform.h"
 #include "GPU_shader.h"
 #include "GPU_state.h"
@@ -673,9 +672,6 @@ static void draw_update_uniforms(DRWShadingGroup *shgroup,
           *use_tfeedback = GPU_shader_transform_feedback_enable(shgroup->shader,
                                                                 ((GPUVertBuf *)uni->pvalue));
           break;
-        case DRW_UNIFORM_VERTEX_BUFFER_AS_STORAGE:
-          GPU_vertbuf_bind_as_ssbo((GPUVertBuf *)uni->pvalue, uni->location);
-          break;
           /* Legacy/Fallback support. */
         case DRW_UNIFORM_BASE_INSTANCE:
           state->baseinst_loc = uni->location;
@@ -1054,12 +1050,6 @@ static void draw_shgroup(DRWShadingGroup *shgroup, DRWState pass_state)
                               cmd->instance_range.inst_count,
                               false);
           break;
-        case DRW_CMD_COMPUTE:
-          GPU_compute_dispatch(shgroup->shader,
-                               cmd->compute.groups_x_len,
-                               cmd->compute.groups_y_len,
-                               cmd->compute.groups_z_len);
-          break;
       }
     }
 
diff --git a/source/blender/draw/intern/shaders/common_hair_lib.glsl b/source/blender/draw/intern/shaders/common_hair_lib.glsl
index 02c335ddae2..8684d82f228 100644
--- a/source/blender/draw/intern/shaders/common_hair_lib.glsl
+++ b/source/blender/draw/intern/shaders/common_hair_lib.glsl
@@ -28,9 +28,6 @@ uniform bool hairCloseTip = true;
 
 uniform vec4 hairDupliMatrix[4];
 
-/* Strand batch offset when used in compute shaders. */
-uniform int hairStrandOffset = 0;
-
 /* -- Per control points -- */
 uniform samplerBuffer hairPointBuffer; /* RGBA32F */
 #define point_position xyz
@@ -46,37 +43,13 @@ uniform usamplerBuffer hairStrandSegBuffer; /* R16UI */
 
 /* -- Subdivision stage -- */
 /**
- * We use a transform feedback or compute shader to preprocess the strands and add more subdivision
- * to it. For the moment these are simple smooth interpolation but one could hope to see the full
+ * We use a transform feedback to preprocess the strands and add more subdivision to it.
+ * For the moment these are simple smooth interpolation but one could hope to see the full
  * children particle modifiers being evaluated at this stage.
  *
  * If no more subdivision is needed, we can skip this step.
  */
 
-#ifdef GPU_VERTEX_SHADER
-float hair_get_local_time()
-{
-  return float(gl_VertexID % hairStrandsRes) / float(hairStrandsRes - 1);
-}
-
-int hair_get_id()
-{
-  return gl_VertexID / hairStrandsRes;
-}
-#endif
-
-#ifdef GPU_COMPUTE_SHADER
-float hair_get_local_time()
-{
-  return float(gl_GlobalInvocationID.y) / float(hairStrandsRes - 1);
-}
-
-int hair_get_id()
-{
-  return int(gl_GlobalInvocationID.x) + hairStrandOffset;
-}
-#endif
-
 #ifdef HAIR_PHASE_SUBDIV
 int hair_get_base_id(float local_time, int strand_segments, out float interp_time)
 {
@@ -91,9 +64,9 @@ int hair_get_base_id(float local_time, int strand_segments, out float interp_tim
 void hair_get_interp_attrs(
     out vec4 data0, out vec4 data1, out vec4 data2, out vec4 data3, out float interp_time)
 {
-  float local_time = hair_get_local_time();
+  float local_time = float(gl_VertexID % hairStrandsRes) / float(hairStrandsRes - 1);
 
-  int hair_id = hair_get_id();
+  int hair_id = gl_VertexID / hairStrandsRes;
   int strand_offset = int(texelFetch(hairStrandBuffer, hair_id).x);
   int strand_segments = int(texelFetch(hairStrandSegBuffer, hair_id).x);
 
