// import { vertexShader, fragmentShader } from './shaders'
// import Tween from './tween'
import * as THREE from "../../../../libs/three.js/build/three.module.js";
import { vertexShader, fragmentShader } from './shader.js'

let ONE_SPRITE_ROW_LENGTH = 0.25    //对应着色器的0.25
let texture 
 

const getTexture = ()=>{
    if(!texture){
        texture = new THREE.TextureLoader().load( Potree.resourcePath+'/textures/fire.png')
    }
    return texture
}





class FireParticle extends THREE.Points{
  
    constructor (prop) {
        super()
        
        for ( var key in prop ){
            this[key] = prop[key]
        }
        
        
         
        this.density = this.density || 1
        
        
         
        this.fireRadius = prop.fireRadius || 1;
        this.fireHeight = prop.fireHeight || 5;  
        
        this.computeParams()
        this.geometry = this.createGeometry( this.fireRadius, this.fireHeight, this.particleCount );
         
        
        
        this.material = this.createMaterial(  prop.fov, 0xff3200 );  //小蓝火：0x00338f
        
      
         
        //---?:
        this.velocity = new THREE.Vector3()
        this.acceleration = new THREE.Vector3()
        
        this.angle = 0
        this.angleVelocity = 0
        this.angleAcceleration = 0
        this.size = 16
        this.color = new THREE.Color()
        this.opacity = 1

        this.age = 0
        this.alive = 0

        this.sizeTween = null
        this.colorTween = null
        this.opacityTween = null

        
         
        this.setSize({viewport:viewer.mainViewport})
        this.setFov(viewer.fov)
        viewer.addEventListener('resize',(e)=>{ 
            if(e.viewport.name != "MainView")return
            this.setSize(e) 
        })  
        viewer.addEventListener('fov_changed',(e)=>{ 
            this.setFov(e.fov) 
        })  
    }

 
    computeParams(){  
        let length = (this.curve ? this.curve.wholeLength : 0) + this.fireRadius * 2 //加上首尾的半径
        this.particleCount =  Math.ceil( this.fireRadius * this.fireHeight * length * this.density *  5  )        
        console.log('fire particleCount',this.particleCount)
    }

    createGeometry( radius, height, particleCount){
        let geometry = new THREE.BufferGeometry()
        
        
        
        var halfHeight = height * 0.5;
        
        let count , points
        if(this.positions.length>1){
             
            const spaceDis = 0.2;//间隔距离
            
            count = Math.ceil(this.curve.wholeLength / spaceDis) + 1 
            console.log('count', count)
            points = this.curve.getSpacedPoints( count );  //得到的数量会比count多一个
            count = points.length  
            //得到的点不太均匀，两端容易点少。
            
            
        }
         
        
        var position = new Float32Array(particleCount * 3);
        var randam = new Float32Array(particleCount);
        var sprite = new Float32Array(particleCount);
        var centerHeight = new Float32Array(particleCount);
        
        for (var i = 0; i < particleCount; i++) {
            
            var center = new THREE.Vector3().copy(this.positions.length>1 ? points[Math.floor(i/particleCount * count)] : this.positions[0])
            centerHeight[i] = center.z
            
            if (i === 0) { 
                // to avoid going out of Frustum
                position[i * 3 + 0] = center.x;
                position[i * 3 + 1] = center.y;
                position[i * 3 + 2] = center.z;
            }else{  
                var r = Math.sqrt(Math.random()) * radius;
                var angle = Math.random() * 2 * Math.PI;
                position[i * 3 + 0] = center.x + Math.cos(angle) * r; 
                position[i * 3 + 1] = center.y + Math.sin(angle) * r;
                position[i * 3 + 2] = center.z + (radius - r) / radius * halfHeight + halfHeight; //不太明白这句为什么能达到height高度
               
                sprite[i] = 0.25 * (Math.random() * 4 | 0);
                randam[i] = Math.random();
                //center在底部
            }
            
            
        }
        
        geometry.setAttribute('centerHeight', new THREE.BufferAttribute(centerHeight, 1));
        geometry.setAttribute('position', new THREE.BufferAttribute(position, 3));
        geometry.setAttribute('randam', new THREE.BufferAttribute(randam, 1));
        geometry.setAttribute('sprite', new THREE.BufferAttribute(sprite, 1));
        return geometry;
    }
    
    
    
    
    updateGeometry(){ 
        this.computeParams()
        this.geometry.dispose() 
        this.geometry = this.createGeometry( this.fireRadius, this.fireHeight, this.particleCount )
        
    }


    createMaterial(fov, color){
        
        const material = new THREE.ShaderMaterial( {
            uniforms:{
                color: { type: "c", value: new THREE.Color(color) },
                size: { type: "f", value: THREE.Math.clamp(this.fireRadius * 1.2, 0.5, 5)},
                u_sampler: { type: "t", value: getTexture() },
                time: { type: "f", value: 0.0 },
                heightOfNearPlane: { type: "f", value:0},  //相对far ，以确保画面缩放时点的大小也会缩放
                fireHeight :{ type: "f", value:this.fireHeight}  ,
            },
            vertexShader,
            fragmentShader,
            blending: THREE.AdditiveBlending, //加法融合模式 glBlendFunc(GL_ONE, GL_ONE)
            depthTest: true,
            depthWrite: false,
            transparent: true

        } );
        
        
        return material
    }


    setSize(e){
        let viewport = e.viewport
        this.screenHeight = viewport.resolution.y
        this.setPerspective(this.fov, this.screenHeight)  
    }
    
    setFov(fov){
        this.fov = fov
        this.setPerspective(this.fov, this.screenHeight) 
    }
    
    
    setPerspective(fov, height){
        //this.uniforms.heightOfNearPlane.value = Math.abs(height / (2 * Math.tan(THREE.Math.degToRad(fov * 0.5))));
        let far = Math.abs(height / (2 * Math.tan(THREE.Math.degToRad(fov * 0.5))));
        this.material.uniforms.heightOfNearPlane.value = far 
    }

    
    
    update(delta){
        
        delta *= 1//更改速度
        
        this.material.uniforms.time.value = (this.material.uniforms.time.value + delta) % 1;
        
      
    }
}

export default FireParticle