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/gl/draw.cc | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 src/gl/draw.cc

(limited to 'src/gl/draw.cc')

diff --git a/src/gl/draw.cc b/src/gl/draw.cc
new file mode 100644
index 0000000..9d20fe1
--- /dev/null
+++ b/src/gl/draw.cc
@@ -0,0 +1,56 @@
+// 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.
+
+#include "src/gl/draw.h"
+
+#include <assert.h>
+
+#include "src/gl/error.h"
+#include "src/gl/vertex_array.h"
+#include "src/util.h"
+#include "third_party/glew/include/GL/glew.h"
+
+namespace gl {
+
+void DrawElements(const gl::VertexArray& vao, Primitive mode) {
+  gl_internal::CheckThreadSafety();
+
+  GLenum type;
+  switch (vao.element_buffer().element_size()) {
+    case 1:
+      type = GL_UNSIGNED_BYTE;
+      break;
+    case 2:
+      type = GL_UNSIGNED_SHORT;
+      break;
+    case 4:
+      type = GL_UNSIGNED_INT;
+      break;
+    default:
+      assert(false);
+  };
+
+  glDrawElements(FromEnum(mode), vao.element_buffer().size(), type,
+                 /*indices=*/0);
+  // This error check is necessary because the mode could be unsupported.
+  gl_internal::ErrorCheck();
+}
+
+void SetViewport(int x, int y, int width, int height) {
+  gl_internal::CheckThreadSafety();
+  glViewport(x, y, width, height);
+  gl_internal::ErrorCheck();
+}
+
+}  // namespace gl
-- 
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