crystal.DrawEffect

A Component that can affect how drawables on this entity are drawn.

DrawSystem surrounds each Drawable:draw() with calls to pre_draw() and post_draw() on entities’ DrawEffect components. The order in which the draw effects are applied for each Drawable component is unspecified.

This class is only useful when overriding pre_draw() and/or post_draw(), as the default implementations are blank. An example usage of this component would be to use pre_draw() to call love.graphics.setShader, in order to apply a visual effect to an entity.

Constructor

Like all other components, DrawEffect components are created by calling Entity:add_component.

The constructor for DrawEffect expects no arguments.

Methods

Name	Description
post_draw	Method called before drawing Drawable components on this entity. Base implementation is empty.
pre_draw	Method called after drawing Drawable components on this entity. Base implementation is empty.

Examples

This example defines a component which offsets entities vertically to simulate altitude in a top-down 2D game.

local Altitude = Class("Altitude", crystal.DrawEffect);

Altitude.init = function(self, altitude)
  self.altitude = altitude;
end

Altitude.pre_draw = function(self)
  love.graphics.translate(0, -self.altitude);
end