How To

Use Morph targets


Morph targets

Morph targets are a new feature introduced with Babylon.js v3.0.

Morph Target Before Morph Target After

Basics

Meshes can be deformed by using morph targets. A morph target must be built from a mesh with the EXACT same amount of vertices as the original mesh. Morph targets are used by the GPU to create the final geometry by applying the following formula:

final mesh = original mesh + sum((morph targets - original mesh) * morph targets influences)

For instance you can use morph targets to simulate the opening of a mouth. The initial mesh has a closed mouth. The morph target can be the same mesh but with an opened mouth. Then by changing the influence of the morph target (from 0 to 1) you can display either a closed or an opened mouth or a mix of both.

You can find live examples here: Playground Example Animated -


The following two examples are best seen in the full Playground where sliders can be used to change the influencers Playground Example With Standard Material -



Playground Example With PBR Material -

How to Use Morph Targets

To use morph targets, you first have to create a MorphTargetManager and affect it to a mesh:

var manager = new BABYLON.MorphTargetManager();
sphere.morphTargetManager = manager;

Then you can create MorphTarget either with the FromMesh static function:

var target = BABYLON.MorphTarget.FromMesh(sphereTarget, "target", 0.25);

or simply by creating a target and specifying positions and normals:

var target = new BABYLON.MorphTarget(name, influence);
target.setPositions(...);
target.setNormals(...);

Once done, you can specify the influence of a specific target with target.influence = 0.25

Targets with influence = 0 are disabled.

Here is a complete example with 4 targets:

var scramble = function(data) {
    for (index = 0; index < data.length; index ++) {
        data[index] += 0.1 * Math.random();
    }
}

// Main sphere
var sphere = BABYLON.Mesh.CreateSphere("sphere1", 16, 2, scene);

// Let's create some targets
var sphere2 = BABYLON.Mesh.CreateSphere("sphere2", 16, 2, scene);
sphere2.setEnabled(false);
sphere2.updateMeshPositions(scramble);

var sphere3 = BABYLON.Mesh.CreateSphere("sphere3", 16, 2, scene);
sphere3.setEnabled(false);

sphere3.scaling = new BABYLON.Vector3(2.1, 3.5, 1.0);
sphere3.bakeCurrentTransformIntoVertices();

var sphere4 = BABYLON.Mesh.CreateSphere("sphere4", 16, 2, scene);
sphere4.setEnabled(false);
sphere4.updateMeshPositions(scramble);

var sphere5 = BABYLON.Mesh.CreateSphere("sphere5", 16, 2, scene);
sphere5.setEnabled(false);

sphere5.scaling = new BABYLON.Vector3(1.0, 0.1, 1.0);
sphere5.bakeCurrentTransformIntoVertices();    

// Create a manager and affect it to the sphere
var manager = new BABYLON.MorphTargetManager();
sphere.morphTargetManager = manager;

// Add the targets
var target0 = BABYLON.MorphTarget.FromMesh(sphere2, "sphere2", 0.25);
manager.addTarget(target0);

var target1 = BABYLON.MorphTarget.FromMesh(sphere3, "sphere3", 0.25);
manager.addTarget(target1);

var target2 = BABYLON.MorphTarget.FromMesh(sphere4, "sphere4", 0.25);
manager.addTarget(target2);   

var target3 = BABYLON.MorphTarget.FromMesh(sphere5, "sphere5", 0.25);
manager.addTarget(target3);

At any time, you can remove a target with manager.removeTarget(target)

Limitations

  • Please be aware that most of the browsers are limited to 16 attributes per mesh. Adding a single morph target to a mesh add 2 new attributes (position + normal). This could quickly go beyond the max attributes limitation.
  • All targets within a same manager must have the same vertices count
  • A mesh and its MorphTargetManager must have the same vertices count