Fix T93179: geonodes UVs and Vertex colors do not work in EEVEE

Overwriting UV map or vertex color data in Geometry nodes will move the
layers to another CustomData channel, and as such, will make attribute
lookup fail from the UVMap and Vertex Color nodes in EEVEE as the
CustomDataType will also be modified (i.e. no longer `CD_MTFACE` or
`CD_MCOL`).

As discussed in T93179, the solution is to use `CD_PROP_AUTO_FROM_NAME`
so that the render engine is able to find the attributes. This also makes
EEVEE emulate Cycles behaviour in this regard. `attr_load_uv` and
`attr_load_color` are also removed in favor of the generic attribute
API in the various GLSL shaders.

Although `CD_PROP_AUTO_FROM_NAME` is now used even for UV maps, the
active UV map is still used in case the attribute name is empty, to
preserve the old behavior.

Differential Revision: https://developer.blender.org/D13730

1 files changed, 5 insertions, 11 deletions

diff --git a/source/blender/draw/intern/draw_cache_impl_particles.c b/source/blender/draw/intern/draw_cache_impl_particles.c
index 0f1ab967ca5..a1c0a42ba6f 100644
--- a/source/blender/draw/intern/draw_cache_impl_particles.c
+++ b/source/blender/draw/intern/draw_cache_impl_particles.c
@@ -875,14 +875,13 @@ static void particle_batch_cache_ensure_procedural_strand_data(PTCacheEdit *edit
     GPU_vertformat_safe_attr_name(name, attr_safe_name, GPU_MAX_SAFE_ATTR_NAME);
 
     int n = 0;
-    BLI_snprintf(cache->uv_layer_names[i][n++], MAX_LAYER_NAME_LEN, "u%s", attr_safe_name);
     BLI_snprintf(cache->uv_layer_names[i][n++], MAX_LAYER_NAME_LEN, "a%s", attr_safe_name);
 
     if (i == active_uv) {
       BLI_strncpy(cache->uv_layer_names[i][n++], "au", MAX_LAYER_NAME_LEN);
     }
     if (i == render_uv) {
-      BLI_strncpy(cache->uv_layer_names[i][n++], "u", MAX_LAYER_NAME_LEN);
+      BLI_strncpy(cache->uv_layer_names[i][n++], "a", MAX_LAYER_NAME_LEN);
     }
   }
   /* Vertex colors */
@@ -896,12 +895,7 @@ static void particle_batch_cache_ensure_procedural_strand_data(PTCacheEdit *edit
     GPU_vertformat_safe_attr_name(name, attr_safe_name, GPU_MAX_SAFE_ATTR_NAME);
 
     int n = 0;
-    BLI_snprintf(cache->col_layer_names[i][n++], MAX_LAYER_NAME_LEN, "c%s", attr_safe_name);
-
-    /* We only do vcols auto name that are not overridden by uvs */
-    if (CustomData_get_named_layer_index(&psmd->mesh_final->ldata, CD_MLOOPUV, name) == -1) {
-      BLI_snprintf(cache->col_layer_names[i][n++], MAX_LAYER_NAME_LEN, "a%s", attr_safe_name);
-    }
+    BLI_snprintf(cache->col_layer_names[i][n++], MAX_LAYER_NAME_LEN, "a%s", attr_safe_name);
 
     if (i == active_col) {
       BLI_strncpy(cache->col_layer_names[i][n++], "ac", MAX_LAYER_NAME_LEN);
@@ -1186,11 +1180,11 @@ static void particle_batch_cache_ensure_pos_and_seg(PTCacheEdit *edit,
       const char *name = CustomData_get_layer_name(&psmd->mesh_final->ldata, CD_MLOOPUV, i);
       GPU_vertformat_safe_attr_name(name, attr_safe_name, GPU_MAX_SAFE_ATTR_NAME);
 
-      BLI_snprintf(uuid, sizeof(uuid), "u%s", attr_safe_name);
+      BLI_snprintf(uuid, sizeof(uuid), "a%s", attr_safe_name);
       uv_id[i] = GPU_vertformat_attr_add(&format, uuid, GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
 
       if (i == active_uv) {
-        GPU_vertformat_alias_add(&format, "u");
+        GPU_vertformat_alias_add(&format, "a");
       }
     }
 
@@ -1200,7 +1194,7 @@ static void particle_batch_cache_ensure_pos_and_seg(PTCacheEdit *edit,
           &psmd->mesh_final->ldata, CD_PROP_BYTE_COLOR, i);
       GPU_vertformat_safe_attr_name(name, attr_safe_name, GPU_MAX_SAFE_ATTR_NAME);
 
-      BLI_snprintf(uuid, sizeof(uuid), "c%s", attr_safe_name);
+      BLI_snprintf(uuid, sizeof(uuid), "a%s", attr_safe_name);
       col_id[i] = GPU_vertformat_attr_add(&format, uuid, GPU_COMP_U16, 4, GPU_FETCH_FLOAT);
 
       if (i == active_col) {