Radegast.Rendering.SceneWindow.TryPick C# (CSharp) Method

        public bool TryPick(int x, int y, out object picked, out int faceID, out Vector3 worldPos)
        {
            // Save old attributes
            GL.PushAttrib(AttribMask.AllAttribBits);

            // Disable some attributes to make the objects flat / solid color when they are drawn
            GL.Disable(EnableCap.Fog);
            GL.Disable(EnableCap.Texture2D);
            GL.Disable(EnableCap.Dither);
            GL.Disable(EnableCap.Lighting);
            GL.Disable(EnableCap.LineStipple);
            GL.Disable(EnableCap.PolygonStipple);
            GL.Disable(EnableCap.CullFace);
            GL.Disable(EnableCap.Blend);
            GL.Disable(EnableCap.AlphaTest);

            Render(true);

            byte[] color = new byte[4];
            GL.ReadPixels(x, glControl.Height - y, 1, 1, OpenTK.Graphics.OpenGL.PixelFormat.Rgba, PixelType.UnsignedByte, color);
            float depth = 0f;
            GL.ReadPixels(x, glControl.Height - y, 1, 1, OpenTK.Graphics.OpenGL.PixelFormat.DepthComponent, PixelType.Float, ref depth);
            OpenTK.Vector3 worldPosTK = OpenTK.Vector3.Zero;
            Math3D.GluUnProject(x, glControl.Height - y, depth, ModelMatrix, ProjectionMatrix, Viewport, out worldPosTK);
            worldPos = RHelp.OMVVector3(worldPosTK);
            GL.PopAttrib();

            int primID = Utils.BytesToUInt16(color, 0);
            faceID = color[2];

            picked = null;

            if (color[3] == 253) // Terrain
            {
                int vertexIndex = Utils.BytesToInt(new byte[] { color[0], color[1], color[2], 0 });
                ColorVertex cv;
                if (terrain.TryGetVertex(vertexIndex, out cv))
                {
                    picked = cv.Vertex.Position;
                    return true;
                }
            }
            else if (color[3] == 254) // Avatar
            {
                lock (VisibleAvatars)
                {
                    foreach (var avatar in VisibleAvatars)
                    {
                        for (int i = 0; i < avatar.data.Length; i++)
                        {
                            var face = avatar.data[i];
                            if (face != null && face.PickingID == primID)
                            {
                                picked = avatar;
                                break;
                            }
                        }
                    }
                }

                if (picked != null)
                {
                    return true;
                }
            }
            else if (color[3] == 255) // Prim
            {
                lock (SortedObjects)
                {
                    foreach (SceneObject obj in SortedObjects)
                    {
                        if (!(obj is RenderPrimitive)) continue;
                        RenderPrimitive prim = (RenderPrimitive)obj;

                        if (obj.BasePrim.LocalID == 0)
                            continue;

                        foreach (var face in prim.Faces)
                        {
                            if (face.UserData == null) continue;
                            if (((FaceData)face.UserData).PickingID == primID)
                            {
                                picked = prim;
                                break;
                            }
                        }

                        if (picked != null) break;
                    }
                }
            }

            return picked != null;
        }