vbo: also map the immediate mode buffer for read

because we read from it sometimes and we want cached reads.

We can only do it with the persistent mapping, because the non-persistent
mapping uses incompatible flags.

Reviewed-by: Mathias Fröhlich <mathias.froehlich@web.de>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3766>

diff --git a/src/mesa/vbo/vbo_exec_draw.c b/src/mesa/vbo/vbo_exec_draw.c
index a46a2b035682e8274be9f3c4604e7b956e7e5260..7c3b7ef4330e766787867ada197cfe311c45c351 100644 (file)
--- a/src/mesa/vbo/vbo_exec_draw.c
+++ b/src/mesa/vbo/vbo_exec_draw.c
@@ -286,8 +286,13 @@ vbo_exec_vtx_map(struct vbo_exec_context *exec)
                         GL_MAP_UNSYNCHRONIZED_BIT;
 
    if (ctx->Extensions.ARB_buffer_storage) {
+      /* We sometimes read from the buffer, so map it for read too.
+       * Only the persistent mapping can do that, because the non-persistent
+       * mapping uses flags that are incompatible with GL_MAP_READ_BIT.
+       */
       accessRange |= GL_MAP_PERSISTENT_BIT |
-                     GL_MAP_COHERENT_BIT;
+                     GL_MAP_COHERENT_BIT |
+                     GL_MAP_READ_BIT;
    } else {
       accessRange |= GL_MAP_INVALIDATE_RANGE_BIT |
                      GL_MAP_FLUSH_EXPLICIT_BIT |
@@ -328,7 +333,8 @@ vbo_exec_vtx_map(struct vbo_exec_context *exec)
                                  GL_MAP_WRITE_BIT |
                                  (ctx->Extensions.ARB_buffer_storage ?
                                     GL_MAP_PERSISTENT_BIT |
-                                    GL_MAP_COHERENT_BIT : 0) |
+                                    GL_MAP_COHERENT_BIT |
+                                    GL_MAP_READ_BIT : 0) |
                                  GL_DYNAMIC_STORAGE_BIT |
                                  GL_CLIENT_STORAGE_BIT,
                                  exec->vtx.bufferobj)) {