WebGLRenderingContext: drawArrays() method

{{APIRef("WebGL")}}{{AvailableInWorkers}}

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

Syntax

drawArrays(mode, first, count)

Parameters

• mode

  • : A {{domxref("WebGL_API/Types", "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 {{domxref("WebGL_API/Types", "GLint")}} specifying the starting index in the array of vector points.

• count

  • : A {{domxref("WebGL_API/Types", "GLsizei")}} specifying the number of indices to be rendered.

Return value

None ({{jsxref("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

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• {{domxref("WebGLRenderingContext.drawElements()")}}
• {{domxref("ANGLE_instanced_arrays.drawArraysInstancedANGLE()", "ext.drawArraysInstancedANGLE()")}}
• {{domxref("ANGLE_instanced_arrays.drawElementsInstancedANGLE()", "ext.drawElementsInstancedANGLE()")}}
• {{domxref("ANGLE_instanced_arrays.vertexAttribDivisorANGLE()", "ext.vertexAttribDivisorANGLE()")}}
• {{domxref("WebGL2RenderingContext.drawArraysInstanced()")}}
• {{domxref("WebGL2RenderingContext.drawElementsInstanced()")}}
• {{domxref("WebGL2RenderingContext.vertexAttribDivisor()")}}
• {{domxref("WEBGL_multi_draw.multiDrawArraysWEBGL()")}}