计算两个向量的法向量
function thirdAxisDirectVector(vector_1,vector_2){ var v1_x = vector_1.x; var v1_y = vector_1.y; var v1_z = vector_1.z; var v2_x = vector_2.x; var v2_y = vector_2.y; var v2_z = vector_2.z; var v3_x = v1_y*v2_z - v2_y*v1_z; var v3_y = v2_x*v1_z - v1_x*v2_z; var v3_z = v1_x*v2_y - v2_x*v1_y; var vector_3 = new THREE.Vector3(); vector_3.x = v3_x; vector_3.y = v3_y; vector_3.z = v3_z; return vector_3; }
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