1 files changed, 38 insertions, 11 deletions

diff --git a/source/blender/gpu/intern/gpu_context.cc b/source/blender/gpu/intern/gpu_context.cc
index 4a0a9ecc7f6..e29b0d5801d 100644
--- a/source/blender/gpu/intern/gpu_context.cc
+++ b/source/blender/gpu/intern/gpu_context.cc
@@ -27,6 +27,7 @@
 #include "gpu_batch_private.hh"
 #include "gpu_context_private.hh"
 #include "gpu_matrix_private.h"
+#include "gpu_private.h"
 
 #ifdef WITH_OPENGL_BACKEND
 #  include "gl_backend.hh"
@@ -43,6 +44,12 @@ using namespace blender::gpu;
 
 static thread_local Context *active_ctx = nullptr;
 
+static std::mutex backend_users_mutex;
+static int num_backend_users = 0;
+
+static void gpu_backend_create();
+static void gpu_backend_discard();
+
 /* -------------------------------------------------------------------- */
 /** \name gpu::Context methods
  * \{ */
@@ -85,9 +92,13 @@ Context *Context::get()
 
 GPUContext *GPU_context_create(void *ghost_window)
 {
-  if (GPUBackend::get() == nullptr) {
-    /* TODO: move where it make sense. */
-    GPU_backend_init(GPU_BACKEND_OPENGL);
+  {
+    std::scoped_lock lock(backend_users_mutex);
+    if (num_backend_users == 0) {
+      /* Automatically create backend when first context is created. */
+      gpu_backend_create();
+    }
+    num_backend_users++;
   }
 
   Context *ctx = GPUBackend::get()->context_alloc(ghost_window);
@@ -101,6 +112,16 @@ void GPU_context_discard(GPUContext *ctx_)
   Context *ctx = unwrap(ctx_);
   delete ctx;
   active_ctx = nullptr;
+
+  {
+    std::scoped_lock lock(backend_users_mutex);
+    num_backend_users--;
+    BLI_assert(num_backend_users >= 0);
+    if (num_backend_users == 0) {
+      /* Discard backend when last context is discarded. */
+      gpu_backend_discard();
+    }
+  }
 }
 
 void GPU_context_active_set(GPUContext *ctx_)
@@ -191,11 +212,12 @@ void GPU_render_step()
 /** \name Backend selection
  * \{ */
 
+static const eGPUBackendType g_backend_type = GPU_BACKEND_OPENGL;
 static GPUBackend *g_backend = nullptr;
 
-bool GPU_backend_supported(eGPUBackendType type)
+bool GPU_backend_supported(void)
 {
-  switch (type) {
+  switch (g_backend_type) {
     case GPU_BACKEND_OPENGL:
 #ifdef WITH_OPENGL_BACKEND
       return true;
@@ -214,12 +236,12 @@ bool GPU_backend_supported(eGPUBackendType type)
   }
 }
 
-void GPU_backend_init(eGPUBackendType backend_type)
+static void gpu_backend_create()
 {
   BLI_assert(g_backend == nullptr);
-  BLI_assert(GPU_backend_supported(backend_type));
+  BLI_assert(GPU_backend_supported());
 
-  switch (backend_type) {
+  switch (g_backend_type) {
 #ifdef WITH_OPENGL_BACKEND
     case GPU_BACKEND_OPENGL:
       g_backend = new GLBackend;
@@ -236,10 +258,15 @@ void GPU_backend_init(eGPUBackendType backend_type)
   }
 }
 
-void GPU_backend_exit()
+void gpu_backend_delete_resources()
+{
+  BLI_assert(g_backend);
+  g_backend->delete_resources();
+}
+
+void gpu_backend_discard()
 {
-  /* TODO: assert no resource left. Currently UI textures are still not freed in their context
-   * correctly. */
+  /* TODO: assert no resource left. */
   delete g_backend;
   g_backend = nullptr;
 }