WebGLRenderingContext.drawElements() - Web APIs 编辑

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

Syntax

void gl.drawElements(mode, count, type, offset);

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.

count

A GLsizei specifying the number of elements to be rendered.

type

A GLenum specifying the type of the values in the element array buffer. Possible values are:

• gl.UNSIGNED_BYTE
• gl.UNSIGNED_SHORT
• When using the OES_element_index_uint extension:
  • gl.UNSIGNED_INT

offset

A GLintptr specifying a byte offset in the element array buffer. Must be a valid multiple of the size of the given type.

Return value

None.

Exceptions

• If mode is not one of the accepted values, a gl.INVALID_ENUM error is thrown.
• If offset is not a valid multiple of the size of the given type, a gl.INVALID_OPERATION error is thrown.
• If count is negative, a gl.INVALID_VALUE error is thrown.

Examples

gl.drawElements(gl.POINTS, 8, gl.UNSIGNED_BYTE, 0);

Specifications

Browser compatibility

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See also

• WebGLRenderingContext.drawArrays()
• OES_element_index_uint
• WEBGL_multi_draw.multiDrawElementsWEBGL()