BufferGeometry：如何渲染面组 [英] BufferGeometry: how to render groups of faces

问题描述

我有2个几何和2个网格。主要目标有时排除第一个几何体的一部分（因此我需要2个组）并在此时显示第二个几何体的一部分（总是1个组）。在发布r72之前我使用此代码

I have 2 geometries and 2 meshes. Main goal is sometimes exclude part of first geometry (so I need 2 groups for that) and show in this time part of 2nd geometry (always 1 group). Before release r72 I was use this code

第一几何：

bufCompaniesGeomNotActive.addDrawCall(0, geomCompaniesNotActive.faces.length * 3, 0);
bufCompaniesGeomNotActive.addDrawCall(0, 0, 0);

第二几何

bufCompaniesGeomActive.addDrawCall(0, 0, 0);

在r72版本中，addDrawCall刚刚重命名为addGroup。
但主要问题是第一几何中的2组。我之前尝试制作可见部分

In r72 release addDrawCall just renamed to addGroup. But main problem is 2 group's in 1st geometry. I was trying make visible part's like before

 floor.companiesGeomNotActive.groups[0].start = 0;
 floor.companiesGeomNotActive.groups[0].count = obj.startFaceIndexNotActive * 3;

 floor.companiesGeomNotActive.groups[1].start = obj.endFaceIndexNotActive * 3;
 floor.companiesGeomNotActive.groups[1].count = lengthNotActive - obj.endFaceIndexNotActive * 3;

但没有成功。
我发现方法 companiesGeomActive.setDrawRange（obj.startFaceIndexActive * 3,3 *（obj.endFaceIndexActive - obj.startFaceIndexActive））; 并且它有效但是如何我可以为多个组设置范围吗？

but no success. I've found method companiesGeomActive.setDrawRange(obj.startFaceIndexActive * 3, 3 * (obj.endFaceIndexActive - obj.startFaceIndexActive)); and it works but how can I set ranges for many groups?

推荐答案

BufferGeometry.groups 是现在用于支持 MultiMaterial （以前称为MeshFaceMaterial）。

BufferGeometry.groups is now used to support MultiMaterial ( formerly MeshFaceMaterial ).

geometry.clearGroups();
geometry.addGroup( start1, count1, 0 ); // materialIndex 0
geometry.addGroup( start2, count2, 1 ); // materialIndex 1

var material = new THREE.MultiMaterial( materialsArray );
var mesh = new THREE.Mesh( geometry, material );

如果你有一种材料并想要渲染面的子组，你可以使用一种模式像这样：

If you have a single material and want to render sub-groups of faces, you can use a pattern like so:

geometry.clearGroups();
geometry.addGroup( start1, count1, 0 ); // zero
geometry.addGroup( start2, count2, 0 ); // zero

var materialsArray = [ material ];
var material = new THREE.MultiMaterial( materialsArray );
var mesh = new THREE.Mesh( geometry, material );

geometry.drawRange 被忽略是 MultiMaterial 。

three.js r.72

three.js r.72

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