const renderEngine = cc.renderer.renderEngine;
const renderer = renderEngine.renderer;
let ShaderMaterial = require('ShaderMaterial');

const shader = {
    name: 'Grass',
    params: [
        { name: 'u_cPos', type: renderer.PARAM_FLOAT2 },
        // { name: 'u_mPos', type: renderer.PARAM_FLOAT2 },
        // { name: 'u_width', type: renderer.PARAM_FLOAT },
        // { name: 'u_height', type: renderer.PARAM_FLOAT },
        { name: 'u_dis', type: renderer.PARAM_FLOAT },
        { name: 'u_plus', type: renderer.PARAM_FLOAT },
    ],

    start(material,params) {
        material.setParamValue('u_cPos', cc.v2(0,0));
        material.setParamValue('u_dis', params.distance);
        material.setParamValue('u_plus', params.plus);

        // material.setParamValue('u_mPos', cc.v2(params.pos.x,params.pos.y));//
        // material.setParamValue('u_width', params.width);
        // material.setParamValue('u_height', params.height);
     
    },

   

    defines:[],


    frag:
        `uniform sampler2D texture;
        uniform vec4 color;
        varying vec2 uv0;

        varying vec2 uv1;
        varying vec2 uv2;
        varying vec2 uv3;

        uniform vec2  u_cPos;
        uniform float u_dis;
        uniform float u_plus;

        void main()
        {

            vec4 src_color =  texture2D(texture, uv0).rgba;
         
            vec2 rpos = vec2(uv2.x + uv3.x*uv1.x , uv2.y + uv3.y*uv1.y );
            float dis = distance(rpos,u_cPos);
            if(dis<u_dis){


        
             
                float mask = smoothstep(0.8, 0.9, dis/u_dis);
                if(mask < u_plus){
                    mask = u_plus;
                }
                src_color.a = src_color.a*mask;
              
               
                // src_color += vec4(0.2,0.2,0.2,0.0);
            }


            gl_FragColor = src_color;
        }`,
};

ShaderMaterial.addShader(shader);