By-Movement tile drawing.

gistfile1.cs

...

        private void RenderTiles(GameTime gameTime)
        {
            // Calculate which tiles to draw
            var startX = (Int32)Math.Floor((Single)this.renderArea.Left / TileWorX.TILE_PIXEL_SIZE) - 1;
            var endX = (Int32)Math.Ceiling((Single)this.renderArea.Right / TileWorX.TILE_PIXEL_SIZE) + 1;
            var startY = (Int32)Math.Floor((Single)this.renderArea.Top / TileWorX.TILE_PIXEL_SIZE) - 1;
            var endY = (Int32)Math.Ceiling((Single)this.renderArea.Bottom / TileWorX.TILE_PIXEL_SIZE) + 1;
            var changeX = startX - this.lastStartX;
            var changeY = startY - this.lastStartY;

            if (this.invalidateAll)
            {
                this.GraphicsDevice.SetRenderTarget(this.tileTarget);
                this.GraphicsDevice.Clear(new Color(0x64, 0x95, 0xed, 0xff));
                this.spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, null, null, null);

                // Draw all tiles
                for (var x = startX; x < endX; x += 1)
                {
                    for (var y = startY; y < endY; y += 1)
                    {
                        this.DrawTile(this.Realm.GetTile(x, y), x, y, new Vector2((x - startX) * TileWorX.TILE_PIXEL_SIZE, (y - startY) * TileWorX.TILE_PIXEL_SIZE), Color.White);
                    }
                }

                this.spriteBatch.End();
                this.GraphicsDevice.SetRenderTarget(null);

                this.invalidateAll = false;
            }
            else if (changeX != 0 || changeY != 0)
            {
                this.SwapTileRenderTargets();

                this.GraphicsDevice.SetRenderTarget(this.tileTarget);
                this.GraphicsDevice.Clear(new Color(0x64, 0x95, 0xed, 0xff));
                this.spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, null, null, null);

                this.spriteBatch.Draw(this.oldTileTarget, new Vector2(-changeX * TileWorX.TILE_PIXEL_SIZE, -changeY * TileWorX.TILE_PIXEL_SIZE), Color.White);

                foreach (var p in this.InvalidatedTiles)
                {
                    this.DrawTile(this.Realm.GetTile(p.X, p.Y), p.X, p.Y, new Vector2((p.X - startX) * TileWorX.TILE_PIXEL_SIZE, (p.Y - startY) * TileWorX.TILE_PIXEL_SIZE), Color.White);
                }

                // Draw the new tiles
                if (changeX != 0) // Check if we moved on the x axis
                {
                    if (changeX > 0) // Check if we moved right
                    {
                        Debug.WriteLine("right: " + changeX);
                        var from = endX - changeX;
                        var to = endX;
                        Debug.WriteLine("from: " + from);
                        Debug.WriteLine("to: " + to);

                        for (var x = endX - changeX; x < endX; x += 1)
                        {
                            Debug.WriteLine("right: " + x);
                            for (var y = startY; y < endY; y += 1)
                            {
                                this.DrawTile(this.Realm.GetTile(x, y), x, y, new Vector2((x - startX) * TileWorX.TILE_PIXEL_SIZE, (y - startY) * TileWorX.TILE_PIXEL_SIZE), Color.White);
                            }
                        }
                    }
                    else // Else we moved left
                    {
                        Debug.WriteLine("left: " + changeX);
                        var from = startX;
                        var to = startX - changeX;
                        Debug.WriteLine("from: " + from);
                        Debug.WriteLine("to: " + to);

                        for (var x = startX; x < startX - changeX; x += 1)
                        {
                            Debug.WriteLine("left: " + x);
                            for (var y = startY; y < endY; y += 1)
                            {
                                this.DrawTile(this.Realm.GetTile(x, y), x, y, new Vector2((x - startX) * TileWorX.TILE_PIXEL_SIZE, (y - startY) * TileWorX.TILE_PIXEL_SIZE), Color.White);
                            }
                        }
                    }
                }

                if (changeY != 0) // Check if we moved on the y axis
                {
                    if (changeY > 0) // Check if we moved down
                    {
                        for (var y = endY - changeY; y < endY; y += 1)
                        {
                            for (var x = startX; x < endX; x += 1)
                            {
                                this.DrawTile(this.Realm.GetTile(x, y), x, y, new Vector2((x - startX) * TileWorX.TILE_PIXEL_SIZE, (y - startY) * TileWorX.TILE_PIXEL_SIZE), Color.White);
                            }
                        }
                    }
                    else // Else we moved up
                    {
                        for (var y = startY; y < startY - changeY; y += 1)
                        {
                            for (var x = startX; x < endX; x += 1)
                            {
                                this.DrawTile(this.Realm.GetTile(x, y), x, y, new Vector2((x - startX) * TileWorX.TILE_PIXEL_SIZE, (y - startY) * TileWorX.TILE_PIXEL_SIZE), Color.White);
                            }
                        }
                    }
                }

                this.spriteBatch.End();
                this.GraphicsDevice.SetRenderTarget(null);
            }

            if (this.InvalidatedTiles.Count > 0)
            {
                this.SwapTileRenderTargets();

                this.Game.GraphicsDevice.SetRenderTarget(this.tileTarget);
                this.GraphicsDevice.Clear(new Color(0x64, 0x95, 0xed, 0xff));
                this.spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, null, null, null);

                this.spriteBatch.Draw(this.oldTileTarget, Vector2.Zero, Color.White);

                foreach (var p in this.InvalidatedTiles)
                {
                    this.DrawTile(this.Realm.GetTile(p.X, p.Y), p.X, p.Y, new Vector2((p.X - startX) * TileWorX.TILE_PIXEL_SIZE, (p.Y - startY) * TileWorX.TILE_PIXEL_SIZE), Color.White);
                }

                this.spriteBatch.End();

                this.GraphicsDevice.SetRenderTarget(null);
            }

            this.lastStartX = startX;
            this.lastStartY = startY;
        }
    }
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