GPUQuery: GL Backend isolation

This is part of the Vulkan task T68990.

This introduce a new GLQueryPool for managing queries in an
implementation agnostic manner.

This modify the GPU selection query to use this new object.
This also make use of blender::Vector for better code quality.

No real functionnal change.

1 files changed, 69 insertions, 0 deletions

diff --git a/source/blender/gpu/opengl/gl_query.hh b/source/blender/gpu/opengl/gl_query.hh
new file mode 100644
index 00000000000..fc54c0ee1dd
--- /dev/null
+++ b/source/blender/gpu/opengl/gl_query.hh
@@ -0,0 +1,69 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Copyright 2020, Blender Foundation.
+ * All rights reserved.
+ */
+
+/** \file
+ * \ingroup gpu
+ */
+
+#pragma once
+
+#include "BLI_vector.hh"
+
+#include "gpu_query.hh"
+
+#include "glew-mx.h"
+
+namespace blender::gpu {
+
+class GLQueryPool : public QueryPool {
+ private:
+  /** Contains queries object handles. */
+  Vector<GLuint> query_ids_;
+  /** Type of this query pool. */
+  GPUQueryType type_;
+  /** Associated GL type. */
+  GLenum gl_type_;
+  /** Number of queries that have been issued since last initialization.
+   * Should be equal to query_ids_.size(). */
+  uint32_t query_issued_;
+  /** Can only be initialized once. */
+  bool initialized_ = false;
+
+ public:
+  ~GLQueryPool();
+
+  void init(GPUQueryType type) override;
+
+  void begin_query(void) override;
+  void end_query(void) override;
+
+  void get_occlusion_result(MutableSpan<uint32_t> r_values) override;
+};
+
+static inline GLenum to_gl(GPUQueryType type)
+{
+  if (type == GPU_QUERY_OCCLUSION) {
+    /* TODO(fclem) try with GL_ANY_SAMPLES_PASSED​. */
+    return GL_SAMPLES_PASSED;
+  }
+  BLI_assert(0);
+  return GL_SAMPLES_PASSED;
+}
+
+}  // namespace blender::gpu
\ No newline at end of file