@@ -123,7 +96,6 @@ void hair_get_interp_attrs(
  */
 
 #if !defined(HAIR_PHASE_SUBDIV) && defined(GPU_VERTEX_SHADER)
-
 int hair_get_strand_id(void)
 {
   return gl_VertexID / (hairStrandsRes * hairThicknessRes);
@@ -255,45 +227,3 @@ vec2 hair_resolve_barycentric(vec2 vert_barycentric)
     return vec2(1.0 - vert_barycentric.x, 0.0);
   }
 }
-
-/* Hair interpolation functions. */
-vec4 hair_get_weights_cardinal(float t)
-{
-  float t2 = t * t;
-  float t3 = t2 * t;
-#if defined(CARDINAL)
-  float fc = 0.71;
-#else /* defined(CATMULL_ROM) */
-  float fc = 0.5;
-#endif
-
-  vec4 weights;
-  /* GLSL Optimized version of key_curve_position_weights() */
-  float fct = t * fc;
-  float fct2 = t2 * fc;
-  float fct3 = t3 * fc;
-  weights.x = (fct2 * 2.0 - fct3) - fct;
-  weights.y = (t3 * 2.0 - fct3) + (-t2 * 3.0 + fct2) + 1.0;
-  weights.z = (-t3 * 2.0 + fct3) + (t2 * 3.0 - (2.0 * fct2)) + fct;
-  weights.w = fct3 - fct2;
-  return weights;
-}
-
-/* TODO(fclem): This one is buggy, find why. (it's not the optimization!!) */
-vec4 hair_get_weights_bspline(float t)
-{
-  float t2 = t * t;
-  float t3 = t2 * t;
-
-  vec4 weights;
-  /* GLSL Optimized version of key_curve_position_weights() */
-  weights.xz = vec2(-0.16666666, -0.5) * t3 + (0.5 * t2 + 0.5 * vec2(-t, t) + 0.16666666);
-  weights.y = (0.5 * t3 - t2 + 0.66666666);
-  weights.w = (0.16666666 * t3);
-  return weights;
-}
-
-vec4 hair_interp_data(vec4 v0, vec4 v1, vec4 v2, vec4 v3, vec4 w)
-{
-  return v0 * w.x + v1 * w.y + v2 * w.z + v3 * w.w;
-}
diff --git a/source/blender/draw/intern/shaders/common_hair_refine_comp.glsl b/source/blender/draw/intern/shaders/common_hair_refine_comp.glsl
deleted file mode 100644
index 4dcde4b0245..00000000000
--- a/source/blender/draw/intern/shaders/common_hair_refine_comp.glsl
+++ /dev/null
@@ -1,24 +0,0 @@
-
-/*
- * To be compiled with common_hair_lib.glsl.
- */
-
-layout(local_size_x = 1, local_size_y = 1) in;
-layout(std430, binding = 0) writeonly buffer hairPointOutputBuffer
-{
-  vec4 posTime[];
-}
-out_vertbuf;
-
-void main(void)
-{
-  float interp_time;
-  vec4 data0, data1, data2, data3;
-  hair_get_interp_attrs(data0, data1, data2, data3, interp_time);
-
-  vec4 weights = hair_get_weights_cardinal(interp_time);
-  vec4 result = hair_interp_data(data0, data1, data2, data3, weights);
-
-  uint index = uint(hair_get_id() * hairStrandsRes) + gl_GlobalInvocationID.y;
-  out_vertbuf.posTime[index] = result;
-}
diff --git a/source/blender/draw/intern/shaders/common_hair_refine_vert.glsl b/source/blender/draw/intern/shaders/common_hair_refine_vert.glsl
index 371d43827b9..3f5e3f8226f 100644
--- a/source/blender/draw/intern/shaders/common_hair_refine_vert.glsl
+++ b/source/blender/draw/intern/shaders/common_hair_refine_vert.glsl
@@ -3,6 +3,47 @@
 
 out vec4 finalColor;
 
+vec4 get_weights_cardinal(float t)
+{
+  float t2 = t * t;
+  float t3 = t2 * t;
+#if defined(CARDINAL)
+  float fc = 0.71;
+#else /* defined(CATMULL_ROM) */
+  float fc = 0.5;
+#endif
+
+  vec4 weights;
+  /* GLSL Optimized version of key_curve_position_weights() */
+  float fct = t * fc;
+  float fct2 = t2 * fc;
+  float fct3 = t3 * fc;
+  weights.x = (fct2 * 2.0 - fct3) - fct;
+  weights.y = (t3 * 2.0 - fct3) + (-t2 * 3.0 + fct2) + 1.0;
+  weights.z = (-t3 * 2.0 + fct3) + (t2 * 3.0 - (2.0 * fct2)) + fct;
+  weights.w = fct3 - fct2;
+  return weights;
+}
+
+/* TODO(fclem): This one is buggy, find why. (it's not the optimization!!) */
+vec4 get_weights_bspline(float t)
+{
+  float t2 = t * t;
+  float t3 = t2 * t;
+
+  vec4 weights;
+  /* GLSL Optimized version of key_curve_position_weights() */
+  weights.xz = vec2(-0.16666666, -0.5) * t3 + (0.5 * t2 + 0.5 * vec2(-t, t) + 0.16666666);
+  weights.y = (0.5 * t3 - t2 + 0.66666666);
+  weights.w = (0.16666666 * t3);
+  return weights;
+}
+
+vec4 interp_data(vec4 v0, vec4 v1, vec4 v2, vec4 v3, vec4 w)
+{
+  return v0 * w.x + v1 * w.y + v2 * w.z + v3 * w.w;
+}
+
 #ifdef TF_WORKAROUND
 uniform int targetWidth;
 uniform int targetHeight;
@@ -15,8 +56,8 @@ void main(void)
   vec4 data0, data1, data2, data3;
   hair_get_interp_attrs(data0, data1, data2, data3, interp_time);
 
-  vec4 weights = hair_get_weights_cardinal(interp_time);
-  finalColor = hair_interp_data(data0, data1, data2, data3, weights);
+  vec4 weights = get_weights_cardinal(interp_time);
+  finalColor = interp_data(data0, data1, data2, data3, weights);
 
 #ifdef TF_WORKAROUND
   int id = gl_VertexID - idOffset;