const renderEngine = cc.renderer.renderEngine;
const renderer = renderEngine.renderer;
let ShaderMaterial = require('ShaderMaterial');
var timelimit =1
const shader = {
    name: 'Wave',
    params: [
        { name: 'time', type: renderer.PARAM_FLOAT },
        { name: 'u_normalMap', type: renderer.PARAM_TEXTURE_2D },
    ],

    start(material,params) {
         material.cusparmas = {}
         material.cusparmas._start = 0;
         material.setParamValue('u_normalMap', params.normaltexture._texture);//偏移值         (调整该值改变流光的倾斜程度)

    },

    update(material,dt) {
        material.cusparmas._start+=dt*0.2
        //var deltatime = Math.sin(( material.cusparmas._start)/1000);
        material.setParamValue('time',Math.sin(material.cusparmas._start)*2);
    },

    defines:[],

    frag:
        `varying vec4 v_fragmentColor;
        varying vec2 uv0;
        uniform sampler2D texture;
        uniform sampler2D u_normalMap;
        uniform float time;
        vec3 waveNormal(vec2 p) { 
            vec3 normal = texture2D(u_normalMap , p ).xyz;  
            normal = -1.0 + normal * 2.0;  
            return normalize(normal);  
        }  
         
         
        //高光计算 参见基本光照公式
        //参数说明：n法向量， l入射光向量， e观察向量
        float specular(vec3 n,vec3 l,vec3 e) {    
            return pow(max(dot(reflect(e,n),l),0.0),2.0); 
        }
           
        void main() {  
         
            float timeFactor = 0.1;
            float offsetFactor = 0.5;
            float refractionFactor = 0.7;
            // simple UV animation
            vec3 normal = waveNormal(uv0 + vec2(time * timeFactor,time * timeFactor));
         
            // simple calculate refraction UV offset
            vec2 p = -1.0 + 2.0 * uv0; 
            vec3 eyePos = vec3(0.0, 0.0, 10.0);//眼睛的位置 在中心点正上方
         
            vec3 inVec = normalize(vec3(p, 0.0) - eyePos);
            vec3 refractVec = refract(inVec, normal, refractionFactor);
            vec2 v_texCoordN = uv0;
            v_texCoordN += refractVec.xy * offsetFactor;
             
            vec3 light = vec3(0.2,0.1,0.0);    
            // bteitler: Apply specular highlight
            vec3 normalN = waveNormal(v_texCoordN );
            vec3 color = vec3(specular(normalN,light,eyePos));
         
            //gl_FragColor = texture2D(texture, v_texCoordN); //这样可以看到不带高光的水面，可选
            // gl_FragColor = texture2D(u_normalMap, uv0); //这样可以只看法线图，可选
            gl_FragColor = texture2D(texture, v_texCoordN)*1.0 + vec4(color,1); //加了高光效果的水面
        }  
`,
};

ShaderMaterial.addShader(shader);