WebGLRenderingContext: drawElements() method
The WebGLRenderingContext.drawElements()
method of the WebGL API renders primitives from array data.
Syntax
js
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 of the bound element array buffer to be rendered. For example, to draw a wireframe triangle withgl.LINES
the count should be 2 endpoints per line × 3 lines = 6 elements. However to draw the same wireframe triangle withgl.LINE_STRIP
the element array buffer does not repeat the indices for the end of the first line/start of the second line, and end of the second line/start of the third line, socount
will be four. To draw the same triangle withgl.LINE_LOOP
the element array buffer does not repeat the first/last vertex either socount
will be three. 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 giventype
.
Return value
None (undefined
).
Exceptions
-
If
mode
is not one of the accepted values, agl.INVALID_ENUM
error is thrown. -
If
offset
is not a valid multiple of the size of the given type, agl.INVALID_OPERATION
error is thrown. - If
count
is negative, agl.INVALID_VALUE
error is thrown.
Examples
js
gl.drawElements(gl.POINTS, 8, gl.UNSIGNED_BYTE, 0);
Specifications
Specification |
---|
WebGL Specification # 5.14.11 |
Browser compatibility
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