From d0e18bdb7924c71cdca8dd983711171d87ef28be Mon Sep 17 00:00:00 2001
From: Benjamin Barenblat <bbarenblat@gmail.com>
Date: Mon, 17 Jan 2022 23:12:32 -0500
Subject: glplanet, an OpenGL-based planetary renderer
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glplanet draws Earth like it currently appears from space, putting
nighttime areas in shadow and daytime areas in light. It’s modeled
after Xplanet (http://xplanet.sourceforge.net/), but whereas Xplanet is
entirely a CPU-resident program, glplanet draws using OpenGL. It’s thus
much less resource-intensive, particularly when using high-resolution
textures.
---
 src/scene.h | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100644 src/scene.h

(limited to 'src/scene.h')

diff --git a/src/scene.h b/src/scene.h
new file mode 100644
index 0000000..36da1e0
--- /dev/null
+++ b/src/scene.h
@@ -0,0 +1,87 @@
+// Copyright 2021, 2022 Benjamin Barenblat
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not
+// use this file except in compliance with the License. You may obtain a copy of
+// the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations under
+// the License.
+
+#ifndef GLPLANET_SRC_SCENE_H_
+#define GLPLANET_SRC_SCENE_H_
+
+#include <stdint.h>
+
+#include <Eigen/Core>
+#include <chrono>
+
+#include "src/gl/buffer.h"
+#include "src/gl/draw.h"
+#include "src/gl/shader.h"
+#include "src/gl/texture.h"
+#include "src/gl/vertex_array.h"
+#include "third_party/abseil/absl/base/attributes.h"
+#include "third_party/date/include/date/date.h"
+#include "third_party/date/include/date/tz.h"
+
+namespace glplanet {
+
+// The scene to draw.
+//
+// This class hangs onto some OpenGL state, so it is thread-hostile.
+class Scene final {
+ public:
+  struct Options {
+    // The part of the Earth under the camera, in radians east longitude and
+    // north latitude.
+    double longitude_radians;
+    double latitude_radians;
+  };
+
+  // Constructs a scene. There must be an OpenGL context bound to the current
+  // thread.
+  explicit Scene(const Options&);
+
+  Scene(Scene&&) noexcept = default;
+  Scene& operator=(Scene&&) noexcept = default;
+
+  // Sets up OpenGL state (binding buffers etc.) such that the scene can be
+  // drawn.
+  void SetGlState();
+
+  // Actually draws the scene.
+  void Draw(std::chrono::system_clock::time_point);
+
+ private:
+  void LoadTextures();
+  void SetUpShaders();
+  void LoadMesh();
+
+  date::month planet_month_;
+  gl::Texture2d planet_;
+
+  gl::Texture2d clouds_;
+
+  gl::ShaderProgram program_;
+  int uniform_mvp_;
+  int uniform_planet_;
+  int uniform_clouds_;
+  int uniform_sun_direction_;
+
+  Eigen::Matrix4f mvp_;
+
+  gl::VertexArray vao_;
+
+  int width_;
+  int height_;
+  bool window_size_changed_;
+};
+
+}  // namespace glplanet
+
+#endif  // GLPLANET_SRC_SCENE_H_
-- 
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