VertexArray

new SuperMap3D.VertexArray(options具有以下属性的对象:) → VertexArray

创建顶点数组，该数组定义了构成顶点的属性，并包含一个可选的索引缓冲区，用于选择要渲染的顶点。 属性是使用对象文字定义的，如下例 1 所示。
Name Type Description
options具有以下属性的对象: Object
options.context Context The context in which the VertexArray gets created.
options.attributes Array.<Object> An array of attributes.
options.indexBuffer IndexBuffer optional An optional index buffer.
Returns:
The vertex array, ready for use with drawing.
Throws:
  • DeveloperError : Attribute must have a vertexBuffer.
  • DeveloperError : Attribute must have a componentsPerAttribute.
  • DeveloperError : Attribute must have a valid componentDatatype or not specify it.
  • DeveloperError : Attribute must have a strideInBytes less than or equal to 255 or not specify it.
  • DeveloperError : Index n is used by more than one attribute.
Examples:
// Example 1. Create a vertex array with vertices made up of three floating point
// values, e.g., a position, from a single vertex buffer.  No index buffer is used.
var positionBuffer = Buffer.createVertexBuffer({
    context : context,
    sizeInBytes : 12,
    usage : BufferUsage.STATIC_DRAW
});
var attributes = [
    {
        index                  : 0,
        enabled                : true,
        vertexBuffer           : positionBuffer,
        componentsPerAttribute : 3,
        componentDatatype      : ComponentDatatype.FLOAT,
        normalize              : false,
        offsetInBytes          : 0,
        strideInBytes          : 0 // tightly packed
        instanceDivisor        : 0 // not instanced
    }
];
var va = new VertexArray({
    context : context,
    attributes : attributes
});
// Example 2. Create a vertex array with vertices from two different vertex buffers.
// Each vertex has a three-component position and three-component normal.
var positionBuffer = Buffer.createVertexBuffer({
    context : context,
    sizeInBytes : 12,
    usage : BufferUsage.STATIC_DRAW
});
var normalBuffer = Buffer.createVertexBuffer({
    context : context,
    sizeInBytes : 12,
    usage : BufferUsage.STATIC_DRAW
});
var attributes = [
    {
        index                  : 0,
        vertexBuffer           : positionBuffer,
        componentsPerAttribute : 3,
        componentDatatype      : ComponentDatatype.FLOAT
    },
    {
        index                  : 1,
        vertexBuffer           : normalBuffer,
        componentsPerAttribute : 3,
        componentDatatype      : ComponentDatatype.FLOAT
    }
];
var va = new VertexArray({
    context : context,
    attributes : attributes
});
// Example 3. Creates the same vertex layout as Example 2 using a single
// vertex buffer, instead of two.
var buffer = Buffer.createVertexBuffer({
    context : context,
    sizeInBytes : 24,
    usage : BufferUsage.STATIC_DRAW
});
var attributes = [
    {
        vertexBuffer           : buffer,
        componentsPerAttribute : 3,
        componentDatatype      : ComponentDatatype.FLOAT,
        offsetInBytes          : 0,
        strideInBytes          : 24
    },
    {
        vertexBuffer           : buffer,
        componentsPerAttribute : 3,
        componentDatatype      : ComponentDatatype.FLOAT,
        normalize              : true,
        offsetInBytes          : 12,
        strideInBytes          : 24
    }
];
var va = new VertexArray({
    context : context,
    attributes : attributes
});
See:
  • Buffer#createVertexBuffer
  • Buffer#createIndexBuffer
  • Context#draw

Methods

staticSuperMap3D.VertexArray.fromGeometry(options)

从几何体创建一个顶点数组。几何体包含系统内存中的顶点属性和可选的索引数据，而顶点数组包含WebGL内存中的顶点缓冲区和可选的索引缓冲区，用于渲染。

geometry参数应该使用标准布局，如由BoxGeometry返回的几何体。

options 有以下四个属性:
  • geometry: 包含用于创建顶点阵列的数据的源几何体。
  • attributeLocations: 将几何属性名称映射到顶点着色器属性位置的对象。
  • bufferUsage: 顶点数组buffers的预期使用模式。在某些WebGL实现中，这可能会严重影响性能。参见BufferUsage。默认值:BufferUsage。DYNAMIC_DRAW
  • interleave: 确定所有属性是否在单个顶点buffer中交错，还是每个属性都存储在单独的顶点buffer中。默认值:false。

如果没有指定选项或者几何不包含数据，则返回的顶点数组为空。
Name Type Description
options Object 对象，定义用于创建顶点数组的几何形状、属性索引、缓冲区使用和顶点布局。
Throws:
Examples:
// Example 1. Creates a vertex array for rendering a box.  The default dynamic draw
// usage is used for the created vertex and index buffer.  The attributes are not
// interleaved by default.
var geometry = new BoxGeometry();
var va = VertexArray.fromGeometry({
    context            : context,
    geometry           : geometry,
    attributeLocations : GeometryPipeline.createAttributeLocations(geometry),
});
// Example 2. Creates a vertex array with interleaved attributes in a
// single vertex buffer.  The vertex and index buffer have static draw usage.
var va = VertexArray.fromGeometry({
    context            : context,
    geometry           : geometry,
    attributeLocations : GeometryPipeline.createAttributeLocations(geometry),
    bufferUsage        : BufferUsage.STATIC_DRAW,
    interleave         : true
});
// Example 3.  When the caller destroys the vertex array, it also destroys the
// attached vertex buffer(s) and index buffer.
va = va.destroy();
See:

getAttribute()

Index是属性数组中的位置，而不是属性的索引属性。