public override void Draw(SpriteBatch spriteBatch, Rectangle? visibleRectangle = null, Color? backgroundColor = null)
{
if(!IsVisible)
return;
if (_renderTarget == null)
{
// create and render the entire map to a single render target.
// this gives the best frame rate performance at the cost of memory.
// ideally, we'd like to have a couple of different draw strategies for different situations.
_renderTarget = new RenderTarget2D(_renderTargetSpriteBatch.GraphicsDevice, _map.WidthInPixels, _map.WidthInPixels);
using (_renderTarget.BeginDraw(_renderTargetSpriteBatch.GraphicsDevice, backgroundColor ?? Color.Transparent))
{
//var vr = visibleRectangle ?? new Rectangle(0, 0, _map.WidthInPixels, _map.HeightInPixels);
var vr = new Rectangle(0, 0, _map.WidthInPixels, _map.HeightInPixels);
var renderOrderFunction = GetRenderOrderFunction();
var tileLocationFunction = GetTileLocationFunction();
var firstCol = vr.Left < 0 ? 0 : (int) Math.Floor(vr.Left/(float) _map.TileWidth);
var firstRow = vr.Top < 0 ? 0 : (int) Math.Floor(vr.Top/(float) _map.TileHeight);
// +3 to cover any gaps
var columns = Math.Min(_map.Width, vr.Width/_map.TileWidth) + 3;
var rows = Math.Min(_map.Height, vr.Height/_map.TileHeight) + 3;
_renderTargetSpriteBatch.Begin(blendState: BlendState.AlphaBlend, samplerState: SamplerState.PointClamp);
foreach (var tile in renderOrderFunction(firstCol, firstRow, firstCol + columns, firstRow + rows))
{
var region = tile != null ? _map.GetTileRegion(tile.Id) : null;
if (region != null)
{
var point = tileLocationFunction(tile);
var destinationRectangle = new Rectangle(point.X, point.Y, region.Width, region.Height);
_renderTargetSpriteBatch.Draw(region, destinationRectangle, Color.White*Opacity);
}
}
_renderTargetSpriteBatch.End();
}
}
spriteBatch.Draw(_renderTarget, Vector2.Zero, Color.White);
}
