Passing second texture to GLSL shader

Charcoal

I'm jumping into some shader dev in HaxeFlixel and one thing I want to do is a multiplication filter.

Right now I have this shader code:

#pragma header
uniform sampler2D tex;

void main()
{
	vec4 source= flixel_texture2D(tex, openfl_TextureCoordv);
	vec4 other= texture2D(tex, openfl_TextureCoordv);
	gl_FragColor = vec4(source.r * other.r, source.g * other.g, source.b * other.b, source.a);
}

And am using the shader this way:

	var mul = new MultiplyShader();
	var si = new ShaderInput<BitmapData>();
	var fs = new FlxSprite(0,0, "assets/images/quads.png");
	si.input = fs.pixels.clone();

	mul.tex = si;
	FlxG.camera.setFilters([new ShaderFilter(cast inv)]);

Testing other things (like mapping the openfl_TextureCoordv to r/g) works, but I can't access anything from the passed in texture.

Charcoal

Seems my problem is partially a little bug with the current release version of OpenFL:
http://community.openfl.org/t/sampling-second-texture-in-glsl-shader/10628

Using the GIT develop version allows it to work on flixel sprites.
But, I can't get a shader that samples a second texture to work in the FlxCamera's shaders.