WEBGL_multi_draw: multiDrawArraysInstancedWEBGL() method

The WEBGL_multi_draw.multiDrawArraysInstancedWEBGL() method of the WebGL API renders multiple primitives from array data. It is identical to multiple calls to the gl.drawArraysInstanced() method.

Syntax

multiDrawArraysInstancedWEBGL(mode,
    firstsList, firstsOffset,
    countsList, countsOffset,
    instanceCountsList, instanceCountsOffset,
    drawCount)

Parameters

mode

A GLenum specifying the type primitive to render. Possible values are:

• gl.POINTS: Draws a single dot.
• gl.LINE_STRIP: Draws a straight line to the next vertex.
• gl.LINE_LOOP: Draws a straight line to the next vertex, and connects the last vertex back to the first.
• gl.LINES: Draws a line between a pair of vertices.
• gl.TRIANGLE_STRIP
• gl.TRIANGLE_FAN
• gl.TRIANGLES: Draws a triangle for a group of three vertices.

firstsList

An Int32Array or Array (of GLint) specifying a list of starting indices for the arrays of vector points.

firstsOffset

A GLuint defining the starting point into the firstsLists array.

countsList

An Int32Array or Array (of GLsizei) specifying a list of numbers of indices to be rendered.

countsOffset

A GLuint defining the starting point into the countsList array.

instanceCountsList

An Int32Array or Array (of GLsizei) specifying a list of numbers of instances of the range of elements to execute.

instanceCountsOffset

A GLuint defining the starting point into the instanceCountsList array.

drawCount

A GLsizei specifying the number of instances of the range of elements to execute.

Return value

None.

Exceptions

• If mode is not one of the accepted values, a gl.INVALID_ENUM error is thrown.
• If drawCount or items in firstsList, countsList, or instanceCountsList are negative, a gl.INVALID_VALUE error is thrown.
• if gl.CURRENT_PROGRAM is null, a gl.INVALID_OPERATION error is thrown.

Examples

const firsts = new Int32Array(/* … */);
const counts = new Int32Array(/* … */);
const instanceCounts = new Int32Array(/* … */);
ext.multiDrawArraysInstancedWEBGL(
  gl.TRIANGLES,
  firsts,
  0,
  counts,
  0,
  instanceCounts,
  0,
  firsts.length,
);

Specifications

Browser compatibility

See also

• WebGLRenderingContext.drawArrays()
• WebGL2RenderingContext.drawArraysInstanced()