SpriteLight rendering is a simple 2d light rendering technique where sprites are used to form a lightmap. This lightmap is then used to illuminate the scene.

info

The assets from this example can be downloaded here.

Sample

We start by setting up the render layers

public const int SpriteLightRenderLayer = 1;

public const int BackgroundRenderLayer = 2;

Next, we add a renderer for the drawables in our scene.

AddRenderer(new RenderLayerRenderer(0, BackgroundRenderLayer));

Next, we create a renderer for our light map. We assign a RenderTexture to which the light map will be rendered.

RenderTargetClearColor is used to create a slight ambient color. If you have a scene that is reasonably lit, you could use, for example, new Color(100, 100, 100, 255);

RenderLayerRenderer lightRenderer = AddRenderer(new RenderLayerRenderer(-1, SpriteLightRenderLayer));

lightRenderer.RenderTexture = new RenderTexture();

lightRenderer.RenderTargetClearColor = new Color(10, 10, 10, 255);

Next, we add our background, which we render to BackgroundRenderLayer.

var bgTexture = Content.Load<Texture2D>("background");

var bgEntity = CreateEntity("bg");

bgEntity.Position = Screen.Center;

bgEntity.Scale = new Vector2(9.4f);

var bgSprite = bgEntity.AddComponent(new SpriteRenderer(bgTexture));

bgSprite.RenderLayer = BackgroundRenderLayer;

Next we add our light, which we render to SpriteLightRenderLayer.

var lightTexture = Content.Load<Texture2D>("spritelight");

var lightEntity = CreateEntity("light");

lightEntity.Position = new Vector2(Screen.Width / 2f, Screen.Height / 2f);

lightEntity.Scale = new Vector2(4);

var lightSprite = lightEntity.AddComponent(new SpriteRenderer(lightTexture));

lightSprite.RenderLayer = SpriteLightRenderLayer;

And finally we add the SpriteLightPostProcessor, which renders the scene using the lightmap RenderTexture.

AddPostProcessor(new SpriteLightPostProcessor(0, lightRenderer.RenderTexture));