• Displacement Map（置换贴图，也叫移位贴图）可以改变模型对象的几何形状，因此在提供最真实的效果的同时也会大幅增加渲染性能的开销。
• 只有一个r通道
• 在顶点着色器里面进行

#ifdef USE_DISPLACEMENTMAP
    uniform sampler2D displacementMap;
    uniform float displacementScale;
    uniform float displacementBias;
#endif

 #ifdef USE_DISPLACEMENTMAP
        transformed += normalize( objectNormal ) * ( texture2D( displacementMap, vUv ).x * displacementScale + displacementBias );
    #endif
vec4 mvPosition = vec4( transformed, 1.0 );

DisplacementMap 与 HeightMap 的区别

• Displacement mapping can mean (but doesn't always mean) a vector displacement at each point on the surface.
• Height mapping implies only a scalar displacement value, i.e. each point gets pushed along its normal.
• HeightMap是地形的输入数据