render little thumbnails for each loaded image

Program.cs

@@ -221,18 +221,18 @@ public class Game : GameWindow {
   protected override void OnLoad() {
     base.OnLoad();
 
-    GL.ClearColor(0.2f, 0.3f, 0.3f, 1.0f);
+    GL.ClearColor(0.0f, 0.0f, 0.05f, 1.0f);
 
     VertexArrayObject = GL.GenVertexArray();
     GL.BindVertexArray(VertexArrayObject);
 
     VertexBufferObject = GL.GenBuffer();
-    GL.BindBuffer(BufferTarget.ArrayBuffer, VertexBufferObject);
-    GL.BufferData(BufferTarget.ArrayBuffer, vertices.Length * sizeof(float), vertices, BufferUsageHint.StaticDraw);
-
     ElementBufferObject = GL.GenBuffer();
+
+    GL.BindBuffer(BufferTarget.ArrayBuffer, VertexBufferObject);
+    GL.BufferData(BufferTarget.ArrayBuffer, vertices.Length * sizeof(float), vertices, BufferUsageHint.DynamicDraw);
     GL.BindBuffer(BufferTarget.ElementArrayBuffer, ElementBufferObject);
-    GL.BufferData(BufferTarget.ElementArrayBuffer, indices.Length * sizeof(uint), indices, BufferUsageHint.StaticDraw);
+    GL.BufferData(BufferTarget.ElementArrayBuffer, indices.Length * sizeof(uint), indices, BufferUsageHint.DynamicDraw);
 
     shader = new Shader();
     shader.Use();
@@ -257,7 +257,7 @@ public class Game : GameWindow {
     foreach (string file in files) {
       if (file.ToLower().EndsWith(".jpg")) {
         textures.Add(new Texture(file));
-      }      
+      }
     }
   }
 
@@ -269,11 +269,25 @@ public class Game : GameWindow {
     base.OnRenderFrame(e);
     frameCount++;
     GL.Clear(ClearBufferMask.ColorBufferBit);
-    GL.BindVertexArray(VertexArrayObject);
+
+    SetVertices(0, 0, windowWidth - 152, windowHeight);
+    GL.BindBuffer(BufferTarget.ArrayBuffer, VertexBufferObject);
+    GL.BufferData(BufferTarget.ArrayBuffer, vertices.Length * sizeof(float), vertices, BufferUsageHint.DynamicDraw);
     GL.ActiveTexture(TextureUnit.Texture0);
     GL.BindTexture(TextureTarget.Texture2D, textures[textureIndex].Handle);
     shader.Use();
     GL.DrawElements(PrimitiveType.Triangles, indices.Length, DrawElementsType.UnsignedInt, 0);
+
+    for (int i = 0; i < textures.Count; i++) {
+      SetVertices(windowWidth - 150, i * 100, windowWidth, i * 100 + 98);
+      GL.BindBuffer(BufferTarget.ArrayBuffer, VertexBufferObject);
+      GL.BufferData(BufferTarget.ArrayBuffer, vertices.Length * sizeof(float), vertices, BufferUsageHint.DynamicDraw);
+      GL.ActiveTexture(TextureUnit.Texture0);
+      GL.BindTexture(TextureTarget.Texture2D, textures[i].Handle);
+      shader.Use();
+      GL.DrawElements(PrimitiveType.Triangles, indices.Length, DrawElementsType.UnsignedInt, 0);
+    }
+
     SwapBuffers();
   }
 
@@ -287,6 +301,36 @@ public class Game : GameWindow {
     GL.UniformMatrix4(shader.GetUniformLocation("projection"), true, ref projection);
     GL.Viewport(0, 0, windowWidth, windowHeight);
   }
+
+  private void SetVertices(float left, float top, float right, float bottom) {
+    // top left
+    vertices[0] = left;
+    vertices[1] = top;
+    vertices[2] = 0f;
+    vertices[3] = 0f;
+    vertices[4] = 0f;
+
+    // top right
+    vertices[5] = right;
+    vertices[6] = top;
+    vertices[7] = 0f;
+    vertices[8] = 1f;
+    vertices[9] = 0f;
+
+    // bottom right
+    vertices[10] = right;
+    vertices[11] = bottom;
+    vertices[12] = 0f;
+    vertices[13] = 1f;
+    vertices[14] = 1f;
+
+    // bottom left
+    vertices[15] = left;
+    vertices[16] = bottom;
+    vertices[17] = 0f;
+    vertices[18] = 0f;
+    vertices[19] = 1f;
+  }
 }
 
 static class Program {