Rework viewport capture in preview generation

1 files changed, 29 insertions, 2 deletions

diff --git a/editor/editor_resource_preview.cpp b/editor/editor_resource_preview.cpp
index bae7887c02..fc1dda9669 100644
--- a/editor/editor_resource_preview.cpp
+++ b/editor/editor_resource_preview.cpp
@@ -95,8 +95,35 @@ void EditorResourcePreviewGenerator::_bind_methods() {
 EditorResourcePreviewGenerator::EditorResourcePreviewGenerator() {
 }
 
+void EditorResourcePreviewGenerator::DrawRequester::request_and_wait(RID p_viewport) const {
+	if (EditorResourcePreview::get_singleton()->is_threaded()) {
+		Callable request_vp_update_once = callable_mp(RS::get_singleton(), &RS::viewport_set_update_mode).bind(p_viewport, RS::VIEWPORT_UPDATE_ONCE);
+		RS::get_singleton()->connect(SNAME("frame_pre_draw"), request_vp_update_once, Object::CONNECT_ONE_SHOT);
+		RS::get_singleton()->request_frame_drawn_callback(callable_mp(const_cast<EditorResourcePreviewGenerator::DrawRequester *>(this), &EditorResourcePreviewGenerator::DrawRequester::_post_semaphore));
+
+		semaphore.wait();
+	} else {
+		RS::get_singleton()->draw(false);
+	}
+}
+
+void EditorResourcePreviewGenerator::DrawRequester::abort() const {
+	if (EditorResourcePreview::get_singleton()->is_threaded()) {
+		semaphore.post();
+	}
+}
+
+Variant EditorResourcePreviewGenerator::DrawRequester::_post_semaphore() const {
+	semaphore.post();
+	return Variant(); // Needed because of how the callback is used.
+}
+
 EditorResourcePreview *EditorResourcePreview::singleton = nullptr;
 
+bool EditorResourcePreview::is_threaded() const {
+	return RSG::texture_storage->can_create_resources_async();
+}
+
 void EditorResourcePreview::_thread_func(void *ud) {
 	EditorResourcePreview *erp = (EditorResourcePreview *)ud;
 	erp->_thread();
@@ -470,7 +497,7 @@ void EditorResourcePreview::start() {
 		return;
 	}
 
-	if (RSG::texture_storage->can_create_resources_async()) {
+	if (is_threaded()) {
 		ERR_FAIL_COND_MSG(thread.is_started(), "Thread already started.");
 		thread.start(_thread_func, this);
 	} else {
@@ -481,7 +508,7 @@ void EditorResourcePreview::start() {
 }
 
 void EditorResourcePreview::stop() {
-	if (RSG::texture_storage->can_create_resources_async()) {
+	if (is_threaded()) {
 		if (thread.is_started()) {
 			exiting.set();
 			preview_sem.post();