EEVEE: Hair: Fix wrong color when using color attribute without actual data

1 files changed, 26 insertions, 4 deletions

diff --git a/source/blender/draw/intern/draw_hair.c b/source/blender/draw/intern/draw_hair.c
index 847f5e7a224..c88071dc6d6 100644
--- a/source/blender/draw/intern/draw_hair.c
+++ b/source/blender/draw/intern/draw_hair.c
@@ -36,6 +36,7 @@
 
 #include "GPU_batch.h"
 #include "GPU_shader.h"
+#include "GPU_vertex_buffer.h"
 
 #include "draw_hair_private.h"
 
@@ -62,6 +63,8 @@ static int g_tf_target_width;
 static int g_tf_target_height;
 #endif
 
+static GPUVertBuf *g_dummy_vbo = NULL;
+static GPUTexture *g_dummy_texture = NULL;
 static GPUShader *g_refine_shaders[PART_REFINE_MAX_SHADER] = {NULL};
 static DRWPass *g_tf_pass; /* XXX can be a problem with multiple DRWManager in the future */
 
@@ -102,6 +105,22 @@ void DRW_hair_init(void)
 #else
   g_tf_pass = DRW_pass_create("Update Hair Pass", DRW_STATE_WRITE_COLOR);
 #endif
+
+  if (g_dummy_vbo == NULL) {
+    /* initialize vertex format */
+    GPUVertFormat format = {0};
+    uint dummy_id = GPU_vertformat_attr_add(&format, "dummy", GPU_COMP_F32, 4, GPU_FETCH_FLOAT);
+
+    g_dummy_vbo = GPU_vertbuf_create_with_format(&format);
+
+    float vert[4] = {0.0f, 0.0f, 0.0f, 0.0f};
+    GPU_vertbuf_data_alloc(g_dummy_vbo, 1);
+    GPU_vertbuf_attr_fill(g_dummy_vbo, dummy_id, vert);
+    /* Create vbo immediately to bind to texture buffer. */
+    GPU_vertbuf_use(g_dummy_vbo);
+
+    g_dummy_texture = GPU_texture_create_from_vertbuf(g_dummy_vbo);
+  }
 }
 
 static DRWShadingGroup *drw_shgroup_create_hair_procedural_ex(Object *object,
@@ -158,12 +177,12 @@ static DRWShadingGroup *drw_shgroup_create_hair_procedural_ex(Object *object,
   /* Fix issue with certain driver not drawing anything if there is no texture bound to
    * "ac", "au", "u" or "c". */
   if (hair_cache->num_uv_layers == 0) {
-    DRW_shgroup_uniform_texture(shgrp, "u", hair_cache->final[subdiv].proc_tex);
-    DRW_shgroup_uniform_texture(shgrp, "au", hair_cache->final[subdiv].proc_tex);
+    DRW_shgroup_uniform_texture(shgrp, "u", g_dummy_texture);
+    DRW_shgroup_uniform_texture(shgrp, "au", g_dummy_texture);
   }
   if (hair_cache->num_col_layers == 0) {
-    DRW_shgroup_uniform_texture(shgrp, "c", hair_cache->final[subdiv].proc_tex);
-    DRW_shgroup_uniform_texture(shgrp, "ac", hair_cache->final[subdiv].proc_tex);
+    DRW_shgroup_uniform_texture(shgrp, "c", g_dummy_texture);
+    DRW_shgroup_uniform_texture(shgrp, "ac", g_dummy_texture);
   }
 
   if ((dupli_parent != NULL) && (dupli_object != NULL)) {
@@ -336,4 +355,7 @@ void DRW_hair_free(void)
   for (int i = 0; i < PART_REFINE_MAX_SHADER; i++) {
     DRW_SHADER_FREE_SAFE(g_refine_shaders[i]);
   }
+
+  GPU_VERTBUF_DISCARD_SAFE(g_dummy_vbo);
+  DRW_TEXTURE_FREE_SAFE(g_dummy_texture);
 }