一個漸變環

通過shader控制漸變發範圍。

看起來像一個氣泡。

        const mat = {
            uniforms: {
                uColor: { value: new THREE.Color('#16585f') },
                uOp: { value: 1.0 }
            },
            vertexShader: `
            varying vec2 vUv;  
            void main(){     
                vUv = uv;         
                gl_Position	= projectionMatrix * modelViewMatrix * vec4(position, 1.0);
           }
             `,
            fragmentShader: `           
            varying vec2 vUv;
            uniform float uOp;
            uniform vec3 uColor;  
            float plot1(float a,float b,float x,float k){
                    float y = smoothstep(a,a+k