WebGLRenderingContext: drawArrays() method

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

The WebGLRenderingContext.drawArrays() method of the WebGL API renders primitives from array data.

Syntax

js
drawArrays(mode, first, count)

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.

Note: If mode is POINTS, gl_PointSize may need to be set for drawArrays to render, as its value is unknown if not explicitly written. Only some GPUs set its default as 1.0.

first

A GLint specifying the starting index in the array of vector points.

count

A GLsizei specifying the number of indices to be rendered.

Return value

None (undefined).

Exceptions

  • If mode is not one of the accepted values, a gl.INVALID_ENUM error is thrown.
  • If first or count are negative, a gl.INVALID_VALUE error is thrown.
  • if gl.CURRENT_PROGRAM is null, a gl.INVALID_OPERATION error is thrown.

Examples

js
gl.drawArrays(gl.POINTS, 0, 8);

Specifications

Specification
WebGL Specification
# 5.14.11

Browser compatibility

BCD tables only load in the browser

See also