向量点乘法概述
概要
使用three.js画两条线,挂点计算角度
绘制两条线段的letv1=newthree.vector3(0、0、0 ); let v2=new three.vector3(10,2,0 ); let v3=new three.vector3(0,10,0 ); let geometry1=new THREE.Geometry (; geometry1.vertices.push(V1,v2 ); let material1=new three.linebasicmaterial ({ color :0 x 0000 ff }; let line1=new three.line (geometry 1,material1); scene.add (行1; let geometry2=new THREE.Geometry (; geometry2.vertices.push(V1,v3 ); let material2=new three.linebasicmaterial ({ color : xff 0000 }; let line2=new three.line (geometry 2,material2); scene.add (线2; 效果:
2 .使用点乘法计算角度余弦值和角度。
//与三角形顶点p1相对应的夹角余弦值letdot=V2.clone(.normalize ) ).dot (v3.clone ).normalize () ) ) ) ) ) ) ) //结果为0console.log(math.ACOS(dot ) *180/Math.PI ); //结果为90