Shader stealing porting 101

1. Adding this to FNF:

(THIS MIGHT BREAK ANY SHADERS YOU USED BEFORE)

• Copy the source and assets folder to your fnf source folder.

• Add this in your Paths.hx

inline static public function shaderFragment(key:String, ?library:String)
{
	return getPath('shaders/$key.frag', TEXT, library);
}

• Add these to your PlayState.hx

  • At the start:

import DynamicShaderHandler;

• In the variables:

public static var animatedShaders:Map<String, DynamicShaderHandler> = new Map<String, DynamicShaderHandler>();

• In update function:

for (shader in animatedShaders)
{
	shader.update(elapsed);
}

• In update function (if Lua is used):

#if #FEATURE_LUAMODCHART
for (key => value in luaModchart.luaShaders)
{
	value.update(elapsed);
}
#end

• Add these to your ModchartState.hx for Lua support (KE / KE forks only)

  • In the variables:

public var luaShaders:Map<String, DynamicShaderHandler> = new Map<String, DynamicShaderHandler>();
public var camTarget:FlxCamera;

• As Lua callbacks:

import openfl.filters.BitmapFilter;

Lua_helper.add_callback(lua, "createShaders", function(shaderName, ?optimize:Bool = false)
{
	var shader = new DynamicShaderHandler(shaderName, optimize);

	return shaderName;
});

Lua_helper.add_callback(lua, "modifyShaderProperty", function(shaderName, propertyName, value)
{
	var handler = luaShaders[shaderName];
	handler.modifyShaderProperty(propertyName, value);
});

// shader set

Lua_helper.add_callback(lua, "setShadersToCamera", function(shaderName:Array<String>, cameraName)
{
	switch (cameraName)
	{
		case 'hud':
			camTarget = PlayState.instance.camHUD;
		case 'notes':
			camTarget = PlayState.instance.camNotes;
		case 'sustains':
			camTarget = PlayState.instance.camSustains;
		case 'game':
			camTarget = FlxG.camera;
	}

	var shaderArray = new Array<BitmapFilter>();

	for (i in shaderName)
	{
		shaderArray.push(new ShaderFilter(luaShaders[i].shader));
	}

	camTarget.setFilters(shaderArray);
});

// shader clear

Lua_helper.add_callback(lua, "clearShadersFromCamera", function(cameraName)
{
	switch (cameraName)
	{
		case 'hud':
			camTarget = PlayState.instance.camHUD;
		case 'notes':
			camTarget = PlayState.instance.camNotes;
		case 'sustains':
			camTarget = PlayState.instance.camSustains;
		case 'game':
			camTarget = FlxG.camera;
	}
	camTarget.setFilters([]);
});

---

2. Porting Shaders from shadertoy:

(PLEASE MAKE SURE TO READ THE LICENSE OF THE SHADER YOU ARE PORTING)

• First of all, you need to know that shadertoy automatically uses the inputs below:

uniform vec3      iResolution;           // viewport resolution (in pixels)
uniform float     iTime;                 // shader playback time (in seconds)
uniform float     iTimeDelta;            // render time (in seconds)
uniform int       iFrame;                // shader playback frame
uniform float     iChannelTime[4];       // channel playback time (in seconds)
uniform vec3      iChannelResolution[4]; // channel resolution (in pixels)
uniform vec4      iMouse;                // mouse pixel coords. xy: current (if MLB down), zw: click
uniform samplerXX iChannel0..3;          // input channel. XX = 2D/Cube
uniform vec4      iDate;                 // (year, month, day, time in seconds)
uniform float     iSampleRate;           // sound sample rate (i.e., 44100)

Currently, my implementation only supports the following inputs: (iResolution, iTime, iChannel0).

Support for iMouse input is planned for the future.

• For this instance we will be porting https://www.shadertoy.com/view/lddXWS

The shader code is the following:

const float RADIUS	= 100.0;
const float BLUR	= 200.0;
const float SPEED   = 2.0;
void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
    vec2 uv = fragCoord.xy / iResolution.xy;
    vec4 pic = texture(iChannel0, vec2(uv.x, uv.y));
    
    vec2 center = iResolution.xy / 2.0;
    float d = distance(fragCoord.xy, center);
    float intensity = max((d - RADIUS) / (2.0 + BLUR * (1.0 + sin(iTime*SPEED))), 0.0);
    
    fragColor = vec4(intensity + pic.r, intensity + pic.g, intensity + pic.b, 1.0);
}

We need to modify some stuff,

• main function header void mainImage( out vec4 fragColor, in vec2 fragCoord ) should be changed to void main() and add this new line at the start of function: vec2 fragCoord = openfl_TextureCoordv * iResolution;

• The shader outputs to fragColor, this should be changed to gl_FragColor

• at the very start of the shader add those two uniforms: uniform vec2 iResolution; uniform float iTime;

• if your shader makes use of iChannel0 sampler, change that to bitmap, other channels are not supported (unless replacing them all with bitmap still serves your purpose, use common sense)

• if your shader outputs alpha pixels and they're black (Black instead of transparent), Make sure to use\change texture function to texture2D instead of texture

• The final result should be like this:

    uniform vec2 iResolution;
    uniform float iTime;

    const float RADIUS	= 200.0;
    const float BLUR	= 500.0;
    const float SPEED   = 2.0;

    void main()
    {
        vec2 fragCoord = openfl_TextureCoordv * iResolution;

        vec2 uv = fragCoord.xy / iResolution.xy;
        vec4 pic = texture2D(bitmap, vec2(uv.x, uv.y));
        
        vec2 center = iResolution.xy / 2.0;
        float d = distance(fragCoord.xy, center);
        float intensity = max((d - RADIUS) / (2.0 + BLUR * (1.0 + sin(iTime*SPEED))), 0.0);

        gl_FragColor = vec4(intensity + pic.r, intensity + pic.g, intensity + pic.b, 0.2);
    }

---

3. Usage through Haxe:

• Shaders should be placed in /shaders folder, with .frag extension, See shaders folder for more examples.
• Params are the file name and optimize bool, this might help with heavy shaders but only makes a difference on decent Intel CPUs (ones with SSE Instructions support).

new DynamicShaderHandler("Example");
FlxG.camera.setFilters([new ShaderFilter(animatedShaders["Example"].shader)]);

or

var spr:FlxSprite = new ShaderSprite("Example");

---

4. Usage through Lua:

• You can initialize shaders through Lua using this function (parameters are shader name and optimize (optional))

createShaders("Example",true)

• You can load shaders onto cameras using this function (parameters are array of shader names and camera)

setShadersToCamera({"Example"},camera)

• You can clear shader filters using this function (parameters are camera name):

clearShadersFromCamera(camera)

• And you can modify shader uniforms with this method (parameters are shader name, property and value):

modifyShaderProperty("Example","Property",Value)

• Valid cameras are "game", "hud", "notes" and "sustains".

---

Credits:

• SqirraRNG: Runtime shaders workaround.

• Kemo (me): Handler, Improvements, Guide.

• Fireable: Lua implementation

  • If you are going to port this to any engine, please make sure to leave a noticable credit and respect the effort, this was planned to be nexus engine exclusive but there ya :).

  • If you run into any issues (that aren't common sense), feel free to DM me on discord kemo#1337.