WebGLRenderingContext: drawArrays() method

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

Syntax

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

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

Specifications

• WebGL Specification

See also

• WebGLRenderingContext.drawElements()
• ext.drawArraysInstancedANGLE()
• ext.drawElementsInstancedANGLE()
• ext.vertexAttribDivisorANGLE()
• WebGL2RenderingContext.drawArraysInstanced()
• WebGL2RenderingContext.drawElementsInstanced()
• WebGL2RenderingContext.vertexAttribDivisor()
• WEBGL_multi_draw.multiDrawArraysWEBGL()