Sohail Mehra – Spark AR Scripting - Ep 3 – Updated for Spark AR Studio v102

script.js

const S = require('Shaders');
const M = require('Materials');
const T = require('Textures');
const R = require('Reactive');

const Time = require('Time');

async function main()
{
    // CPU code

    const defaultMat = await M.findFirst('material0'); // const defaultMat = M.get('material0'); // before v85 
    const cameraTex = await T.findFirst('cameraTexture0'); // const cameraTex = T.get('cameraTexture0'); // before v85
    
    const seconds = R.mul(Time.ms,0.001);
    const curve = R.abs(R.sin(seconds));
    const uv_curve = R.mul(R.sin(seconds),0.1);

    // Vertex Shader 

    const uv = S.vertexAttribute({"variableName" : S.VertexAttribute.TEX_COORDS});
    
    // Interpolators
    // uv (vertex shader) -> uv (fragment shader)

    const fuv = S.fragmentStage(uv);
    
    // Fragment Shader (Pixel Shader)

    const color = S.textureSampler( cameraTex.signal, uv );
    const left_color = R.add(color,R.pack4(curve,0,0,1));
    const right_color = R.add(color,R.pack4(0,0,curve,1));
 
    const anim_uv = R.add(fuv,uv_curve);
    const split = R.step(anim_uv.x, 0.5); // x < 0.5 ? 0 : 1
    const ss = R.smoothStep(anim_uv.x,0.3,0.6);
    const uv_color = R.pack4(ss,ss,ss,1);

    // mix (lerp)
    // a,b,t [0,1]
        // 0 -> a * 1 + b * 0
        // a
        // 1 -> a * 0 + b * 1
        // b
        // 0.5 -> a * 0.5 + b * 0.5

    const blend_color = R.mix(left_color,right_color,ss);
    const final_color = blend_color;

    const textureSlot = S.DefaultMaterialTextures.DIFFUSE;
    defaultMat.setTextureSlot(textureSlot, final_color); 
}
main();