Filters.md

Filters

Filters apply to the display tree, so can be used to create screen effects. You can assign a filter to a h2d.Sprite.

mySprite.filter = new Glow();

Build-in filters

Heaps provides several filters like Ambient, Bloom, Blur, ColorMatrix, Displacement, DropShadow, Glob, Mask. They can be found in the h2d.filter package.

Creating custom screen shader filters

To create a shader that works as filter, you need a screen shader.

As you can see in h3d.shader.ScreenShader, screen shaders only provides you input.position and input.uv, and you can alter the output.position or output.color.

@input var input : {
	position : Vec2,
	uv : Vec2,
};
var output : {
	position : Vec4,
	color : Vec4,
};

Let's create a simple shader that changes the red channel based on a parameter:

class MyFilterShader extends h3d.shader.ScreenShader {
	static var SRC = {
		@param var texture : Sampler2D;
		@param var red : Float;

		function fragment() {
			pixelColor = texture.get(input.uv);
			pixelColor.r = red; // change red channel
		}
	}
}

Usage:

var myShader = new MyFilterShader();
myShader.red = 1; // use 0-1 range
var customFilter = new h2d.filter.Shader(myShader);
mySprite.filter = customFilter;

Multiple filters on one sprite

To apply multiple filters, use h2d.filter.Group.

var group = new Group([filter1, filter2]);
mySprite.filter = group;